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Enci Wang, Jing Wang, Guinevere Kauffmann, Gyula I. G. Józsa, Cheng Li, H i scaling relations of galaxies in the environment of H i-rich and control galaxies observed by the Bluedisk project, Monthly Notices of the Royal Astronomical Society, Volume 449, Issue 2, 11 May 2015, Pages 2010–2023, https://doi.org/10.1093/mnras/stv390
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Abstract
Our work is based on the ‘Bluedisk’ project, a programme to map the neutral gas in a sample of 25 H i-rich spirals and a similar number of control galaxies with the Westerbork Synthesis Radio Telescope (WSRT). In this paper, we focus on the H i properties of the galaxies in the environment of our targeted galaxies. In total, we extract 65 galaxies from the WSRT cubes with stellar masses between 108 and 1011 M⊙. Most of these galaxies are located on the same H i mass–size relation and ‘H i-plane’ as normal spiral galaxies. We find that companions around H i-rich galaxies tend to be H i-rich as well and to have larger |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$|. This suggests a scenario of ‘H i conformity’, similar to the colour conformity found by Weinmann et al.: galaxies tend to adopt the H i properties of their neighbours. We visually inspect the outliers from the H i mass–size relation and galaxies which are offset from the H i plane and find that they show morphological and kinematical signatures of recent interactions with their environment. We speculate that these outliers have been disturbed by tidal or ram-pressure stripping processes, or in a few cases, by accretion events.
1 INTRODUCTION
In the recent years, a large number of surveys have obtained multiwavelength imaging and spectroscopy for large samples of galaxies at different redshifts. Thanks to these surveys, we have learned a lot about how galaxies form and evolve. However, many physical processes, such as the regulation of star formation by gas accretion, remain poorly understood.
The accretion of cold gas in the form of gas-rich dwarf galaxies can bring gas to galaxies and fuel star formation (Sancisi et al. 2008; Silk & Mamon 2012; Conselice et al. 2013). The presence of extraplanar gas (Chaves & Irwin 2001; Boomsma et al. 2005; Wakker et al. 2007), lopsided H i morphologies (Sancisi 1976; Shang et al. 1998; Thilker et al. 2007) and gas tails (Kregel & Sancisi 2001; Oosterloo et al. 2010) may directly be linked to ongoing cold gas accretion through mergers. While some portion of the gas in galaxies is being acquired through the accretion of dwarf galaxies, the inferred gas accretion rate is not sufficient to sustain star formation in galaxies (∼1.0 M⊙ yr−1) (Binney, Dehnen & Bertelli 2000). As a consequence, a large fraction of gas should be accreted directly from the intergalactic medium (IGM). Low-density galaxies lose their gas through tidal interactions or ram-pressure stripping, which may finally quench their star formation (Moore et al. 1996; Calcáneo-Roldán et al. 2000; Mayer et al. 2006; Kapferer et al. 2008; McCarthy et al. 2008; Chang, Macciò & Kang 2013). This process happens more frequently in dense environments.
The Bluedisk project, which was carried out with the Westerbork Synthesis Radio Telescope (WSRT), was designed to map the H i distribution is a sample of 25 unusually H i-rich galaxies. Galaxies with large H i excess usually have bluer and younger outer discs (Wang et al. 2011), and more metal-poor ionized gas (Moran et al. 2012). A sample of 25 control galaxies was also observed for comparison. These galaxies were closely matched in stellar mass, stellar surface mass density, redshift and inclination, but were not unusually rich in H i. The goal of the project was to determine whether there was any evidence for recent gas accretion on to unusually H i-rich galaxies by investigating and contrasting the H i structure and environment of the gas-rich galaxies with that of the control sample.
In the first paper of Bluedisk project, Wang et al. (2013, Paper I) concentrated on the H i size and morphology of the 42 targeted galaxies. They found that H i-rich galaxies do not differ from normal galaxies with respect to H i asymmetry indices or optical/H i disc position angle differences. This is inconsistent with a scenario in which the excess gas was brought in by mergers. In this paper, we extend this work to the galaxies in the neighbourhood of the targeted galaxies that lie within the WSRT data cubes.
Our paper is organized as follows. In Section 2, we briefly recap our observations, describe the data and the data processing that we carried out for our environmental study, including our procedure for accurate primary beam correction. In Section 3, we discuss our identification of galaxy neighbours via cross-matching with the spectroscopic catalogue of the Sloan Digital Sky Survey (SDSS) and how we build a uniform catalogue of these sources. In Section 4, we examine the H i mass–size relation and the correlation between H i and optical properties such as mass and stellar surface density for both the neighbours around H i-rich and control galaxies. In Section 5, we discuss the morphology and properties of galaxies which are found to be outliers from the standard scaling relations. We summarize our results in Section 6.
Throughout this paper, all the distance-dependent parameters are computed with Ω = 0.3, Λ = 0.7 and H0 = 70 km s−1 Mpc−1.
2 DATA
2.1 Observation and data reduction
The 50 targets were observed with the WSRT in 2011 and 2012. Target selection and data reduction are described in detail in Paper I. For detailed information on the targeted galaxies, we refer the reader to table 1 in Paper I.
The H i raw data cubes were reduced using a pipeline produced by Serra et al. (2012), based on the miriad reduction package (Sault, Teuben & Wright 1995). The data used in this paper are H i cubes built with a robust weighting of 0.4, which provides a suitable compromise between sensitivity and resolution. The pixel size is 4 arcsec and the velocity width for each channel is about 13 km s−1. The velocity resolution is 26 km s−1 (FWHM). The typical beam has half-power beamwidth of 16 × 16/sin(δ) arcsec2, where δ is the declination. Every cube has 148 channels, covers a redshift range of Δz = 0.006, and has a size of 1° on each side, which corresponds to a physical scale of 1.7 Mpc at a redshift z = 0.025. We point out that 92.0 per cent of the galaxies are within a systematic velocity difference of 500 km s−1 from the primary galaxies. However, some untargeted galaxies are not in the immediate neighbourhood of the primary galaxies: in the radial direction, the farthest galaxy is 884 km s−1 away. Hence, we are investigating a relatively large-scale environmental effect rather than the direct interaction between galaxy pairs in this paper.
We generate two-dimensional H i total-intensity maps (moment-0 maps) for each cube. First, we identify 3D regions of emission by a smoothing and clipping algorithm. We then add all the detected H i emission from all velocity channels. We also estimate errors for all non-zero pixels in the H i intensity map.
2.2 Physical properties of galaxies
The physical quantities required for this work are a spectrophotometric estimate of the stellar mass M*, stellar surface mass density μ* and the NUV−r colour. Stellar masses were taken from the MPA-JHU data base (http://www.mpa-garching.mpg.de/SDSS/DR7/), and are derived from SDSS photometry. The stellar surface mass density is defined as |$\mu _{*}=M_{*}\,(2\pi R_{\rm 50,z}^2)^{-1}$|, where R50, z is the physical radius which contains half the total light in the z band. The NUV magnitude is available from the Galaxy Evolution Explorer (GALEX) pipeline and the NUV−r colours are corrected for Galactic extinction. The H i size R1, |$R_{\rm 50,H\,\small {I}}$|, |$R_{\rm 90,H\,\small {I}}$| and rs, and H i mass |$M_{\rm H\,\small {I}}$|, are measured using our H i data cubes. R1 is the radius where radially averaged face-on H i column density reaches 1 M⊙ pc−2 (corresponding to 1.25 × 1020 atoms cm−2). |$R_{\rm 50,H\,\small {I}}$| and |$R_{\rm 90,H\,\small {I}}$| are the radii enclosing 50 and 90 per cent of the H i flux, respectively. Note that an inclination correction is not applied when calculating R1 for unresolved galaxies (|$R_{\rm 50,H\,\small {I}}$| less than 15 arcsec), because their H i sizes are less than the beam size. For these galaxies, the derived value of R1 should be regarded as an upper limit to the true value of R1. rs is the scalelength of the outer exponential disc, and is measured by assuming a point spread function (PSF)-convolved two-component model for the radial distribution of H i (see Wang et al. 2014 for details). The H i mass is defined as |$M_{{\rm H\,{\small {I}}}}$| = 2.356 × 105(Dlum Mpc−1)2(Ftot (Jy km s− 1)− 1), where Dlum is the luminosity distance and Ftot is the integrated H i-line flux density. The measurements of these parameters are described in more detail in Paper I.
2.3 Primary beam correction
Our work depends critically on the primary beam correction, which accounts for the attenuation by the primary beam towards large radii. We consider two methods. One is a non-parametric model (data cube) provided by Popping & Braun (2008), the other one is to apply a parametric correction function of the form cos 6(c × ν × d) as routinely used for the WSRT, where ν is the frequency in GHz and d is the angular distance from the pointing centres in degrees.
To test and calibrate both approaches, we compare the uncorrected flux densities of point sources in the radio continuum maps, which are an additional product of our data reduction pipeline (see Paper I) with the flux densities listed in the NRAO FIRST (Faint Images of the Radio Sky at Twenty-Centimeters; Becker, White & Helfand 1995) and NVSS (NRAO VLA Sky Survey; Condon et al. 1998) catalogues.
Specifically, we first extract sources from our continuum maps using Source Extractor. Then, we use the PSF-fitting method to derive the flux density of each source extracted from our continuum maps. With a detection threshold of 5σ, where σ is the rms noise with a typical value of 8.0 × 10−5 Jy beam−1, we extract more than two thousand sources from all images. This catalogue is then matched to the FIRST and NVSS catalogues. In total, there are 4128 sources in the FIRST catalogue (12Feb16 Version; Becker et al. 2012) located in these 50 H i observed regions, with integral flux density greater than 1 mJy. Among them, 1322 sources are classified as point sources at FIRST resolution (with a major axis FWHM of 2 arcsec). About one hundred detections in our cubes were matched with both FIRST and NVSS point sources. We restrict the analysis to point sources because FIRST and NVSS flux densities are very consistent with each other for point sources, with a scatter of 0.05 dex.
This way, we obtain a best fit c of 63, differing distinctly from the commonly used and recommended c = 68 (see WSRT web pages). This difference in c causes a 0.46 dex difference in flux intensity for pixels at the farthest edge of the continuum map (0| $_{.}^{\circ}$|71 from the map centre at redshift z = 0.025), and a largest difference of 0.17 dex for our farthest detected source. On average, the flux densities corrected with c = 63 are 0.04 dex smaller than that of c = 68 for our untargeted sources. Fig. 1 shows the comparison between the primary beam corrected PSF flux densities from our continuum maps and the FIRST/NVSS flux densities using both methods, the empirical analytic (standard) model, and Popping's non-parametric model. We can see a good linear correlation between the corrected PSF flux density and the FIRST/NVSS data. It is difficult to tell which model is better according to the data points, because the scatter is similar (∼0.7 dex). However, we remark that the standard recommended analytic model with c = 68 would have provided an insufficient primary beam correction in the wavelength range considered in this work. Since we confirm that the model of Popping & Braun (2008) works well, we adopt it for our primary beam correction for the Bluedisk data cubes.
3 SOURCE IDENTIFICATION
We use the source finder developed by Serra et al. (2012) to detect sources in the cubes. The pipeline uses a smooth-and-clip algorithm: it smooths the cube and searches for regions with a flux intensity above 3σ of the cube. The resulted catalogue of 1962 sources includes both real sources and noise peaks. We take a few steps to filter the real galaxies with reliable flux measurements. The first step is to match the H i catalogue with the SDSS spectroscopic catalogue. 163 H i sources are matched with optical galaxies, with an angular distance smaller than 20 arcsec (roughly the beam size). 10 of them have more than one matched optical counterpart. We further constrain in redshift by requiring |$|z_{\rm spec}-z_{\rm H\,\small {I}}|<0.001$|, which left us with 120 H i sources, and none of them have multiple optical counterparts. Although we may miss the galaxies with no optical spectroscopic observation, we efficiently exclude most of the unreliable sources from the H i catalogue.
In the following sections, we describe how we further select the sources with reliable H i flux measurements.
3.1 Defining the outermost H i contour
In Paper I, we describe how we build error maps for the H i moment-0 images. We use these error maps to determine an H i column density threshold that reliably defines an outermost contour for morphological analysis. The outermost contour should also contain most of the total flux of the source. The left-hand panel of Fig. 2 shows the signal-to-noise ratio (SNR) at different H i column density levels for all the detected sources. The black curve shows the median SNR, and the grey region shows the 20–80 per cent percentile range. The SNR is typically above 3 when the threshold is set to be 1020 atoms cm−2.
The middle panel of Fig. 2 shows how the fraction of the total flux of the galaxy varies as a function of column density limit. The back curve shows the median flux fraction for all sources, and the grey region shows the 20–80 per cent percentile range.1 We see that most of the galaxies retain more than 90 per cent of their total flux when the limiting contour level is 1020 atoms cm−2.
We require sources to contain at least 20 pixels in the moment-0 maps to be included in our catalogues. In the right-hand panel of Fig. 2, we show the fraction of sources that meet this criterion as a function of different density threshold cuts (the black curve). We also show how the curve changes if we change the resolving criteria to 10, 30 and 40 pixels. We can see more than 90 per cent of the sources are resolved with 20 pixels at a density detection threshold of 1020 atoms cm−2.
Based on the analysis shown above, we adopt 1020 atoms cm−2 as our H i column density threshold, because it is demonstrated to be a good threshold for reliably describing the shape and size of the H i while still retaining most of the H i mass, and it also includes most of the well-resolved H i sources.
3.2 Extracting sources with reliable H i fluxes
To estimate the reliability of our determinations of the total H i flux, we use a bootstrap method. We simulate a set of repeat observations by adding random noise with the same characteristics as the noise in the Bluedisk cubes, and measure the resulting variance if the total H i flux. In practice, we take the channels that have no detected sources from the data cube, and randomly repeat them to make noise cubes that have the same size as the Bluedisk data cubes. We add the noise cubes to the original Bluedisk cubes to make a ‘perturbed’ cube. We repeat this process 10 times for each original Bluedisk cube. In addition, we also generate error maps for these simulated cubes.
The left-hand panel of Fig. 3 shows how the scatter in the derived H i between the different perturbed cubes varies function of the original fluxes. The H i flux scatter rises sharply for H i fluxes less than 0.5 Jy km s−1, and becomes almost flat at a value of about 0.04 dex for H i fluxes greater than 0.5 Jy km s−1.
The right-hand panel of Fig. 3 shows the distribution of the ratios of simulated H i fluxes and input H i fluxes in two flux bins. The black histogram shows the ratio of the distribution for galaxies with H i fluxes greater than 0.5 Jy km s−1, and the red dot–dashed histogram shows the distribution for galaxies with H i fluxes less than 0.5 Jy km s−1. The simulated H i fluxes in the lower H i flux bin are clearly more scattered than in the higher H i flux bin. We further select galaxies that have an SNR of at least 3 for the 1020 atoms cm−2 H i column density contour. The distribution of their flux ratios is shown as the red histogram in Fig. 3. We find it to be similar to that of galaxies with high H i flux. In what follows, we exclude low H i flux sources (total H i fluxes less than 0.5 Jy km s−1) with an SNR of less than 3 in the 1020 atoms cm−2 contour. Our tests show that this ensures that the error in the H i fluxes we measured will be less than about 0.04 dex.
There are 43 targeted galaxies and 65 additional galaxies in the final sample. Among the galaxies that were not targeted, 45 galaxies are resolved and 20 galaxies are unresolved. Among these additional galaxies, 15 galaxies are located in the ‘peculiar cubes’ (Paper I), in which the targeted galaxy is not detected in H i or is otherwise disturbed. We exclude these galaxies in the analysis described below. We also divide our targeted galaxies into two parts according to whether they lie above or below the H i-plane defined in Catinella et al. (2010). Hereafter, targeted galaxies which lie above the H i-plane are referred to H i-rich galaxies (blue sample) and the cubes they reside in are referred as blue cubes. Similarly, the rest of targeted galaxies are referred as control sample and the rest of cubes are referred as control cubes. This definition is different to what was designed in observation, but it properly reflects the actual H i content of each system. At last, 23 blue-targeted galaxies (BTG), 20 control-targeted galaxies (CTG), 26 untargeted galaxies in blue cubes and 24 untargeted galaxies in control cubes are left.
The detailed properties of all the additional detected galaxies are listed in Table 1. Galaxies in ‘peculiar cubes’ are also listed in this table, but not used for analysis in the following part of the paper. As can be seen, they span stellar masses from 108 to 1011 M⊙ and H i masses from 108.5 to 1010.4 M⊙. Although our sample is small in size, it is unique in that it samples the environments rare, very H i-rich systems. Most of the galaxies are resolved in H i, enabling us to study their resolved morphology and their kinematics. Compared to the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies, our data are more sensitive.
ID . | RA . | Dec. . | z . | log M* . | μ* . | NUV−r . | |$\log M_{\rm H\,{}\small {I}}$| . | Dis . | R1 . | |$R_{\rm 50,H\,\small {I}}$| . | |$R_{\rm 90,H\,\small {I}}$| . | rs . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | . | . | (M⊙) . | (M⊙kpc− 2) . | . | (M⊙) . | (degree) . | (arcsec) . | (arcsec) . | (arcsec) . | (arcsec) . |
14 | 112.319 34 | 42.279 63 | 0.023 07 | 10.39 | 8.33 | 2.87 | 9.88 | 0.30 | 61 | 31 | 57 | 3.8 |
78 | 123.488 52 | 52.648 47 | 0.018 20 | 11.01 | 8.99 | 3.80 | 10.40 | 0.22 | 140 | 63 | 132 | 16.4 |
84 | 123.039 66 | 52.455 24 | 0.018 74 | 9.61 | 8.14 | 2.03 | 9.55 | 0.16 | 46 | 23 | 41 | – |
143 | 127.303 50 | 40.854 48 | 0.025 10 | 9.33 | 7.74 | 2.49 | 8.77 | 0.21 | 16 | 12 | 21 | 37.0 |
179 | 127.734 92 | 55.835 17 | 0.025 42 | 8.91 | 7.53 | 2.56 | 8.73 | 0.39 | 15 | 11 | 21 | 6.1 |
221 | 129.177 48 | 41.472 31 | 0.029 19 | 9.88 | 8.29 | 1.94 | 9.80 | 0.08 | 42 | 24 | 46 | 11.9 |
248 | 129.803 26 | 30.923 83 | 0.025 69 | 8.51 | 7.10 | 2.03 | 9.19 | 0.19 | 23 | 17 | 31 | 15.4 |
306 | 132.052 04 | 36.780 74 | 0.025 27 | 10.24 | 8.49 | 2.52 | 9.46 | 0.24 | 32 | 16 | 29 | 4.1 |
307 | 132.666 60 | 36.468 76 | 0.025 21 | 6.98 | 6.98 | 1.51 | 9.94 | 0.35 | 57 | 25 | 55 | – |
346 | 132.028 70 | 41.859 22 | 0.029 97 | 10.11 | 7.99 | 2.64 | 9.53 | 0.26 | 32 | 21 | 36 | – |
370 | 137.219 30 | 44.932 28 | 0.026 57 | 10.27 | 9.31 | 3.62 | 8.96 | 0.13 | 14 | 14 | 43 | 7.9 |
375 | 137.337 53 | 45.039 75 | 0.027 30 | 8.89 | 7.25 | 1.63 | 9.55 | 0.26 | 37 | 17 | 31 | 7.3 |
394 | 138.209 27 | 40.498 74 | 0.027 59 | 9.60 | 8.03 | 2.17 | 9.73 | 0.41 | 37 | 18 | 37 | 7.4 |
396 | 138.393 33 | 40.465 74 | 0.027 58 | 8.59 | 7.12 | 1.93 | 9.34 | 0.35 | 27 | 16 | 26 | 4.8 |
444 | 138.374 36 | 51.315 19 | 0.027 73 | 8.80 | 7.25 | – | 9.33 | 0.23 | 25 | 13 | 27 | 28.8 |
446 | 138.537 51 | 51.417 97 | 0.028 05 | 9.51 | 8.59 | – | 9.17 | 0.14 | 21 | 14 | 32 | 8.7 |
454 | 138.843 23 | 51.050 39 | 0.028 81 | 9.68 | 7.78 | 2.41 | 9.45 | 0.32 | 31 | 19 | 28 | 4.3 |
482 | 139.359 35 | 45.971 74 | 0.025 74 | 9.45 | 7.89 | 2.80 | 8.49 | 0.20 | 6 | 14 | 28 | 22.2 |
483 | 139.559 19 | 45.651 71 | 0.026 90 | 10.70 | 8.47 | 2.87 | 10.16 | 0.30 | 68 | 35 | 61 | 5.0 |
517 | 139.904 99 | 32.353 20 | 0.026 52 | 9.72 | 8.54 | 2.01 | 9.25 | 0.23 | 24 | 18 | 45 | 11.3 |
563 | 141.202 93 | 49.398 27 | 0.027 23 | 9.73 | 8.27 | 3.30 | 8.72 | 0.24 | 15 | 10 | 19 | – |
773 | 153.034 46 | 46.293 71 | 0.024 25 | 10.34 | 8.48 | 2.63 | 10.03 | 0.40 | 47 | 34 | 66 | – |
776 | 152.849 76 | 45.735 39 | 0.023 75 | 8.69 | 7.20 | 1.60 | 8.88 | 0.23 | 19 | 12 | 21 | – |
840 | 153.807 16 | 56.603 31 | 0.026 67 | 8.82 | 7.43 | 1.24 | 9.41 | 0.07 | 28 | 17 | 33 | 8.9 |
889 | 154.253 28 | 55.880 05 | 0.024 37 | 9.77 | 8.28 | 2.34 | 9.56 | 0.28 | 36 | 18 | 33 | 6.7 |
941 | 153.811 51 | 58.691 74 | 0.022 95 | 8.61 | 7.73 | 1.80 | 9.12 | 0.29 | 6 | 29 | 49 | 4.5 |
983 | 162.506 34 | 36.256 77 | 0.021 90 | 9.75 | 8.09 | 3.12 | 8.47 | 0.09 | 6 | 17 | 27 | – |
997 | 162.754 26 | 36.192 58 | 0.023 80 | 9.85 | 7.80 | 2.23 | 9.98 | 0.23 | 55 | 23 | 47 | – |
999 | 162.494 49 | 36.414 99 | 0.023 27 | 9.50 | 8.20 | 3.34 | 8.78 | 0.08 | 17 | 13 | 24 | 5.7 |
1020 | 166.868 89 | 35.463 65 | 0.028 28 | – | – | 3.05 | 9.87 | 0.10 | 37 | 26 | 58 | – |
1022 | 166.959 02 | 35.402 99 | 0.028 40 | 10.47 | 8.81 | 3.49 | 9.56 | 0.07 | 36 | 18 | 32 | 18.0 |
1024 | 166.958 21 | 35.684 83 | 0.028 46 | 10.30 | 9.10 | 2.97 | 9.62 | 0.22 | 41 | 25 | 42 | 9.1 |
1027 | 167.105 16 | 35.330 68 | 0.028 88 | 8.96 | 7.33 | 3.81 | 8.94 | 0.16 | 18 | 13 | 25 | – |
1042 | 168.529 72 | 34.308 86 | 0.025 26 | 8.70 | 6.97 | 1.91 | 9.09 | 0.16 | 25 | 18 | 31 | 17.1 |
1104 | 177.575 56 | 35.254 09 | 0.021 28 | 10.22 | 8.97 | 2.84 | 10.08 | 0.36 | 68 | 35 | 76 | – |
1143 | 185.610 22 | 40.761 68 | 0.022 92 | 8.40 | 7.68 | −0.14 | 9.14 | 0.17 | 28 | 16 | 27 | 16.9 |
1183 | 193.237 60 | 51.826 84 | 0.027 62 | 8.58 | 7.78 | 1.50 | 8.90 | 0.20 | 16 | 11 | 22 | 23.2 |
1230 | 196.763 12 | 57.865 14 | 0.028 74 | 8.77 | 7.04 | 2.04 | 9.09 | 0.27 | 19 | 12 | 22 | 4.6 |
1254 | 198.423 30 | 47.299 23 | 0.028 08 | 8.80 | 7.20 | 1.22 | 9.19 | 0.20 | 23 | 15 | 25 | 6.3 |
1259 | 198.260 18 | 47.345 18 | 0.028 41 | 8.76 | 7.28 | 1.79 | 9.02 | 0.11 | 17 | 14 | 30 | 10.4 |
1261 | 197.860 26 | 47.440 52 | 0.028 61 | 9.03 | 7.29 | 2.46 | 8.92 | 0.25 | 15 | 9 | 15 | – |
1296 | 198.845 72 | 35.173 51 | 0.023 09 | 8.90 | 8.12 | 1.82 | 8.98 | 0.19 | 19 | 12 | 22 | 7.1 |
1298 | 198.670 04 | 35.036 38 | 0.023 74 | 8.67 | 7.46 | 1.61 | 9.21 | 0.28 | 22 | 14 | 29 | 13.2 |
1323 | 203.28 55 | 40.853 07 | 0.024 00 | 8.88 | 7.70 | 1.24 | 8.97 | 0.33 | 10 | 22 | 33 | 3.7 |
1407 | 212.509 86 | 38.708 12 | 0.025 76 | 9.86 | 8.31 | 3.81 | 9.67 | 0.21 | 34 | 28 | 52 | – |
1410 | 212.677 58 | 38.718 42 | 0.025 61 | 8.57 | 7.42 | 1.30 | 9.26 | 0.18 | 23 | 19 | 47 | – |
1411 | 212.627 10 | 38.739 50 | 0.026 06 | 8.95 | 7.86 | 1.23 | 9.44 | 0.15 | 29 | 16 | 31 | 12.5 |
1414 | 212.695 82 | 38.759 70 | 0.025 70 | 8.74 | 7.46 | 1.72 | 8.81 | 0.14 | 15 | 11 | 25 | – |
1415 | 212.729 23 | 38.785 92 | 0.025 80 | 8.43 | 7.14 | 1.54 | 9.13 | 0.13 | 14 | 15 | 31 | 7.2 |
1533 | 241.434 11 | 36.275 08 | 0.031 23 | 9.40 | 7.50 | 1.74 | 9.79 | 0.30 | 44 | 23 | 38 | – |
1554 | 242.242 89 | 36.610 88 | 0.030 14 | 11.02 | 8.83 | 3.33 | 10.42 | 0.31 | 26 | 50 | 104 | 26.6 |
1605 | 246.164 76 | 41.019 95 | 0.027 12 | 8.79 | 7.33 | 0.66 | 9.70 | 0.10 | 33 | 15 | 31 | 6.1 |
1632 | 246.062 71 | 41.110 62 | 0.029 26 | 9.97 | 8.21 | 3.27 | 9.70 | 0.22 | 38 | 17 | 33 | 9.6 |
1639 | 246.708 60 | 40.917 86 | 0.029 15 | 8.93 | 7.68 | 1.83 | 9.21 | 0.34 | 21 | 29 | 33 | 9.0 |
1643 | 246.130 86 | 40.684 45 | 0.029 43 | 8.80 | 7.49 | 1.10 | 9.06 | 0.28 | 20 | 18 | 36 | – |
1647 | 246.084 27 | 40.865 01 | 0.030 00 | 9.34 | 7.50 | 2.46 | 9.13 | 0.16 | 17 | 12 | 44 | – |
1648 | 245.998 46 | 41.138 17 | 0.030 29 | 9.08 | 7.39 | 1.34 | 9.59 | 0.27 | 34 | 17 | 33 | 20.6 |
1663 | 250.622 96 | 42.262 85 | 0.027 50 | 8.78 | 7.27 | 1.27 | 9.08 | 0.14 | 20 | 16 | 32 | 15.6 |
1669 | 250.562 63 | 42.059 96 | 0.027 80 | 8.82 | 7.68 | 1.96 | 9.17 | 0.22 | 20 | 18 | 50 | 19.7 |
1700 | 251.488 97 | 39.985 83 | 0.030 20 | 10.17 | 8.22 | 3.18 | 9.69 | 0.36 | 5 | 20 | 35 | 7.2 |
1713 | 251.873 96 | 40.565 70 | 0.031 08 | 8.92 | 7.44 | 1.39 | 9.68 | 0.32 | 37 | 19 | 32 | – |
1725 | 258.806 17 | 30.451 46 | 0.028 64 | 9.98 | 8.17 | 2.56 | 9.66 | 0.31 | 39 | 20 | 34 | – |
1774 | 259.682 21 | 58.135 13 | 0.029 08 | 10.95 | 8.85 | 3.60 | 9.98 | 0.39 | 55 | 26 | 48 | 13.5 |
1795 | 258.779 94 | 58.240 45 | 0.031 01 | 10.20 | 8.35 | 3.08 | 9.78 | 0.26 | 40 | 18 | 38 | – |
1907 | 262.173 43 | 57.114 76 | 0.028 12 | – | – | −0.42 | 9.03 | 0.03 | 17 | 11 | 23 | 16.7 |
ID . | RA . | Dec. . | z . | log M* . | μ* . | NUV−r . | |$\log M_{\rm H\,{}\small {I}}$| . | Dis . | R1 . | |$R_{\rm 50,H\,\small {I}}$| . | |$R_{\rm 90,H\,\small {I}}$| . | rs . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | . | . | (M⊙) . | (M⊙kpc− 2) . | . | (M⊙) . | (degree) . | (arcsec) . | (arcsec) . | (arcsec) . | (arcsec) . |
14 | 112.319 34 | 42.279 63 | 0.023 07 | 10.39 | 8.33 | 2.87 | 9.88 | 0.30 | 61 | 31 | 57 | 3.8 |
78 | 123.488 52 | 52.648 47 | 0.018 20 | 11.01 | 8.99 | 3.80 | 10.40 | 0.22 | 140 | 63 | 132 | 16.4 |
84 | 123.039 66 | 52.455 24 | 0.018 74 | 9.61 | 8.14 | 2.03 | 9.55 | 0.16 | 46 | 23 | 41 | – |
143 | 127.303 50 | 40.854 48 | 0.025 10 | 9.33 | 7.74 | 2.49 | 8.77 | 0.21 | 16 | 12 | 21 | 37.0 |
179 | 127.734 92 | 55.835 17 | 0.025 42 | 8.91 | 7.53 | 2.56 | 8.73 | 0.39 | 15 | 11 | 21 | 6.1 |
221 | 129.177 48 | 41.472 31 | 0.029 19 | 9.88 | 8.29 | 1.94 | 9.80 | 0.08 | 42 | 24 | 46 | 11.9 |
248 | 129.803 26 | 30.923 83 | 0.025 69 | 8.51 | 7.10 | 2.03 | 9.19 | 0.19 | 23 | 17 | 31 | 15.4 |
306 | 132.052 04 | 36.780 74 | 0.025 27 | 10.24 | 8.49 | 2.52 | 9.46 | 0.24 | 32 | 16 | 29 | 4.1 |
307 | 132.666 60 | 36.468 76 | 0.025 21 | 6.98 | 6.98 | 1.51 | 9.94 | 0.35 | 57 | 25 | 55 | – |
346 | 132.028 70 | 41.859 22 | 0.029 97 | 10.11 | 7.99 | 2.64 | 9.53 | 0.26 | 32 | 21 | 36 | – |
370 | 137.219 30 | 44.932 28 | 0.026 57 | 10.27 | 9.31 | 3.62 | 8.96 | 0.13 | 14 | 14 | 43 | 7.9 |
375 | 137.337 53 | 45.039 75 | 0.027 30 | 8.89 | 7.25 | 1.63 | 9.55 | 0.26 | 37 | 17 | 31 | 7.3 |
394 | 138.209 27 | 40.498 74 | 0.027 59 | 9.60 | 8.03 | 2.17 | 9.73 | 0.41 | 37 | 18 | 37 | 7.4 |
396 | 138.393 33 | 40.465 74 | 0.027 58 | 8.59 | 7.12 | 1.93 | 9.34 | 0.35 | 27 | 16 | 26 | 4.8 |
444 | 138.374 36 | 51.315 19 | 0.027 73 | 8.80 | 7.25 | – | 9.33 | 0.23 | 25 | 13 | 27 | 28.8 |
446 | 138.537 51 | 51.417 97 | 0.028 05 | 9.51 | 8.59 | – | 9.17 | 0.14 | 21 | 14 | 32 | 8.7 |
454 | 138.843 23 | 51.050 39 | 0.028 81 | 9.68 | 7.78 | 2.41 | 9.45 | 0.32 | 31 | 19 | 28 | 4.3 |
482 | 139.359 35 | 45.971 74 | 0.025 74 | 9.45 | 7.89 | 2.80 | 8.49 | 0.20 | 6 | 14 | 28 | 22.2 |
483 | 139.559 19 | 45.651 71 | 0.026 90 | 10.70 | 8.47 | 2.87 | 10.16 | 0.30 | 68 | 35 | 61 | 5.0 |
517 | 139.904 99 | 32.353 20 | 0.026 52 | 9.72 | 8.54 | 2.01 | 9.25 | 0.23 | 24 | 18 | 45 | 11.3 |
563 | 141.202 93 | 49.398 27 | 0.027 23 | 9.73 | 8.27 | 3.30 | 8.72 | 0.24 | 15 | 10 | 19 | – |
773 | 153.034 46 | 46.293 71 | 0.024 25 | 10.34 | 8.48 | 2.63 | 10.03 | 0.40 | 47 | 34 | 66 | – |
776 | 152.849 76 | 45.735 39 | 0.023 75 | 8.69 | 7.20 | 1.60 | 8.88 | 0.23 | 19 | 12 | 21 | – |
840 | 153.807 16 | 56.603 31 | 0.026 67 | 8.82 | 7.43 | 1.24 | 9.41 | 0.07 | 28 | 17 | 33 | 8.9 |
889 | 154.253 28 | 55.880 05 | 0.024 37 | 9.77 | 8.28 | 2.34 | 9.56 | 0.28 | 36 | 18 | 33 | 6.7 |
941 | 153.811 51 | 58.691 74 | 0.022 95 | 8.61 | 7.73 | 1.80 | 9.12 | 0.29 | 6 | 29 | 49 | 4.5 |
983 | 162.506 34 | 36.256 77 | 0.021 90 | 9.75 | 8.09 | 3.12 | 8.47 | 0.09 | 6 | 17 | 27 | – |
997 | 162.754 26 | 36.192 58 | 0.023 80 | 9.85 | 7.80 | 2.23 | 9.98 | 0.23 | 55 | 23 | 47 | – |
999 | 162.494 49 | 36.414 99 | 0.023 27 | 9.50 | 8.20 | 3.34 | 8.78 | 0.08 | 17 | 13 | 24 | 5.7 |
1020 | 166.868 89 | 35.463 65 | 0.028 28 | – | – | 3.05 | 9.87 | 0.10 | 37 | 26 | 58 | – |
1022 | 166.959 02 | 35.402 99 | 0.028 40 | 10.47 | 8.81 | 3.49 | 9.56 | 0.07 | 36 | 18 | 32 | 18.0 |
1024 | 166.958 21 | 35.684 83 | 0.028 46 | 10.30 | 9.10 | 2.97 | 9.62 | 0.22 | 41 | 25 | 42 | 9.1 |
1027 | 167.105 16 | 35.330 68 | 0.028 88 | 8.96 | 7.33 | 3.81 | 8.94 | 0.16 | 18 | 13 | 25 | – |
1042 | 168.529 72 | 34.308 86 | 0.025 26 | 8.70 | 6.97 | 1.91 | 9.09 | 0.16 | 25 | 18 | 31 | 17.1 |
1104 | 177.575 56 | 35.254 09 | 0.021 28 | 10.22 | 8.97 | 2.84 | 10.08 | 0.36 | 68 | 35 | 76 | – |
1143 | 185.610 22 | 40.761 68 | 0.022 92 | 8.40 | 7.68 | −0.14 | 9.14 | 0.17 | 28 | 16 | 27 | 16.9 |
1183 | 193.237 60 | 51.826 84 | 0.027 62 | 8.58 | 7.78 | 1.50 | 8.90 | 0.20 | 16 | 11 | 22 | 23.2 |
1230 | 196.763 12 | 57.865 14 | 0.028 74 | 8.77 | 7.04 | 2.04 | 9.09 | 0.27 | 19 | 12 | 22 | 4.6 |
1254 | 198.423 30 | 47.299 23 | 0.028 08 | 8.80 | 7.20 | 1.22 | 9.19 | 0.20 | 23 | 15 | 25 | 6.3 |
1259 | 198.260 18 | 47.345 18 | 0.028 41 | 8.76 | 7.28 | 1.79 | 9.02 | 0.11 | 17 | 14 | 30 | 10.4 |
1261 | 197.860 26 | 47.440 52 | 0.028 61 | 9.03 | 7.29 | 2.46 | 8.92 | 0.25 | 15 | 9 | 15 | – |
1296 | 198.845 72 | 35.173 51 | 0.023 09 | 8.90 | 8.12 | 1.82 | 8.98 | 0.19 | 19 | 12 | 22 | 7.1 |
1298 | 198.670 04 | 35.036 38 | 0.023 74 | 8.67 | 7.46 | 1.61 | 9.21 | 0.28 | 22 | 14 | 29 | 13.2 |
1323 | 203.28 55 | 40.853 07 | 0.024 00 | 8.88 | 7.70 | 1.24 | 8.97 | 0.33 | 10 | 22 | 33 | 3.7 |
1407 | 212.509 86 | 38.708 12 | 0.025 76 | 9.86 | 8.31 | 3.81 | 9.67 | 0.21 | 34 | 28 | 52 | – |
1410 | 212.677 58 | 38.718 42 | 0.025 61 | 8.57 | 7.42 | 1.30 | 9.26 | 0.18 | 23 | 19 | 47 | – |
1411 | 212.627 10 | 38.739 50 | 0.026 06 | 8.95 | 7.86 | 1.23 | 9.44 | 0.15 | 29 | 16 | 31 | 12.5 |
1414 | 212.695 82 | 38.759 70 | 0.025 70 | 8.74 | 7.46 | 1.72 | 8.81 | 0.14 | 15 | 11 | 25 | – |
1415 | 212.729 23 | 38.785 92 | 0.025 80 | 8.43 | 7.14 | 1.54 | 9.13 | 0.13 | 14 | 15 | 31 | 7.2 |
1533 | 241.434 11 | 36.275 08 | 0.031 23 | 9.40 | 7.50 | 1.74 | 9.79 | 0.30 | 44 | 23 | 38 | – |
1554 | 242.242 89 | 36.610 88 | 0.030 14 | 11.02 | 8.83 | 3.33 | 10.42 | 0.31 | 26 | 50 | 104 | 26.6 |
1605 | 246.164 76 | 41.019 95 | 0.027 12 | 8.79 | 7.33 | 0.66 | 9.70 | 0.10 | 33 | 15 | 31 | 6.1 |
1632 | 246.062 71 | 41.110 62 | 0.029 26 | 9.97 | 8.21 | 3.27 | 9.70 | 0.22 | 38 | 17 | 33 | 9.6 |
1639 | 246.708 60 | 40.917 86 | 0.029 15 | 8.93 | 7.68 | 1.83 | 9.21 | 0.34 | 21 | 29 | 33 | 9.0 |
1643 | 246.130 86 | 40.684 45 | 0.029 43 | 8.80 | 7.49 | 1.10 | 9.06 | 0.28 | 20 | 18 | 36 | – |
1647 | 246.084 27 | 40.865 01 | 0.030 00 | 9.34 | 7.50 | 2.46 | 9.13 | 0.16 | 17 | 12 | 44 | – |
1648 | 245.998 46 | 41.138 17 | 0.030 29 | 9.08 | 7.39 | 1.34 | 9.59 | 0.27 | 34 | 17 | 33 | 20.6 |
1663 | 250.622 96 | 42.262 85 | 0.027 50 | 8.78 | 7.27 | 1.27 | 9.08 | 0.14 | 20 | 16 | 32 | 15.6 |
1669 | 250.562 63 | 42.059 96 | 0.027 80 | 8.82 | 7.68 | 1.96 | 9.17 | 0.22 | 20 | 18 | 50 | 19.7 |
1700 | 251.488 97 | 39.985 83 | 0.030 20 | 10.17 | 8.22 | 3.18 | 9.69 | 0.36 | 5 | 20 | 35 | 7.2 |
1713 | 251.873 96 | 40.565 70 | 0.031 08 | 8.92 | 7.44 | 1.39 | 9.68 | 0.32 | 37 | 19 | 32 | – |
1725 | 258.806 17 | 30.451 46 | 0.028 64 | 9.98 | 8.17 | 2.56 | 9.66 | 0.31 | 39 | 20 | 34 | – |
1774 | 259.682 21 | 58.135 13 | 0.029 08 | 10.95 | 8.85 | 3.60 | 9.98 | 0.39 | 55 | 26 | 48 | 13.5 |
1795 | 258.779 94 | 58.240 45 | 0.031 01 | 10.20 | 8.35 | 3.08 | 9.78 | 0.26 | 40 | 18 | 38 | – |
1907 | 262.173 43 | 57.114 76 | 0.028 12 | – | – | −0.42 | 9.03 | 0.03 | 17 | 11 | 23 | 16.7 |
ID . | RA . | Dec. . | z . | log M* . | μ* . | NUV−r . | |$\log M_{\rm H\,{}\small {I}}$| . | Dis . | R1 . | |$R_{\rm 50,H\,\small {I}}$| . | |$R_{\rm 90,H\,\small {I}}$| . | rs . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | . | . | (M⊙) . | (M⊙kpc− 2) . | . | (M⊙) . | (degree) . | (arcsec) . | (arcsec) . | (arcsec) . | (arcsec) . |
14 | 112.319 34 | 42.279 63 | 0.023 07 | 10.39 | 8.33 | 2.87 | 9.88 | 0.30 | 61 | 31 | 57 | 3.8 |
78 | 123.488 52 | 52.648 47 | 0.018 20 | 11.01 | 8.99 | 3.80 | 10.40 | 0.22 | 140 | 63 | 132 | 16.4 |
84 | 123.039 66 | 52.455 24 | 0.018 74 | 9.61 | 8.14 | 2.03 | 9.55 | 0.16 | 46 | 23 | 41 | – |
143 | 127.303 50 | 40.854 48 | 0.025 10 | 9.33 | 7.74 | 2.49 | 8.77 | 0.21 | 16 | 12 | 21 | 37.0 |
179 | 127.734 92 | 55.835 17 | 0.025 42 | 8.91 | 7.53 | 2.56 | 8.73 | 0.39 | 15 | 11 | 21 | 6.1 |
221 | 129.177 48 | 41.472 31 | 0.029 19 | 9.88 | 8.29 | 1.94 | 9.80 | 0.08 | 42 | 24 | 46 | 11.9 |
248 | 129.803 26 | 30.923 83 | 0.025 69 | 8.51 | 7.10 | 2.03 | 9.19 | 0.19 | 23 | 17 | 31 | 15.4 |
306 | 132.052 04 | 36.780 74 | 0.025 27 | 10.24 | 8.49 | 2.52 | 9.46 | 0.24 | 32 | 16 | 29 | 4.1 |
307 | 132.666 60 | 36.468 76 | 0.025 21 | 6.98 | 6.98 | 1.51 | 9.94 | 0.35 | 57 | 25 | 55 | – |
346 | 132.028 70 | 41.859 22 | 0.029 97 | 10.11 | 7.99 | 2.64 | 9.53 | 0.26 | 32 | 21 | 36 | – |
370 | 137.219 30 | 44.932 28 | 0.026 57 | 10.27 | 9.31 | 3.62 | 8.96 | 0.13 | 14 | 14 | 43 | 7.9 |
375 | 137.337 53 | 45.039 75 | 0.027 30 | 8.89 | 7.25 | 1.63 | 9.55 | 0.26 | 37 | 17 | 31 | 7.3 |
394 | 138.209 27 | 40.498 74 | 0.027 59 | 9.60 | 8.03 | 2.17 | 9.73 | 0.41 | 37 | 18 | 37 | 7.4 |
396 | 138.393 33 | 40.465 74 | 0.027 58 | 8.59 | 7.12 | 1.93 | 9.34 | 0.35 | 27 | 16 | 26 | 4.8 |
444 | 138.374 36 | 51.315 19 | 0.027 73 | 8.80 | 7.25 | – | 9.33 | 0.23 | 25 | 13 | 27 | 28.8 |
446 | 138.537 51 | 51.417 97 | 0.028 05 | 9.51 | 8.59 | – | 9.17 | 0.14 | 21 | 14 | 32 | 8.7 |
454 | 138.843 23 | 51.050 39 | 0.028 81 | 9.68 | 7.78 | 2.41 | 9.45 | 0.32 | 31 | 19 | 28 | 4.3 |
482 | 139.359 35 | 45.971 74 | 0.025 74 | 9.45 | 7.89 | 2.80 | 8.49 | 0.20 | 6 | 14 | 28 | 22.2 |
483 | 139.559 19 | 45.651 71 | 0.026 90 | 10.70 | 8.47 | 2.87 | 10.16 | 0.30 | 68 | 35 | 61 | 5.0 |
517 | 139.904 99 | 32.353 20 | 0.026 52 | 9.72 | 8.54 | 2.01 | 9.25 | 0.23 | 24 | 18 | 45 | 11.3 |
563 | 141.202 93 | 49.398 27 | 0.027 23 | 9.73 | 8.27 | 3.30 | 8.72 | 0.24 | 15 | 10 | 19 | – |
773 | 153.034 46 | 46.293 71 | 0.024 25 | 10.34 | 8.48 | 2.63 | 10.03 | 0.40 | 47 | 34 | 66 | – |
776 | 152.849 76 | 45.735 39 | 0.023 75 | 8.69 | 7.20 | 1.60 | 8.88 | 0.23 | 19 | 12 | 21 | – |
840 | 153.807 16 | 56.603 31 | 0.026 67 | 8.82 | 7.43 | 1.24 | 9.41 | 0.07 | 28 | 17 | 33 | 8.9 |
889 | 154.253 28 | 55.880 05 | 0.024 37 | 9.77 | 8.28 | 2.34 | 9.56 | 0.28 | 36 | 18 | 33 | 6.7 |
941 | 153.811 51 | 58.691 74 | 0.022 95 | 8.61 | 7.73 | 1.80 | 9.12 | 0.29 | 6 | 29 | 49 | 4.5 |
983 | 162.506 34 | 36.256 77 | 0.021 90 | 9.75 | 8.09 | 3.12 | 8.47 | 0.09 | 6 | 17 | 27 | – |
997 | 162.754 26 | 36.192 58 | 0.023 80 | 9.85 | 7.80 | 2.23 | 9.98 | 0.23 | 55 | 23 | 47 | – |
999 | 162.494 49 | 36.414 99 | 0.023 27 | 9.50 | 8.20 | 3.34 | 8.78 | 0.08 | 17 | 13 | 24 | 5.7 |
1020 | 166.868 89 | 35.463 65 | 0.028 28 | – | – | 3.05 | 9.87 | 0.10 | 37 | 26 | 58 | – |
1022 | 166.959 02 | 35.402 99 | 0.028 40 | 10.47 | 8.81 | 3.49 | 9.56 | 0.07 | 36 | 18 | 32 | 18.0 |
1024 | 166.958 21 | 35.684 83 | 0.028 46 | 10.30 | 9.10 | 2.97 | 9.62 | 0.22 | 41 | 25 | 42 | 9.1 |
1027 | 167.105 16 | 35.330 68 | 0.028 88 | 8.96 | 7.33 | 3.81 | 8.94 | 0.16 | 18 | 13 | 25 | – |
1042 | 168.529 72 | 34.308 86 | 0.025 26 | 8.70 | 6.97 | 1.91 | 9.09 | 0.16 | 25 | 18 | 31 | 17.1 |
1104 | 177.575 56 | 35.254 09 | 0.021 28 | 10.22 | 8.97 | 2.84 | 10.08 | 0.36 | 68 | 35 | 76 | – |
1143 | 185.610 22 | 40.761 68 | 0.022 92 | 8.40 | 7.68 | −0.14 | 9.14 | 0.17 | 28 | 16 | 27 | 16.9 |
1183 | 193.237 60 | 51.826 84 | 0.027 62 | 8.58 | 7.78 | 1.50 | 8.90 | 0.20 | 16 | 11 | 22 | 23.2 |
1230 | 196.763 12 | 57.865 14 | 0.028 74 | 8.77 | 7.04 | 2.04 | 9.09 | 0.27 | 19 | 12 | 22 | 4.6 |
1254 | 198.423 30 | 47.299 23 | 0.028 08 | 8.80 | 7.20 | 1.22 | 9.19 | 0.20 | 23 | 15 | 25 | 6.3 |
1259 | 198.260 18 | 47.345 18 | 0.028 41 | 8.76 | 7.28 | 1.79 | 9.02 | 0.11 | 17 | 14 | 30 | 10.4 |
1261 | 197.860 26 | 47.440 52 | 0.028 61 | 9.03 | 7.29 | 2.46 | 8.92 | 0.25 | 15 | 9 | 15 | – |
1296 | 198.845 72 | 35.173 51 | 0.023 09 | 8.90 | 8.12 | 1.82 | 8.98 | 0.19 | 19 | 12 | 22 | 7.1 |
1298 | 198.670 04 | 35.036 38 | 0.023 74 | 8.67 | 7.46 | 1.61 | 9.21 | 0.28 | 22 | 14 | 29 | 13.2 |
1323 | 203.28 55 | 40.853 07 | 0.024 00 | 8.88 | 7.70 | 1.24 | 8.97 | 0.33 | 10 | 22 | 33 | 3.7 |
1407 | 212.509 86 | 38.708 12 | 0.025 76 | 9.86 | 8.31 | 3.81 | 9.67 | 0.21 | 34 | 28 | 52 | – |
1410 | 212.677 58 | 38.718 42 | 0.025 61 | 8.57 | 7.42 | 1.30 | 9.26 | 0.18 | 23 | 19 | 47 | – |
1411 | 212.627 10 | 38.739 50 | 0.026 06 | 8.95 | 7.86 | 1.23 | 9.44 | 0.15 | 29 | 16 | 31 | 12.5 |
1414 | 212.695 82 | 38.759 70 | 0.025 70 | 8.74 | 7.46 | 1.72 | 8.81 | 0.14 | 15 | 11 | 25 | – |
1415 | 212.729 23 | 38.785 92 | 0.025 80 | 8.43 | 7.14 | 1.54 | 9.13 | 0.13 | 14 | 15 | 31 | 7.2 |
1533 | 241.434 11 | 36.275 08 | 0.031 23 | 9.40 | 7.50 | 1.74 | 9.79 | 0.30 | 44 | 23 | 38 | – |
1554 | 242.242 89 | 36.610 88 | 0.030 14 | 11.02 | 8.83 | 3.33 | 10.42 | 0.31 | 26 | 50 | 104 | 26.6 |
1605 | 246.164 76 | 41.019 95 | 0.027 12 | 8.79 | 7.33 | 0.66 | 9.70 | 0.10 | 33 | 15 | 31 | 6.1 |
1632 | 246.062 71 | 41.110 62 | 0.029 26 | 9.97 | 8.21 | 3.27 | 9.70 | 0.22 | 38 | 17 | 33 | 9.6 |
1639 | 246.708 60 | 40.917 86 | 0.029 15 | 8.93 | 7.68 | 1.83 | 9.21 | 0.34 | 21 | 29 | 33 | 9.0 |
1643 | 246.130 86 | 40.684 45 | 0.029 43 | 8.80 | 7.49 | 1.10 | 9.06 | 0.28 | 20 | 18 | 36 | – |
1647 | 246.084 27 | 40.865 01 | 0.030 00 | 9.34 | 7.50 | 2.46 | 9.13 | 0.16 | 17 | 12 | 44 | – |
1648 | 245.998 46 | 41.138 17 | 0.030 29 | 9.08 | 7.39 | 1.34 | 9.59 | 0.27 | 34 | 17 | 33 | 20.6 |
1663 | 250.622 96 | 42.262 85 | 0.027 50 | 8.78 | 7.27 | 1.27 | 9.08 | 0.14 | 20 | 16 | 32 | 15.6 |
1669 | 250.562 63 | 42.059 96 | 0.027 80 | 8.82 | 7.68 | 1.96 | 9.17 | 0.22 | 20 | 18 | 50 | 19.7 |
1700 | 251.488 97 | 39.985 83 | 0.030 20 | 10.17 | 8.22 | 3.18 | 9.69 | 0.36 | 5 | 20 | 35 | 7.2 |
1713 | 251.873 96 | 40.565 70 | 0.031 08 | 8.92 | 7.44 | 1.39 | 9.68 | 0.32 | 37 | 19 | 32 | – |
1725 | 258.806 17 | 30.451 46 | 0.028 64 | 9.98 | 8.17 | 2.56 | 9.66 | 0.31 | 39 | 20 | 34 | – |
1774 | 259.682 21 | 58.135 13 | 0.029 08 | 10.95 | 8.85 | 3.60 | 9.98 | 0.39 | 55 | 26 | 48 | 13.5 |
1795 | 258.779 94 | 58.240 45 | 0.031 01 | 10.20 | 8.35 | 3.08 | 9.78 | 0.26 | 40 | 18 | 38 | – |
1907 | 262.173 43 | 57.114 76 | 0.028 12 | – | – | −0.42 | 9.03 | 0.03 | 17 | 11 | 23 | 16.7 |
ID . | RA . | Dec. . | z . | log M* . | μ* . | NUV−r . | |$\log M_{\rm H\,{}\small {I}}$| . | Dis . | R1 . | |$R_{\rm 50,H\,\small {I}}$| . | |$R_{\rm 90,H\,\small {I}}$| . | rs . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
. | . | . | . | (M⊙) . | (M⊙kpc− 2) . | . | (M⊙) . | (degree) . | (arcsec) . | (arcsec) . | (arcsec) . | (arcsec) . |
14 | 112.319 34 | 42.279 63 | 0.023 07 | 10.39 | 8.33 | 2.87 | 9.88 | 0.30 | 61 | 31 | 57 | 3.8 |
78 | 123.488 52 | 52.648 47 | 0.018 20 | 11.01 | 8.99 | 3.80 | 10.40 | 0.22 | 140 | 63 | 132 | 16.4 |
84 | 123.039 66 | 52.455 24 | 0.018 74 | 9.61 | 8.14 | 2.03 | 9.55 | 0.16 | 46 | 23 | 41 | – |
143 | 127.303 50 | 40.854 48 | 0.025 10 | 9.33 | 7.74 | 2.49 | 8.77 | 0.21 | 16 | 12 | 21 | 37.0 |
179 | 127.734 92 | 55.835 17 | 0.025 42 | 8.91 | 7.53 | 2.56 | 8.73 | 0.39 | 15 | 11 | 21 | 6.1 |
221 | 129.177 48 | 41.472 31 | 0.029 19 | 9.88 | 8.29 | 1.94 | 9.80 | 0.08 | 42 | 24 | 46 | 11.9 |
248 | 129.803 26 | 30.923 83 | 0.025 69 | 8.51 | 7.10 | 2.03 | 9.19 | 0.19 | 23 | 17 | 31 | 15.4 |
306 | 132.052 04 | 36.780 74 | 0.025 27 | 10.24 | 8.49 | 2.52 | 9.46 | 0.24 | 32 | 16 | 29 | 4.1 |
307 | 132.666 60 | 36.468 76 | 0.025 21 | 6.98 | 6.98 | 1.51 | 9.94 | 0.35 | 57 | 25 | 55 | – |
346 | 132.028 70 | 41.859 22 | 0.029 97 | 10.11 | 7.99 | 2.64 | 9.53 | 0.26 | 32 | 21 | 36 | – |
370 | 137.219 30 | 44.932 28 | 0.026 57 | 10.27 | 9.31 | 3.62 | 8.96 | 0.13 | 14 | 14 | 43 | 7.9 |
375 | 137.337 53 | 45.039 75 | 0.027 30 | 8.89 | 7.25 | 1.63 | 9.55 | 0.26 | 37 | 17 | 31 | 7.3 |
394 | 138.209 27 | 40.498 74 | 0.027 59 | 9.60 | 8.03 | 2.17 | 9.73 | 0.41 | 37 | 18 | 37 | 7.4 |
396 | 138.393 33 | 40.465 74 | 0.027 58 | 8.59 | 7.12 | 1.93 | 9.34 | 0.35 | 27 | 16 | 26 | 4.8 |
444 | 138.374 36 | 51.315 19 | 0.027 73 | 8.80 | 7.25 | – | 9.33 | 0.23 | 25 | 13 | 27 | 28.8 |
446 | 138.537 51 | 51.417 97 | 0.028 05 | 9.51 | 8.59 | – | 9.17 | 0.14 | 21 | 14 | 32 | 8.7 |
454 | 138.843 23 | 51.050 39 | 0.028 81 | 9.68 | 7.78 | 2.41 | 9.45 | 0.32 | 31 | 19 | 28 | 4.3 |
482 | 139.359 35 | 45.971 74 | 0.025 74 | 9.45 | 7.89 | 2.80 | 8.49 | 0.20 | 6 | 14 | 28 | 22.2 |
483 | 139.559 19 | 45.651 71 | 0.026 90 | 10.70 | 8.47 | 2.87 | 10.16 | 0.30 | 68 | 35 | 61 | 5.0 |
517 | 139.904 99 | 32.353 20 | 0.026 52 | 9.72 | 8.54 | 2.01 | 9.25 | 0.23 | 24 | 18 | 45 | 11.3 |
563 | 141.202 93 | 49.398 27 | 0.027 23 | 9.73 | 8.27 | 3.30 | 8.72 | 0.24 | 15 | 10 | 19 | – |
773 | 153.034 46 | 46.293 71 | 0.024 25 | 10.34 | 8.48 | 2.63 | 10.03 | 0.40 | 47 | 34 | 66 | – |
776 | 152.849 76 | 45.735 39 | 0.023 75 | 8.69 | 7.20 | 1.60 | 8.88 | 0.23 | 19 | 12 | 21 | – |
840 | 153.807 16 | 56.603 31 | 0.026 67 | 8.82 | 7.43 | 1.24 | 9.41 | 0.07 | 28 | 17 | 33 | 8.9 |
889 | 154.253 28 | 55.880 05 | 0.024 37 | 9.77 | 8.28 | 2.34 | 9.56 | 0.28 | 36 | 18 | 33 | 6.7 |
941 | 153.811 51 | 58.691 74 | 0.022 95 | 8.61 | 7.73 | 1.80 | 9.12 | 0.29 | 6 | 29 | 49 | 4.5 |
983 | 162.506 34 | 36.256 77 | 0.021 90 | 9.75 | 8.09 | 3.12 | 8.47 | 0.09 | 6 | 17 | 27 | – |
997 | 162.754 26 | 36.192 58 | 0.023 80 | 9.85 | 7.80 | 2.23 | 9.98 | 0.23 | 55 | 23 | 47 | – |
999 | 162.494 49 | 36.414 99 | 0.023 27 | 9.50 | 8.20 | 3.34 | 8.78 | 0.08 | 17 | 13 | 24 | 5.7 |
1020 | 166.868 89 | 35.463 65 | 0.028 28 | – | – | 3.05 | 9.87 | 0.10 | 37 | 26 | 58 | – |
1022 | 166.959 02 | 35.402 99 | 0.028 40 | 10.47 | 8.81 | 3.49 | 9.56 | 0.07 | 36 | 18 | 32 | 18.0 |
1024 | 166.958 21 | 35.684 83 | 0.028 46 | 10.30 | 9.10 | 2.97 | 9.62 | 0.22 | 41 | 25 | 42 | 9.1 |
1027 | 167.105 16 | 35.330 68 | 0.028 88 | 8.96 | 7.33 | 3.81 | 8.94 | 0.16 | 18 | 13 | 25 | – |
1042 | 168.529 72 | 34.308 86 | 0.025 26 | 8.70 | 6.97 | 1.91 | 9.09 | 0.16 | 25 | 18 | 31 | 17.1 |
1104 | 177.575 56 | 35.254 09 | 0.021 28 | 10.22 | 8.97 | 2.84 | 10.08 | 0.36 | 68 | 35 | 76 | – |
1143 | 185.610 22 | 40.761 68 | 0.022 92 | 8.40 | 7.68 | −0.14 | 9.14 | 0.17 | 28 | 16 | 27 | 16.9 |
1183 | 193.237 60 | 51.826 84 | 0.027 62 | 8.58 | 7.78 | 1.50 | 8.90 | 0.20 | 16 | 11 | 22 | 23.2 |
1230 | 196.763 12 | 57.865 14 | 0.028 74 | 8.77 | 7.04 | 2.04 | 9.09 | 0.27 | 19 | 12 | 22 | 4.6 |
1254 | 198.423 30 | 47.299 23 | 0.028 08 | 8.80 | 7.20 | 1.22 | 9.19 | 0.20 | 23 | 15 | 25 | 6.3 |
1259 | 198.260 18 | 47.345 18 | 0.028 41 | 8.76 | 7.28 | 1.79 | 9.02 | 0.11 | 17 | 14 | 30 | 10.4 |
1261 | 197.860 26 | 47.440 52 | 0.028 61 | 9.03 | 7.29 | 2.46 | 8.92 | 0.25 | 15 | 9 | 15 | – |
1296 | 198.845 72 | 35.173 51 | 0.023 09 | 8.90 | 8.12 | 1.82 | 8.98 | 0.19 | 19 | 12 | 22 | 7.1 |
1298 | 198.670 04 | 35.036 38 | 0.023 74 | 8.67 | 7.46 | 1.61 | 9.21 | 0.28 | 22 | 14 | 29 | 13.2 |
1323 | 203.28 55 | 40.853 07 | 0.024 00 | 8.88 | 7.70 | 1.24 | 8.97 | 0.33 | 10 | 22 | 33 | 3.7 |
1407 | 212.509 86 | 38.708 12 | 0.025 76 | 9.86 | 8.31 | 3.81 | 9.67 | 0.21 | 34 | 28 | 52 | – |
1410 | 212.677 58 | 38.718 42 | 0.025 61 | 8.57 | 7.42 | 1.30 | 9.26 | 0.18 | 23 | 19 | 47 | – |
1411 | 212.627 10 | 38.739 50 | 0.026 06 | 8.95 | 7.86 | 1.23 | 9.44 | 0.15 | 29 | 16 | 31 | 12.5 |
1414 | 212.695 82 | 38.759 70 | 0.025 70 | 8.74 | 7.46 | 1.72 | 8.81 | 0.14 | 15 | 11 | 25 | – |
1415 | 212.729 23 | 38.785 92 | 0.025 80 | 8.43 | 7.14 | 1.54 | 9.13 | 0.13 | 14 | 15 | 31 | 7.2 |
1533 | 241.434 11 | 36.275 08 | 0.031 23 | 9.40 | 7.50 | 1.74 | 9.79 | 0.30 | 44 | 23 | 38 | – |
1554 | 242.242 89 | 36.610 88 | 0.030 14 | 11.02 | 8.83 | 3.33 | 10.42 | 0.31 | 26 | 50 | 104 | 26.6 |
1605 | 246.164 76 | 41.019 95 | 0.027 12 | 8.79 | 7.33 | 0.66 | 9.70 | 0.10 | 33 | 15 | 31 | 6.1 |
1632 | 246.062 71 | 41.110 62 | 0.029 26 | 9.97 | 8.21 | 3.27 | 9.70 | 0.22 | 38 | 17 | 33 | 9.6 |
1639 | 246.708 60 | 40.917 86 | 0.029 15 | 8.93 | 7.68 | 1.83 | 9.21 | 0.34 | 21 | 29 | 33 | 9.0 |
1643 | 246.130 86 | 40.684 45 | 0.029 43 | 8.80 | 7.49 | 1.10 | 9.06 | 0.28 | 20 | 18 | 36 | – |
1647 | 246.084 27 | 40.865 01 | 0.030 00 | 9.34 | 7.50 | 2.46 | 9.13 | 0.16 | 17 | 12 | 44 | – |
1648 | 245.998 46 | 41.138 17 | 0.030 29 | 9.08 | 7.39 | 1.34 | 9.59 | 0.27 | 34 | 17 | 33 | 20.6 |
1663 | 250.622 96 | 42.262 85 | 0.027 50 | 8.78 | 7.27 | 1.27 | 9.08 | 0.14 | 20 | 16 | 32 | 15.6 |
1669 | 250.562 63 | 42.059 96 | 0.027 80 | 8.82 | 7.68 | 1.96 | 9.17 | 0.22 | 20 | 18 | 50 | 19.7 |
1700 | 251.488 97 | 39.985 83 | 0.030 20 | 10.17 | 8.22 | 3.18 | 9.69 | 0.36 | 5 | 20 | 35 | 7.2 |
1713 | 251.873 96 | 40.565 70 | 0.031 08 | 8.92 | 7.44 | 1.39 | 9.68 | 0.32 | 37 | 19 | 32 | – |
1725 | 258.806 17 | 30.451 46 | 0.028 64 | 9.98 | 8.17 | 2.56 | 9.66 | 0.31 | 39 | 20 | 34 | – |
1774 | 259.682 21 | 58.135 13 | 0.029 08 | 10.95 | 8.85 | 3.60 | 9.98 | 0.39 | 55 | 26 | 48 | 13.5 |
1795 | 258.779 94 | 58.240 45 | 0.031 01 | 10.20 | 8.35 | 3.08 | 9.78 | 0.26 | 40 | 18 | 38 | – |
1907 | 262.173 43 | 57.114 76 | 0.028 12 | – | – | −0.42 | 9.03 | 0.03 | 17 | 11 | 23 | 16.7 |
4 RESULTS
The mass distribution for our final sample is shown in Fig. 4. The sample is divided into four subsamples: the BTG, the CTG, the additional galaxies located in blue cubes (BUG) and the additional galaxies located in control cubes (CUG). By selection, all targeted galaxies are massive with log M*/M⊙ > 10. The additional galaxies have a very broad stellar mass distribution from 108 to 1011 M⊙. The goal of this paper is to study their H i properties.
4.1 H i mass–size relation
The tight relation between the diameter of the H i disc and the total H i mass in galaxies was investigated by Broeils & Rhee (1997). Later, it was found that this relation changes very little for different kinds of galaxies (Swaters et al. 2002; Noordermeer et al. 2005). Fig. 5 shows the H i mass–size relation for our sample. The left-hand panel shows this relation for the four subsamples: BTG (blue), CTG (red), BUG (green) and CUG (purple). The black line is from Broeils & Rhee (1997). The right-hand panel shows the same relation for different stellar mass ranges. Some outliers far from this relation are marked by their IDs.
Almost all the galaxies closely obey this relation, which is consistent with the result of Paper I. This relation is similarly tight for galaxies with both high and low stellar masses: the average column density of H i is about same for all spiral galaxies. Wang et al. (2014) suggest that this relation is primarily a result of atomic-to-molecular gas conversion in the inner disc and is further enhanced by a homogeneous radial distribution of H i density in the outer disc of galaxies. We will investigate the nature of the handful of outliers later in the paper.
4.2 H i-optical scaling relations
In Fig. 6, we plot the H i-to-stellar mass ratio as a function of stellar mass, stellar surface mass density and NUV−r colour for our sample. The H i mass fraction correlates with stellar mass, surface mass density and NUV−r, and extends the mean relations quantified for normal galaxies with stellar masses greater than 1010 M⊙ in former studies (Catinella et al. 2010; Cortese et al. 2011; Huang et al. 2012). We do not see different H i scaling relations for galaxies in the data cubes with a central targeted H i excess galaxy and data cubes with a central targeted control galaxy.
We plot the H i plane linking H i-to-stellar mass ratio with stellar surface mass density and NUV−r colour defined by Catinella et al. (2010) in the left-hand panel of Fig. 7. The grey data points represent galaxies from GASS (Catinella et al. 2010). In this projection, both targeted and untargeted galaxies lie close to the H i plane. Differences arise when we focus on the displacement from the plane. As already found in Paper I, we observe a tilt of our observed galaxies with respect to the diagonal of the plot. The plane underpredicts the H i content of all observed galaxies at the high-H i-fraction end and slightly overpredicts it at the low-H i-fraction end of our sample. The underprediction at the high-H i-fraction end is discussed in detail by Li et al. (2012), who argue that the addition of additional parameters yield a more unbiased prediction of H i content.
The right-hand panel of Fig. 7 shows the distributions of the deviations from the H i-plane (the black line in Fig. 7). We find a significant difference between the distributions of the galaxies in the cubes of the H i-rich targets and the galaxies in the control cubes. We perform a Kolmogorov–Smirnov (K–S) test to quantify this significance, and obtain a probability of 0.041, suggesting a 96 per cent significance for the null hypothesis of the two samples being drawn from the same parent distribution to be rejected. It appears that on average, galaxies in the data cubes with an H i excess targeted galaxy do on average contain more H i (relative to their surface mass density and colour) than galaxies in the cubes containing a control galaxy. This suggests that galaxies associated with blue targeted galaxies are also likely to be gas rich. This supports the observation pointed out by Kauffmann, Li & Heckman (2010), see also Weinmann et al. (2006), who found that there is more photometrically estimated H i in satellites around more star-forming primary galaxies than in satellites around less star-forming primary galaxies. In the following, we refer to this as ‘H i conformity’. Those authors argued that the satellites trace a large-scale gas reservoir that is accreted on to the central galaxies.
Next, we repeat the morphological analysis of Paper I for the additional galaxies detected in the cubes. In Fig. 8, we plot distributions of ΔCenter, |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$|, rs and rs/R1. ΔCenter is calculated as the distance between the H i centre and the r-band centre, normalized by the semi-major axis of the H i ellipse. |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| describes the concentration/extension of the H i discs. rs is the exponentially scalelength of H i discs.
The galaxies in the H i-rich cubes do not differ from those in the control cubes in their distribution of ΔCenter. However, their distributions of |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| do show a significant difference. Galaxies in the H i-rich cubes tend to have larger |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| than in the control cubes. If we investigate galaxies with |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| greater than 2.0, we find almost all of them have more H i gas than the predicted by their optical properties. The distribution of the deviations from the H i-plane for these galaxies is shown in Fig. 9. The median value of the deviations is 0.44 dex, which means these galaxies have 2.7 times H i of the predicted values in general. We also find their H i to extend far beyond the optical disc. The rs and rs/R1 distributions of the galaxies in the H i-rich cubes do not differ significantly from those for galaxies in the control cubes.
To assess whether the density of the environment may play a role in these differences, we checked the number of SDSS spectroscopically observed galaxies of which fall in our cubes, but which have no H i detections. There are 95 galaxies with no H i detections in the H i-rich cubes and 295 galaxies with no H i detections in the control cubes. Most of these galaxies have stellar masses in the range between 108 M⊙ and 1010 M⊙. We also quantify the environment by using the 3D reconstructed matter overdensity based on SDSS DR7 data set (Jasche et al. 2010), which is defined as |$\delta =(\rho -\bar{\rho })/\bar{\rho }$|, where ρ is the matter density and |$\bar{\rho }$| is the mean matter density. Thus, the mean overdensity of galaxies in control cubes is 10.7, while the mean overdensity of galaxies in blue cubes is 4.6. It is clear that the control cubes are located in denser regions than the H i-rich cubes, and the fraction of optically-identified galaxies that have detectable H i masses is much higher in the blue cubes than in the control cubes. This may indicate that H i conformity is closely related to the environment of the galaxy.
5 MORPHOLOGY OF OUTLIERS
Galaxies accrete cold gas directly from the IGM or through interaction with companions, and lose their gas through tidal or ram-pressure stripping. Some authors have tried to connect specific H i structures in galaxies with ongoing cold gas accretion, such as the existence of extraplanar gas and warped structures of H i distribution in galaxies (Thilker et al. 2007; Wakker et al. 2007; Oosterloo et al. 2010). Ram-pressure striping, especially in clusters also affect the morphology of H i discs (McConnachie et al. 2007; Bernard et al. 2012; Serra et al. 2013; Zhang et al. 2013). In this section, we investigate the structures of those galaxies which are outliers in the H i mass–size relation (see Fig. 5) or the H i-plane (see Fig. 7). We argue that (after close inspection) either offset is an indication for ongoing interaction with the environment.
Outliers are defined to include galaxies that are offset in their H i mass by more than 0.4 dex from the normal H i mass–size relation or offset more than 0.5 dex from the H i-plane. Here, we just discuss the outliers with |$M_{*}>M_{\rm H\,\small {I}}$|, since the H i plane would underestimate the H i fraction for galaxies with |$\log _{10}(M_{*}/M_{\rm H\,\small {I}})>0$|. We select the outliers from all cubes with ‘peculiar cubes’ (Section 3) excluded. Note that there is no indication that outliers tend to fall preferentially into either group of galaxies around H i-rich galaxies (blue sample) or control galaxies. In Table 2, we list the environment of galaxies, host system dark matter mass, offset from the H i mass–size relation, offset from the H i-plane, ΔCenter and |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$|. The environment of galaxies (isolated or in group) and the host halo mass estimates are from Yang et al. (2007). Fig. 10 shows H i total intensity contours overlaid on an SDSS colour image, an H i velocity field and an SDSS spectrum for each of these outliers. The white, green, red and yellow H i contours represent 2.0, 4.0, 14.0 and 20.0 times the median SNR of the outermost H i contour, respectively. The velocity fields are derived from a Gauss–Hermite fitting procedure (den Heijer et al., in preparation).
ID . | Environment . | log10Mhalo . | H i MS . | H i-plane . | ΔCenter . | |$R_{\rm 90,H\,\small {I}}/$| . |
---|---|---|---|---|---|---|
. | . | M⊙ . | dex . | dex . | . | |$R_{\rm 50,H\,\small {I}}$| . |
941 | Isolated | – | 1.15 | 0.65 | 0.252 | 1.68 |
1323 | – | – | 0.51 | 0.08 | 0.3981 | 1.51 |
1554 | Isolated | 12.59 | 0.97 | 0.27 | 0.350 | 2.09 |
1700 | Isolated | – | 1.63 | 0.15 | 0.960 | 1.73 |
890 | Isolated | 12.37 | −0.14 | −0.87 | 0.447 | 1.85 |
983 | Isolated | – | 0.55 | −0.70 | 0.517 | 1.52 |
1104 | Isolated | – | 0.09 | 0.66 | 0.129 | 2.16 |
1378 | Isolated | 12.37 | −0.02 | −0.50 | 0.320 | 1.76 |
1407 | – | – | 0.12 | 0.62 | 0.517 | 1.87 |
ID . | Environment . | log10Mhalo . | H i MS . | H i-plane . | ΔCenter . | |$R_{\rm 90,H\,\small {I}}/$| . |
---|---|---|---|---|---|---|
. | . | M⊙ . | dex . | dex . | . | |$R_{\rm 50,H\,\small {I}}$| . |
941 | Isolated | – | 1.15 | 0.65 | 0.252 | 1.68 |
1323 | – | – | 0.51 | 0.08 | 0.3981 | 1.51 |
1554 | Isolated | 12.59 | 0.97 | 0.27 | 0.350 | 2.09 |
1700 | Isolated | – | 1.63 | 0.15 | 0.960 | 1.73 |
890 | Isolated | 12.37 | −0.14 | −0.87 | 0.447 | 1.85 |
983 | Isolated | – | 0.55 | −0.70 | 0.517 | 1.52 |
1104 | Isolated | – | 0.09 | 0.66 | 0.129 | 2.16 |
1378 | Isolated | 12.37 | −0.02 | −0.50 | 0.320 | 1.76 |
1407 | – | – | 0.12 | 0.62 | 0.517 | 1.87 |
ID . | Environment . | log10Mhalo . | H i MS . | H i-plane . | ΔCenter . | |$R_{\rm 90,H\,\small {I}}/$| . |
---|---|---|---|---|---|---|
. | . | M⊙ . | dex . | dex . | . | |$R_{\rm 50,H\,\small {I}}$| . |
941 | Isolated | – | 1.15 | 0.65 | 0.252 | 1.68 |
1323 | – | – | 0.51 | 0.08 | 0.3981 | 1.51 |
1554 | Isolated | 12.59 | 0.97 | 0.27 | 0.350 | 2.09 |
1700 | Isolated | – | 1.63 | 0.15 | 0.960 | 1.73 |
890 | Isolated | 12.37 | −0.14 | −0.87 | 0.447 | 1.85 |
983 | Isolated | – | 0.55 | −0.70 | 0.517 | 1.52 |
1104 | Isolated | – | 0.09 | 0.66 | 0.129 | 2.16 |
1378 | Isolated | 12.37 | −0.02 | −0.50 | 0.320 | 1.76 |
1407 | – | – | 0.12 | 0.62 | 0.517 | 1.87 |
ID . | Environment . | log10Mhalo . | H i MS . | H i-plane . | ΔCenter . | |$R_{\rm 90,H\,\small {I}}/$| . |
---|---|---|---|---|---|---|
. | . | M⊙ . | dex . | dex . | . | |$R_{\rm 50,H\,\small {I}}$| . |
941 | Isolated | – | 1.15 | 0.65 | 0.252 | 1.68 |
1323 | – | – | 0.51 | 0.08 | 0.3981 | 1.51 |
1554 | Isolated | 12.59 | 0.97 | 0.27 | 0.350 | 2.09 |
1700 | Isolated | – | 1.63 | 0.15 | 0.960 | 1.73 |
890 | Isolated | 12.37 | −0.14 | −0.87 | 0.447 | 1.85 |
983 | Isolated | – | 0.55 | −0.70 | 0.517 | 1.52 |
1104 | Isolated | – | 0.09 | 0.66 | 0.129 | 2.16 |
1378 | Isolated | 12.37 | −0.02 | −0.50 | 0.320 | 1.76 |
1407 | – | – | 0.12 | 0.62 | 0.517 | 1.87 |
5.1 Outliers in the H i mass–size relation
Galaxies marked 941, 1323, 1554 and 1700 are outliers from the H i mass–size relation. Galaxy 1554 and 1700 are edge-on galaxies, while Galaxy 941, 1323 and 1622 are not. We will discuss Galaxy 941, 1323, 1554 and 1700 in detail. Galaxy 983 is investigated in next subsection because it is also offset from the H i Fundamental Plane.
Galaxy 941 and 1323 are both starburst dwarf galaxies, but most of their H i is distributed asymmetrically, and is also offset from the optical discs. The H i of Galaxy 941 is distributed in patches that extend 10 times further than the optical discs. The nearby object seen in the SDSS image, is found to be a foreground star. The H i disc of Galaxy 1323 shows a big void in the region of the optical disc. There are two possible explanations for these disturbed morphologies. One is feedback processes (by AGN or by superwinds powered by SNe and stellar winds in the starburst) that push gas from inside the galaxy to the outside. The other explanation is that the H i gas in the stellar disc regions have been converted to molecular gas to sustain the fast star formation, while the H i gas in the outer regions has not had enough time to flow into the stellar disc. The stellar masses of the galaxies and their position on the ‘Baldwin, Phillips & Terlevich’ diagram suggests that they do not have AGNs in their cores. We check the star formation time-scale for these two galaxies. It would take more than 0.4 Gyr to consume 10 per cent of their total H i gas with the current star formation rate. We conclude that SNe explosions and stellar winds are the most likely cause for the holes in the H i intensity maps. In similar case, Mühle et al. (2005) argued that a huge hole in H i distribution of NGC 1569 is probably driven from SNe feedback in the centre of the galaxy over the past 20 Myr.
Galaxy 1554 and 1700 are edge-on galaxies. As can be seen from the SDSS spectrum, the dust extinction is very high in Galaxy 1554. The H i gas is concentrated and distributed in the stellar disc. Galaxy 1700 is a star-forming galaxy in which the H i seems to be vertically offset with respect to the stellar disc. The inclination correction creates significant uncertainty when calculating H i sizes for edge-on galaxies, since the H i discs are usually thicker than stellar discs. This may result in the offset in the H i mass–size relation.
5.2 Outliers from the H i-plane
Galaxy 983 exhibits a large offset from both the H i mass–size relation and the H i-plane. While it appears to be H i deficient with respect to the plane, its H i is more concentrated than predicted by the H i mass–size relation. In addition, a significant part of its H i appears to show irregular kinematics and is offset from the galaxy disc. Hence, morphology and kinematics suggest recent tidal or ram-pressure stripping to have removed gas in the outskirts of the galaxy.
Galaxy 890 has its H i gas compressed against the stellar disc on one side and extended to larger radius on the opposite side. Its morphological H i and optical centres are distinctly offset from each other. This is very similar to the ram-pressure stripped galaxies observed in clusters (Koopmann & Kenney 2004; Vollmer et al. 2004; Crowl et al. 2005; Chung et al. 2009). The observed H i gas mass is just 12 per cent of the predicted value. The velocity map shows a nice spider diagram in the optical region, marked in black ellipse (see Fig. 10). For the west extended part, which also contains most of the H i, it shows a clear decrease in velocity from the inner region to the outer region. So it is likely that the direction of ram-pressure stripping is from east to west and from far to near.
Galaxy 1104 and Galaxy 1407 have at least three times more H i than predicted (see Fig. 7). Galaxy 1104 is a warped edge-on galaxy with a high warp amplitude. The H i distribution is also rather asymmetric, suggesting a recent interaction. Galaxy 1407 is a star-forming galaxy with a large amount of H i offset from the regularly rotating disc. It seems to be interacting with two close companions.
Galaxy 1378 has less H i gas than predicted and its H i gas is highly lopsided. It is an isolated galaxy with strong ongoing star formation at the centre. This galaxy possesses a large amount of gas outside the regularly rotating disc, suggesting ram-pressure stripping or tidal stripping of H i from the galaxy.
For comparison, we also present a set of ‘non-outlier’ galaxies in Fig. 11. These are selected randomly from our sample galaxies with both the offset to H i mass–size relation and the offset to H i-plane less than 0.2 dex. Generally speaking, the H i shapes of these non-outliers are more regular compared to the H i shapes of outliers. Most of them are less asymmetric and have less H i-gas clouds in their outer region, which suggests no violent interaction with IGM. The comparison between Figs 10 and 11 confirms that most of the outliers really have very irregular H i morphologies.
Fig. 12 compares ΔCenter (left-hand panel) and |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| (right-hand panel) between outliers and non-outliers. Note that the non-outlier sample includes all the non-outliers defined in the same way as above, not only those shown in Fig. 11. The outliers appear to have larger ΔCenter and smaller |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| when compared to the non-outliers. This result is consistent with the conclusion above, which are drawn from the example H i maps in Fig. 11. However, given the small sample size and the resulting poor statistics indicated by the K–S tests (see the K–S probabilities quoted in the figure), this result should not be overemphasized. We list ΔCenter and |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| for the outliers in Table 2. Galaxy 1700 has very large ΔCenter (∼0.9) that is consistent with its clearly biased H i distribution. Galaxy 1407 and 983 have relatively large ΔCenter (∼0.5), which are attributed to their extraplanar gas. Galaxy 1104,1554 and 1407 have the largest |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$| among others. Their location on H i-plane are all above the mean relation. This is consistent with what we find in Fig. 9. However, we do not compare rs and rs/R1 for the outliers, as their rs cannot be well determined.
6 SUMMARY AND DISCUSSION
In this paper, we present a catalogue of galaxies from the Bluedisk H i galaxy survey that includes sources within the cubes that were not specifically targeted for observation. These galaxies are nevertheless very interesting, because they probe the environments of unusually H i-rich galaxies, as well as a control sample of galaxies with similar masses and structural properties, but with more normal H i content.
We present the distribution of H i morphological parameters, the H i mass–size relation and scaling relations between H i gas mass fraction and galaxy mass, structure and colour. The main results in this work are listed below.
Our sample follows established H i scaling relations as function of stellar mass, stellar surface density and colour very well, and fits the H i mass–size relation, except for a few outliers.
Galaxies in the H i-rich cubes are displaced to higher H i gas mass fractions than predicted by the optical properties, compared to galaxies in the control cubes.
We inspect the H i intensity maps and velocity fields of the outliers from the H i mass–size relation and the plane. We find that all these galaxies are likely to have undergone recent interaction with their environment.
The phenomenon of galactic conformity was first discovered by Weinmann et al. (2006), who argued that the properties of satellite galaxies are strongly correlated with those of their central galaxies. In particular, early-type central galaxies have a larger fraction of early-type satellites than late-type central galaxies with the same stellar mass. Subsequently, Kauffmann et al. (2010) found that the total mass of gas in satellites has a strong correlation with the colours and specific star formation rates of central galaxies of all stellar masses, and that this correlation extends out to radii of 1 Mpc or more. This suggests that more gas-rich galaxies should have more gas in satellites in their immediate surroundings. This work was, however, based on optical proxies for H i content and not on real H i data. In this paper, we find that galaxies in the large-scale environment of H i-rich targeted galaxies tend to be H i-rich and to have a larger |$R_{\rm 90,H\,\small {I}}/R_{\rm 50,H\,\small {I}}$|. Our findings thus support the conjectures presented in Kauffmann et al. (2010).
Weinmann et al. (2006) and Ann, Park & Choi (2008) argued that the X-ray-emitting hot gas of host early-type central galaxies can deprive their satellites of their gas reservoirs through hydrodynamic interactions. However, this cannot explain the conformity effect in low-mass haloes. Kauffmann et al. (2010) argued that satellite galaxies trace the high-density peaks of underlying reservoir of ionized gas, which provides fuel for star formation in central galaxies.
In this work, we have been able to study a few galaxies which have irregular H i shapes and anomalous H i gas content. In most cases, we find signatures of interaction with the environment that is suggestive of tidal or ram-pressure stripping, though two galaxies are found (1407 and 1104) that may be accreting H i clouds.
EW and CL would like to thank the hospitality of the Max Planck Institute for Astrophysics while this work was being initiated. EW is grateful to Paolo Serra and Zhixiong Liang for helpful discussion on data analysis progress, to Milan den Heijer for providing the Gauss–Hermite velocity maps, and to Attila Popping for readily providing his primary beam attenuation model. This work is supported by National Key Basic Research Programme of China (no. 2015CB857004), NSFC (grant no. 11173045, 11233005, 11325314, 11320101002), the Strategic Priority Research Programme ‘The Emergence of Cosmological Structures’ of CAS (grant no. XDB09000000) and the exchange programme between CAS and the Max Panck Society.
Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory and the University of Washington.
At a column density limit of zero, the H i flux fraction is larger than 1.0 for all galaxies, because by clipping at that level, the noise contribution is neglected (i.e. some negative total flux from negative noise peaks has to be added to counterweight this effect at the edges of the detected sources.