H I Observations of Five Groups of Galaxies

Freeland, Emily; Stilp, Adrienne M.; Wilcots, Eric M.

doi:10.1088/0004-6256/138/1/295

Cited by 47 publications

(66 citation statements)

References 46 publications

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“…Prior evidence for preprocessing of the gas content in the group environment comes from estimates of the H I mass function (HIMF) which historically have been derived from individual groups or small group samples (e.g. Verheijen et al 2000;de Blok et al 2002;Kovac et al 2005;Freeland et al 2009;Kilborn et al 2009;Pisano et al 2011;Hess 2011). Despite the small number statistics, calculations of the group HIMF reliably suggest a flatter slope at the low mass end than the field or global HIMF.…”

Section: Halo Occupation Distributionmentioning

confidence: 99%

“…While Freeland et al (2009) found that groups with a mix of morphological types exhibit more signs of recent tidal interactions than groups dominated by one morphological type. Thus, collectively and over varying timescales, gravitational and to a lesser extent, hydrodynamical interactions can also transform galaxies from blue, star-forming, gas rich objects to red, passively evolving, gas poor objects in groups.…”

Section: Introductionmentioning

confidence: 95%

“…Gavazzi et al 2006;Chung et al 2009), although a growing num-ber of studies also examine H I in well defined intermediate group environments (e.g. Pisano et al 2007;Kern et al 2008;Freeland et al 2009;Kilborn et al 2009;Rasmussen et al 2012;Mihos et al 2012). These studies have shown that galaxies in the dense cluster environment tend to be H I deficient (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…In any case, population studies derived from small samples of groups consistently show that the group H I mass function (HIMF) is flatter than the global HIMF, revealing either a paucity of low gas-mass galaxies or simply hinting that denser environments are harsh on low gas-mass galaxies (Verheijen et al 2000;de Blok et al 2002;Kovac et al 2005;Freeland et al 2009;Kilborn et al 2009;Pisano et al 2011;Hess 2011). While Freeland et al (2009) found that groups with a mix of morphological types exhibit more signs of recent tidal interactions than groups dominated by one morphological type.…”

Section: Introductionmentioning

confidence: 99%

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Evolution in the H I Gas Content of Galaxy Groups: Pre-Processing and Mass Assembly in the Current Epoch

2013

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We present an analysis of the neutral hydrogen (H I) content and distribution of galaxies in groups as a function of their parent dark matter halo mass. The Arecibo Legacy Fast ALFA survey α.40 data release allows us, for the first time, to study the H I properties of over 740 galaxy groups in the volume of sky common to the Sloan Digital Sky Survey and ALFALFA surveys. We assigned ALFALFA H I detections a group membership based on an existing magnitude/volume-limited SDSS DR7 group/cluster catalog. Additionally, we assigned group "proximity" membership to H I detected objects whose optical counterpart falls below the limiting optical magnitude-thereby not contributing substantially to the estimate of the group stellar mass, but significantly to the total group H I mass. We find that only 25% of the H I detected galaxies reside in groups or clusters, in contrast to approximately half of all optically detected galaxies. Further, we plot the relative positions of optical and H I detections in groups as a function of parent dark matter halo mass to reveal strong evidence that H I is being processed in galaxies as a result of the group environment: as optical membership increases, groups become increasingly deficient of H I rich galaxies at their center and the H I distribution of galaxies in the most massive groups starts to resemble the distribution observed in comparatively more extreme cluster environments. We find that the lowest H I mass objects lose their gas first as they are processed in the group environment, and it is evident that the infall of gas rich objects is important to the continuing growth of large scale structure at the present epoch, replenishing the neutral gas supply of groups. Finally, we compare our results to those of cosmological simulations and find that current models cannot simultaneously predict the H I selected halo occupation distribution for both low and high mass halos.

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Section: Halo Occupation Distributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evolution in the H I Gas Content of Galaxy Groups: Pre-Processing and Mass Assembly in the Current Epoch

2013

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“…Image showing contours of neutral hydrogen gas with grayscale being optical observations from the Digitized Sky Survey. This is one group as determined by the FoF method but could be broken into two groups [3].…”

Section: Current Group Finding Techniquesmentioning

confidence: 99%

Using Networking Algorithms to Assess the Environment of Galaxy Groups

Bramson

Wilcots

1970

Proc. Wisc. Space Conf.

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Understanding the environment in which a galaxy resides is crucial to our understanding of galaxy evolution. Most galaxies (~70%) live in groups and it is important to develop a quantitative understanding of how galaxies are distributed within groups and how groups are distributed in the larger scale structure. In addition to the traditional friends-of-friends algorithm, I have applied various concepts from networking algorithms to understand the network of galaxy groups in clusters, and to understand the substructure within groups. Doing so provides a new method of gauging the large scale environments of galaxies and groups, and will result in a more concrete way to define a group and to quantify the strength of the community structure that exists.

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The evolution of the gas content of galaxy groups

Wilcots

2009

Astron Nachr

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The current state of our understanding of the nature of the baryon content of galaxy groups, derived largely from a large body of X-ray observations, leaves us with two key questions. First, what are the relative fractions of the hot, warm/hot, and neutral gas in galaxy groups, and how is each phase distributed within groups? Second, how has the baryon content of galaxy groups evolved over time and what is its relationship to the dynamical evolution of the group? We present the results from a number of investigations of the HI content, the properties of bent-double radio sources in groups, and deep searches for diffuse synchrotron emission in groups are now shedding light on the evolution of the baryon content of galaxy groups.From planets to dark energy: the modern radio universe

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H I Observations of Five Groups of Galaxies

Cited by 47 publications

References 46 publications

Evolution in the H I Gas Content of Galaxy Groups: Pre-Processing and Mass Assembly in the Current Epoch

Evolution in the H I Gas Content of Galaxy Groups: Pre-Processing and Mass Assembly in the Current Epoch

Using Networking Algorithms to Assess the Environment of Galaxy Groups

The evolution of the gas content of galaxy groups

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