Faint and Fading Tails: The Fate of Stripped H i Gas in Virgo Cluster Galaxies

Abstract

Although many galaxies in the Virgo cluster are known to have lost significant amounts of Hi gas, only about a dozen features are known where the Hi extends significantly outside its parent galaxy. Previous numerical simulations have predicted that Hi removed by ram pressure stripping should have column densities far in excess of the sensitivity limits of observational surveys. We construct a simple model to try and quantify how many streams we might expect to detect. This accounts for the expected random orientation of the streams in position and velocity space as well as the expected stream length and mass of stripped Hi. Using archival data from the Arecibo Galaxy Environment Survey, we search for any streams which might previously have been missed in earlier analyses. We report the confident detection of ten streams as well as sixteen other less sure detections. We show that these well-match our analytic predictions for which galaxies should be actively losing gas, however the mass of the streams is typically far below the amount of missing Hi in their parent galaxies, implying that a phase change and/or dispersal renders the gas undetectable. By estimating the orbital timescales we estimate that dissolution rates of 1-10 M ⊙ yr −1 are able to explain both the presence of a few long, massive streams and the greater number of shorter, less massive features.

Deep optical imaging of the dark galaxy candidate AGESVC1 282

“…Several candidate parent galaxies are visible, though (arguably) none are particularly convincing. The two most promising are VCC 740 and VCC 713 (see Taylor et al 2020 for full details). VCC 740 shows a hint of an extension toward AGESVC1 282 and it is at a similar radial velocity (66 km s −1 difference), though the extension is only barely visible in one channel.…”

The Widefield Arecibo Virgo Extragalactic Survey: Early Results on Known Dark Sources

“…AGES discovered a large number of optically-dark H i clouds, including some with anomalously high velocity widths that could not be easily explained as products of harassment (Taylor et al 2012(Taylor et al , 2017. The AGES data also demonstrated that deep surveys with good sensitivity to low column-density gas could detect previously undiscovered ram pressure stripped H i tails: ten new tails were confidently detected, almost doubling the number of known tails in the cluster, along with sixteen possible detections (Taylor et al 2020).…”

A Dynamical Mass Estimate from the Magellanic Stream

“…In principle, a similar mass estimator could be used to estimate the mass of other systems with observable streams, such as galaxy clusters with visible HI streams. A prime candidate for such an analysis is the Virgo cluster, which contains a large number of observed streams (Taylor et al 2020).…”

“…Given the observed stream lengths in the Virgo cluster, if we use Equation 1, we would obtain a mass on the order of 10 12 𝑀 , which is an unrealistically low estimate for the Virgo cluster (or a typical galaxy cluster). The longest stream observed in the Virgo cluster has a length of 500 kpc (Taylor et al 2020), with many shorter streams with lengths under 30 kpc. The most likely explanation for this phenomenon is that the typical galaxies orbiting in Virgo experience very different ram pressure stripping timescales than what we see in the MW.…”