A Dark Hydrogen Cloud in the Virgo Cluster

Minchin, R. F.; Davies, Jonathan Ivor; Disney, M. J.; Boyce, P. J.; Garcia, Diego A.; Jordan, C.; Kilborn, V. A.; Lang, R. H.; Roberts, Sarah; Sabatini, S.; Driel, W. van

doi:10.1086/429538

Cited by 96 publications

(117 citation statements)

References 32 publications

Supporting

Mentioning

112

Contrasting

Unclassified

Order By: Relevance

“…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.

View full text Add to dashboard Cite

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.

show abstract

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.

View full text Add to dashboard Cite

show abstract

“…Thus velocity spreads along tidal tails of only 200 km s −1 can be caused by collisions at speeds higher than 1000 km s −1 , contrary to what intuition may tell (Minchin et al 2007). …”

Section: The Role Of High-speed Collisionsmentioning

confidence: 67%

“…The Dark Galaxy candidate VirgoHI21. Left: The observed system as seen in HI, a combination of the data set obtained at the Westerbork SRT by Minchin et al (2007), which has high spatial resolution, and the data set obtained at Arecibo by Haynes et al (2007), which offers a better surface brightness sensitivity. VirgoHI21 is the elongated condensation at about mid-distance in the HI tail.…”

Section: A Numerical Model Of Virgohi21mentioning

confidence: 99%

Tidal Debris Posing as Dark Galaxies

2007

View full text Add to dashboard Cite

Abstract. Debris sent into the intergalactic medium during tidal collisions has received much attention as it can tell us about several fundamental properties of galaxies, in particular their missing mass, both in the form of cosmological Dark Matter and so-called Lost Baryons.High velocity encounters, which are common in clusters of galaxies, are able to produce faint tidal debris that may appear as star-less, free floating HI clouds. These may be mistaken for Dark Galaxies, a putative class of gaseous, dark matter (DM) dominated, objects which for some reason never managed to form stars. VirgoHI21, in the Virgo Cluster, is by far the most spectacular and most discussed Dark Galaxy candidate so far detected in HI surveys. We show here that it is most likely made out of material expelled 750 Myr ago from the nearby spiral galaxy NGC 4254 during its fly-by at about 1000 km s −1 by a massive intruder. Our numerical model of the collision is able to reproduce the main characteristics of the system: in particular the absence of stars, and its prominent velocity gradient. Originally attributed to the gas being in rotation within a massive dark matter halo, we find it instead to be consistent with a combination of simple streaming motion plus projection effects .Based on our multi-wavelength and numerical studies of galaxy collisions, we discuss several ways to identify a tidal origin in a Dark Galaxy candidate such as optical and millimetrewave observations to reveal a high metallicity and CO lines, and more importantly, kinematics indicating the absence of a prominent Dark Matter halo. We illustrate the method using another HI system in Virgo, VCC 2062, which is most likely a Tidal Dwarf Galaxy . Now, whereas tidal debris should not contain any dark matter from the halo of their parent galaxies, it may exhibit missing mass in the form of dark baryons, unaccounted for by classical observations, as recently found in the collisional ring of NGC 5291 and probably in the TDG VCC 2062. These "Lost Baryons" must originally have been located in the disks of their parent galaxies.

show abstract

“…A candidate "dark galaxy" was discovered and dubbed "VirgoHI21" (Minchin et al 2007 and refs therein and these proceedings). The discovery at Jodrell Bank was corroborated by Arecibo and WSRT observations.…”

Section: The Case Of Virgohi21mentioning

confidence: 99%

ALFALFA: HI Cosmology in the Local Universe

Giovanelli

2007

Proc. IAU

View full text Add to dashboard Cite

Abstract. For the last 25 years, the 21 cm line has been used productively to investigate the large-scale structure of the Universe, its peculiar velocity field and the measurement of cosmic parameters. In February 2005 a blind HI survey that will cover 7074 square degrees of the high latitude sky was started at Arecibo, using the 7-beam feed L-band feed array (ALFA). Known as the Arecibo Legacy Fast ALFA (ALFALFA) Survey, the program is producing a census of HI-bearing objects over a cosmologically significant volume of the local Universe. With respect to previous blind HI surveys, ALFALFA offers an improvement of about one order of magnitude in sensitivity, 4 times the angular resolution, 3 times the spectral resolution, and 1.6 times the total bandwidth of HIPASS. ALFALFA can detect 7 × 10 4 D 2 M of HI, where D is the source distance in Mpc. As of mid 2007, 44% of the survey observations and 15% of the source extraction are completed. We discuss the status of the survey and present a few preliminary results, in particular with reference to the proposed "dark galaxy" VirgoHI21.Keywords. galaxies: distances and redshifts, galaxies: dwarf, galaxies: evolution, galaxies: formation, galaxies: mass function, galaxies: spiral, cosmology: cosmological parameters, cosmology: observations, cosmology: large-scale structure of universe, radio lines: galaxies What is ALFALFA?Comprehensive wide angle surveys of the extragalactic HI sky became possible with the advent of multifeed front-end systems at L-band. The first such system with spectroscopic capability was installed on the 64 m Parkes telescope in Australia, and has produced the excellent results of the HIPASS survey (Barnes et al. 2001). The 1990s upgrade of the Arecibo telescope, which replaced its line feeds with a Gregorian subreflector system, made it possible for that telescope to host feed arrays, as proposed by Kildal et al. (1993). Eventually a 7-beam radio "camera", named ALFA (Arecibo Lband Feed Array), became operational at Arecibo, enabling large-scale mapping projects with the great sensitivity of the 305-m telescope. A diverse set of mapping projects are now underway at that observatory, ranging from extragalactic HI line, to Galactic line and continuum, to pulsar searches. ALFALFA, the Arecibo Legacy Fast ALFA Survey, aims to map the peri-and extragalactic HI emission over 7074 deg 2 of the high galactic latitude sky. This will require a total of 4130 hours of telescope time. Exploiting the large collecting area of the Arecibo antenna and its relatively small beam size (∼3.5 ), ALFALFA will be eight times more sensitive than HIPASS with ∼four times better angular resolution. The combination of sensitivity and angular resolution allows dramatically improved ability in determining the position of HI sources, a detail of paramount importance in the identification of source counterparts at other wavelengths. Furthermore, its spectral backend provides 3 times better spectral resolution (5.3 km s −1 at z = 0) and over 1.4 times more bandwidth. These advan...

show abstract

A Dark Hydrogen Cloud in the Virgo Cluster

Cited by 96 publications

References 32 publications

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

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

Tidal Debris Posing as Dark Galaxies

ALFALFA: HI Cosmology in the Local Universe

Contact Info

Product

Resources

About