The Bluedisks project, a study of unusually H i-rich galaxies – I. H i sizes and morphology

Wang, Jing; Kauffmann, Guinevere; Józsa, G. I. G.; Serra, P.; Hulst, J. M. van der; Bigiel, Frank; Brinchmann, Jarle; Verheijen, Marc; Oosterloo, Tom; Wang, Enci; Li, Cheng; Heijer, Milan den; Kerp, J.

doi:10.1093/mnras/stt722

Cited by 96 publications

(88 citation statements)

References 58 publications

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“…They ascribe the smaller HI disks to ram-pressure stripping and other types of interactions because most of the galaxies with R HI < R opt show signs of interactions. Our results here are consistent with that found in Wang et al (2013) for a sample of HI-rich galaxies, though their sample includes some galaxies with lower stellar masses and lower HI masses.…”

Section: Hi Radii and Massessupporting

confidence: 92%

“…In Section 3.4.3 we estimate the SFR and HI surface densities of GASS galaxies by assuming that the star formation is contained within R 90 and that half of the total HI is contained within R 90 . The latter is consistent with Wang et al (2013), who show that the radius enclosing half of the HI flux (their R50) for normal galaxies is comparable to or less than the optical radius (half of D 25 ).…”

Section: Derived Quantitiessupporting

confidence: 91%

“…The Bluedisks project, as described in Wang et al (2013) uses HI maps to understand the origin of the excess HI in galaxies that have high HI gas fractions compared to their predicted gas fractions. Their goal contrasts slightly with our goal, which is to understand why some galaxies with large HI reservoirs do not have high sSFRs.…”

Section: Hi Imaging Of Low-star-formingmentioning

confidence: 99%

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Resolved H I Imaging of a Population of Massive H I-Rich Galaxies With Suppressed Star Formation

Lemonias

Schiminovich

Catinella

et al. 2014

ApJ

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Despite the existence of well-defined relationships between cold gas and star formation, there is evidence that some galaxies contain large amounts of HI that do not form stars efficiently. By systematically assessing the link between HI and star formation within a sample of galaxies with extremely high HI masses (log M HI /M ⊙ > 10), we uncover a population of galaxies with an unexpected combination of high HI masses and low specific star formation rates that exists primarily at stellar masses greater than log M * /M ⊙ ∼ 10.5. We obtained HI maps of 20 galaxies in this population to understand the distribution of the HI and the physical conditions in the galaxies that could be suppressing star formation in the presence of large quantities of HI. We find that all of the galaxies we observed have low HI surface densities in the range in which inefficient star formation is common. The low HI surface densities are likely the main cause of the low sSFRs, but there is also some evidence that AGN or bulges contribute to the suppression of star formation. The sample's agreement with the global star formation law highlights its usefulness as a tool for understanding galaxies that do not always follow expected relationships. Subject headings: galaxies: formation -galaxies: evolution 1. INTRODUCTION Many theories of galaxy evolution assume that a galaxy's evolutionary stage and its cold gas content are tightly linked. For example, it is often assumed that a depleted cold gas reservoir can explain why massive galaxies are redder and exhibit less active star formation, but recent observations have challenged this picture by identifying populations of galaxies that contain significant amounts of cold gas despite their low or moderate star formation rates (Morganti et al. 2006;Serra et al. 2012;Young et al. 2013). Some attempts have been made to systematically search for these galaxies to understand them as a population. In this paper we pursue this line of reasoning by studying a sample of massive galaxies with an unusual combination of high HI masses and low specific star formation rates.Galaxies that have more cold gas than expected can be placed into two broad categories: red, early-type galaxies with unexpected measurable HI and galaxies that have significantly more HI than their star formation rates (SFRs) would suggest. In the first category, early-type galaxies were expected to be devoid of cold gas because they lack the spiral arms that indicate recent star formation. The first systematic imaging search for HI in early-type galaxies, motivated in part by the evidence for HI in individual early-types, found that HI is common at low levels in early-type galaxies in the field and could play an important role in their evolution (Morganti et al.

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Section: Hi Radii and Massessupporting

confidence: 92%

Section: Derived Quantitiessupporting

confidence: 91%

Section: Hi Imaging Of Low-star-formingmentioning

confidence: 99%

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Resolved H I Imaging of a Population of Massive H I-Rich Galaxies With Suppressed Star Formation

Lemonias

Schiminovich

Catinella

et al. 2014

ApJ

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“…Additionally, Figure 6 demonstrates that the codirectional mass fraction of cold gas in the halo stayed consistently high over cosmic time (at least until z=1). We speculate that it may be possible that this high angular momentum accretion helps to explain observations of extended XUV disks (e.g., Thilker et al 2005Thilker et al , 2007Lemonias et al 2011;Holwerda et al 2012), local extended H I disks (e.g., García-Ruiz et al 2002;Oosterloo et al 2007;Christlein & Zaritsky 2008;Sancisi et al 2008;Walter et al 2008;Wang et al 2013;Huang et al 2014;Courtois et al 2015), and corotating cold halo gas around local Milky Way analogs (e.g., Diamond-Stanic et al 2016).…”

Section: Discussionmentioning

confidence: 87%

High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

Stewart

Maller

Oñorbe

et al. 2017

ApJ

110

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We investigate angular momentum acquisition in Milky Way-sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy's halo. In all simulations, cold filamentary gas accretion to the halo results in ∼4 times more specific angular momentum in cold halo gas (λ cold 0.1) than in the dark matter halo. At z>1, this inflow takes the form of inspiraling cold streams that are co-directional in the halo of the galaxy and are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the qualitative agreement among disparate simulations, we conclude that the buildup of high angular momentum halo gas and the presence of these inspiraling cold streams are robust predictions of Lambda Cold Dark Matter galaxy formation, though the detailed morphology of these streams is significantly less certain. A growing body of observational evidence suggests that this process is borne out in the real universe.

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“…In this paper, we report a galaxy (NGC 6145) from the "Bluedisk" project (Wang et al 2013, which hosts a one-sided HI filament of 150 kpc length in pro-jected image. The Bluedisk project has mapped the HI emission of a sample of 23 galaxies with unusually high HI mass fractions, as well as a similar-sized sample of control galaxies (Wang et al 2013).…”

mentioning

confidence: 99%

The Peculiar Filamentary H i Structure of NGC 6145

Wang

Kong

et al. 2017

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In this paper, we report the peculiar HI morphology of the cluster spiral galaxy NGC 6145, which has a 150 kpc HI filament on one side that is nearly parallel to its major axis. This filament is made up of several HI clouds and the diffuse HI gas between them, with no optical counterparts. We compare its HI distribution with other one-sided HI distributions in the literature, and find that the overall HI distribution is very different from the typical tidal and ram-pressure stripped HI shape, and its morphology is inconsistent with being a pure accretion event. Only ∼30% of the total HI gas is anchored on the stellar disk, while most of HI gas forms the filament in the west. At a projected distance of 122 kpc, we find a massive elliptical companion (NGC 6146) with extended radio emission, whose axis points to an HI gap in NGC 6145. The velocity of the HI filament shows an overall light-ofsight motion of 80 to 180 km s −1 with respect to NGC 6145. Using the long-slit spectra of NGC 6145 along its major stellar axis, we find that some outer regions show enhanced star formation, while in contrast, almost no star formation activities are found in its center (<2 kpc). Pure accretion, tidal or ram-pressure stripping is not likely to produce the observed HI filament. An alternative explanation is the jet-stripping from NGC 6146, although direct evidence for a jet-cold gas interaction has not been found.

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The Bluedisks project, a study of unusually H i-rich galaxies – I. H i sizes and morphology

Cited by 96 publications

References 58 publications

Resolved H I Imaging of a Population of Massive H I-Rich Galaxies With Suppressed Star Formation

Resolved H I Imaging of a Population of Massive H I-Rich Galaxies With Suppressed Star Formation

High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

The Peculiar Filamentary H i Structure of NGC 6145

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