A 500 kpc H
                    <scp>i</scp>
                    Extension of the Virgo Pair NGC 4532/DDO 137 Detected by the Arecibo Legacy Fast ALFA (ALFALFA) Survey

Koopmann, Rebecca A.; Giovanelli, Riccardo; Haynes, Martha P.; Kent, Brian R.; Balonek, T. J.; Brosch, Noah; Higdon, James L.; Salzer, John J.; Spector, O.

doi:10.1086/591124

Cited by 44 publications

(50 citation statements)

References 36 publications

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“…Rather, these results are consistent with the observation that most long streams in Virgo are not associated with highly deficient galaxies (e.g. Koopmann et al 2008, Minchin et al 2007, and those which are have masses insufficient to explain the presumed parent galaxy's strong deficiency (Oosterloo et al 2005).…”

Section: Global Propertiessupporting

confidence: 86%

Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris?

Taylor

Davies

Jáchym

et al. 2017

Mon. Not. R. Astron. Soc.

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Isolated Hi clouds with no optical counterparts are often taken as evidence for galaxygalaxy interactions, though an alternative hypothesis is that these are primordial 'dark galaxies' which have not formed stars. Similarly, certain kinematic features in Hi streams are also controversial, sometimes taken as evidence of dark galaxies but also perhaps explicable as the result of harassment. We numerically model the passage of a galaxy through the gravitational field of cluster. The galaxy consists of SPH particles for the gas and n-bodies for the stars and dark matter, while the cluster includes the gravitational effects of substructure using 400 subhalos (the effects of the intracluster medium are ignored). We find that harassment can indeed produce long Hi streams and these streams can include kinematic features resembling dark galaxy candidates such as VIRGOHI21. We also show that apparent clouds with diameter <20 kpc and velocity widths <50 km s −1 are almost invariably produced in these simulations, making tidal debris a highly probable explanation. In contrast, we show that the frequency of isolated clouds of the same size but velocity width >100 km s −1 is negligible -making this a very unlikely explanation for the observed clouds in the Virgo cluster with these properties.

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Section: Global Propertiessupporting

confidence: 86%

Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris?

Taylor

Davies

Jáchym

et al. 2017

Mon. Not. R. Astron. Soc.

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“…Notice that HI clouds without optical counterparts have been found in Davies et al (2004); Minchin et al (2005); Kent et al (2007); Koopmann et al (2008); Taylor et al (2012Taylor et al ( , 2013; Janowiecki et al (2015). We plan to address this in a future paper.…”

Section: Summary and Discussionmentioning

confidence: 93%

Neutral hydrogen in galaxy clusters: impact of AGN feedback and implications for intensity mapping

Villaescusa-Navarro¹,

Planelles²,

Borgani³

et al. 2016

Mon. Not. R. Astron. Soc.

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By means of zoom-in hydrodynamic simulations we quantify the amount of neutral hydrogen (HI) hosted by groups and clusters of galaxies. Our simulations, which are based on an improved formulation of smoothed particle hydrodynamics (SPH), include radiative cooling, star formation, metal enrichment and supernova feedback, and can be split in two different groups, depending on whether feedback from active galactic nuclei (AGN) is turned on or off. Simulations are analyzed to account for HI self-shielding and the presence of molecular hydrogen. We find that the mass in neutral hydrogen of dark matter halos monotonically increases with the halo mass and can be well described by a power-law of the form M HI (M, z) ∝ M 3/4 . Our results point out that AGN feedback reduces both the total halo mass and its HI mass, although it is more efficient in removing HI. We conclude that AGN feedback reduces the neutral hydrogen mass of a given halo by ∼ 50%, with a weak dependence on halo mass and redshift. The spatial distribution of neutral hydrogen within halos is also affected by AGN feedback, whose effect is to decrease the fraction of HI that resides in the halo inner regions. By extrapolating our results to halos not resolved in our simulations we derive astrophysical implications from the measurements of Ω HI (z): halos with circular velocities larger than ∼ 25 km/s are needed to host HI in order to reproduce observations. We find that only the model with AGN feedback is capable of reproducing the value of Ω HI b HI derived from available 21cm intensity mapping observations.

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“…NGC 4532 shares a common Hi distribution with DDO 137 (Koopmann et al 2008). In addition, a ∼500 kpc Hi extension was discovered by Koopmann et al (2008) southwest of the galaxy pair. In particular, an Hi filament is running in projection across NGC 4532 in east-west direction.…”

Section: Ngc 4532mentioning

confidence: 87%

Large-scale radio continuum properties of 19 Virgo cluster galaxies

Vollmer

Soida

Beck

et al. 2013

A&A

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Deep scaled array VLA 20 and 6 cm observations including polarization of 19 Virgo spiral galaxies are presented extending previous work on the influence of the cluster environment on the radio continuum properties of Virgo cluster spiral galaxies. This sample contains six galaxies with a global minimum of 20 cm polarized emission at the receding side of the galactic disk and quadrupolar type large-scale magnetic fields. In the new sample no additional case of a ram-pressure stripped spiral galaxy with an asymmetric ridge of polarized radio continuum emission was found. In the absence of a close companion, a truncated Hi disk, together with a ridge of polarized radio continuum emission at the outer edge of the Hi disk, is a signpost of ram pressure stripping. Six out of the 19 observed galaxies (NGC 4294, NGC 4298, NGC 4457, NGC 4532, NGC 4568, NGC 4808) display asymmetric 6 cm polarized emission distributions. Three galaxies belong to tidally interacting pairs (NGC 4294, NGC 4298, NGC 4568), two galaxies host huge accreting Hi envelopes (NGC 4532, NGC 4808), and one galaxy (NGC 4457) had a recent minor merger. Tidal interactions and accreting gas envelopes can lead to compression and shear motions which enhance the polarized radio continuum emission. The resulting asymmetries are located within the Hi distribution. The 6 cm average degree of polarization only correlates with the galaxy mass or rotation velocity. In addition, galaxies with low average star formation rate per unit area have a low average degree of polarization. Shear or compression motions can enhance the degree of polarization. The average degree of polarization of tidally interacting galaxies is generally lower than expected for a given rotation velocity and star formation activity. This low average degree of polarization is at least partly due to the absence of polarized emission from the thin disk. Ram pressure stripping can decrease whereas tidal interactions most frequently decreases the average degree of polarization of Virgo cluster spiral galaxies. We found that moderate active ram pressure stripping has no influence on the spectral index, but enhances the global radio continuum emission with respect to the FIR emission, while an accreting gas envelope can but not necessarily enhances the radio continuum emission with respect to the FIR emission.

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A 500 kpc H i Extension of the Virgo Pair NGC 4532/DDO 137 Detected by the Arecibo Legacy Fast ALFA (ALFALFA) Survey

Cited by 44 publications

References 36 publications

Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris?

Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris?

Neutral hydrogen in galaxy clusters: impact of AGN feedback and implications for intensity mapping

Large-scale radio continuum properties of 19 Virgo cluster galaxies

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