VERTICO: The Virgo Environment Traced in CO Survey

Brown, Toby; Wilson, C. D.; Zabel, Nikki; Davis, Timothy A.; Boselli, A.; Chung, Aeree; Ellison, Sara L.; Lagos, Claudia del P.; Stevens, Adam; Cortese, Luca; Bahé, Yannick M.; Bisaria, Dhruv; Bolatto, Alberto D.; Cashmore, Claire R.; Catinella, Barbara; Chown, R.; Diemer, Benedikt; Elahi, Pascal J.; Hani, Maan H.; Jiménez-Donaire, María J.; Lee, Bumhyun; Leidig, K.; Mok, Angus; Olsen, Karen P.; Parker, Laura C.; Roberts, Ian; Smith, Rory; Spekkens, Kristine; Thorp, Mallory; Tonnesen, Stephanie; Vienneau, Evan; Villanueva, V.; Vogel, S. N.; Wadsley, James; Welker, Charlotte; Yoon, Hyein

doi:10.3847/1538-4365/ac28f5

“…HCN, HNC, and HCO + are probably even thicker. very typical for spiral galaxies (Leroy et al 2021;Brown et al 2021). Indeed, the star formation efficiency of the molecular gas in NGC 4526 is consistent with the values in many spiral galaxies even though its gas content is lower than most of theirs.…”

Section: Co Isotopologuessupporting

confidence: 60%

Down but Not Out: Properties of the Molecular Gas in the Stripped Virgo Cluster Early-type Galaxy NGC 4526

Young

¹

,

Meier

²

,

Crocker

³

et al. 2022

ApJ

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We present Atacama Large Millimeter/submillimeter Array data on the 3 mm continuum emission, CO isotopologues (12CO, 13CO, and C18O), and high-density molecular tracers (HCN, HCO+, HNC, HNCO, CS, CN, and CH3OH) in NGC 4526. These data enable a detailed study of the physical properties of the molecular gas in a longtime resident of the Virgo Cluster; comparisons to more commonly studied spiral galaxies offer intriguing hints into the processing of molecular gas in the cluster environment. Many molecular line ratios in NGC 4526, along with our inferred abundances and CO/H2 conversion factors, are similar to those found in nearby spirals. One striking exception is the very low observed 12CO/13CO(1−0) line ratio, 3.4 ± 0.3, which is unusually low for spirals though not for Virgo Cluster early-type galaxies. We carry out radiative transfer modeling of the CO isotopologues with some archival (2−1) data, and we use Bayesian analysis with Markov Chain Monte Carlo techniques to infer the physical properties of the CO-emitting gas. We find surprisingly low [12CO/13CO] abundance ratios of 7.8 − 1.5 + 2.7 and 6.5 − 1.3 + 3.0 at radii of 0.4 kpc and 1 kpc. The emission from the high-density tracers HCN, HCO+, HNC, CS, and CN is also relatively bright, and CN is unusually optically thick in the inner parts of NGC 4526. These features hint that processing in the cluster environment may have removed much of the galaxy’s relatively diffuse, optically thinner molecular gas along with its atomic gas. Angular momentum transfer to the surrounding intracluster medium may also have caused contraction of the disk, magnifying radial gradients such as we find in [13CO/C18O]. More detailed chemical evolution modeling would be interesting in order to explore whether the unusual [12CO/13CO] abundance ratio is entirely an environmental effect or whether it also reflects the relatively old stellar population in this early-type galaxy.

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“…NGC 4419 is in fairly close proximity to both BCs and based on its estimated stellar mass and metallicity, it is likely a close match for the metallicity of these BCs. In addition, there is strong evidence in both H I (Chung et al 2009) and CO (Brown et al 2021) that this galaxy is being ram pressure stripped. However, as ram pressure tails only extend in one general direction (in the wake of a galaxy's motion through the ICM) and BC4 is to the south of NGC 4419 and BC5 is to the north, it is extremely unlikely that this is the point of origin of these BCs.…”

Section: Search For Points Of Originmentioning

confidence: 96%

“…Thus, BC1 would have needed a large ejection velocity (>500 km s −1 in total) for NGC 4579 to be its parent object. Furthermore, other than a slightly H I-deficient disk, 26 NGC 4579 shows little sign of recent disturbance in either its H I or CO morphology and kinematics (Chung et al 2009;Brown et al 2021) ). Thus, NGC 4579 does not seem to be a viable candidate point of origin for BC1, and the genuine point of origin must presumably be beyond the region shown in Figure 12 ( > 280 kpc away), but we are unable to identify any strong candidates this far away.…”

Section: Search For Points Of Originmentioning

confidence: 98%

Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. II. A New Class of Stellar System

Jones

¹

,

Sand

²

,

Bellazzini³

et al. 2022

ApJ

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We discuss five blue stellar systems in the direction of the Virgo cluster, analogous to the enigmatic object SECCO 1 (AGC 226067). These objects were identified based on their optical and UV morphology and followed up with H i observations with the Very Large Array (and Green Bank Telescope), Multi Unit Spectroscopic Explorer (on the Very Large Telescope) optical spectroscopy, and Hubble Space Telescope imaging. These new data indicate that one system is a distant group of galaxies. The remaining four are extremely low mass (M * ∼ 105 M ⊙), are dominated by young blue stars, have highly irregular and clumpy morphologies, are only a few kiloparsecs across, yet host an abundance of metal-rich, 12 + log ( O / H ) > 8.2 , H ii regions. These high metallicities indicate that these stellar systems formed from gas stripped from much more massive galaxies. Despite the young age of their stellar populations, only one system is detected in H i, while the remaining three have minimal (if any) gas reservoirs. Furthermore, two systems are surprisingly isolated and have no plausible parent galaxy within ∼30′ (∼140 kpc). Although tidal stripping cannot be conclusively excluded as the formation mechanism of these objects, ram pressure stripping more naturally explains their properties, in particular their isolation, owing to the higher velocities, relative to the parent system, that can be achieved. Therefore, we posit that most of these systems formed from ram-pressure-stripped gas removed from new infalling cluster members and survived in the intracluster medium long enough to become separated from their parent galaxies by hundreds of kiloparsecs and that they thus represent a new type of stellar system.

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“…For example, molecular gas discs in cluster galaxies have been found to be truncated and/or morphologically and kinematically disturbed, while molecular gas fractions have been found to be deficient compared to field galaxies at fixed stellar mass (e.g. Vollmer et al 2008;Fumagalli et al 2009;Boselli et al 2014a;Lee et al 2017;Lee & Chung 2018;Zabel et al 2019;Cramer et al 2021;Brown et al 2021). Additionally, molecular gas fractions can also be enhanced in cluster galaxies, as a result of ram pressure, which can facilitate the conversion of atomic into molecular gas (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This work is one of the early science papers of the Atacama Large Millimeter/submillimeter Array (ALMA) large programme the "Virgo Environment Traced in CO" (VERTICO, Brown et al 2021, hereafter referred to as B21). VERTICO comprises homogeneous CO(2-1) observations of 51 spiral galaxies in the Virgo cluster (of which 49 are detected), and is designed to systematically study the physical mechanisms that drive galaxy evolution in dense environments.…”

Section: Introductionmentioning

confidence: 99%

VERTICO II: effects of HI-identified environmental mechanisms on molecular gas

Zabel¹,

Brown²,

Wilson³

et al. 2022

Preprint

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In this VERTICO early science paper we explore in detail how environmental mechanisms, identified in Hi, affect the resolved properties of molecular gas reservoirs in cluster galaxies. The molecular gas is probed using ALMA ACA (+TP) observations of 12 CO(2-1) in 51 spiral galaxies in the Virgo cluster (of which 49 are detected), all of which are included in the VIVA Hi survey. The sample spans a stellar mass range of 9 ≤ log M /M ≤ 11. We study molecular gas radial profiles, isodensity radii, and surface densities as a function of galaxy Hi deficiency and morphology. There is a weak correlation between global Hi and H 2 deficiencies, and resolved properties of molecular gas correlate with Hi deficiency: galaxies that have large Hi deficiencies have relatively steep and truncated molecular gas radial profiles, which is due to the removal of low-surface density molecular gas on the outskirts. Therefore, while the environmental mechanisms observed in Hi also affect molecular gas reservoirs, there is only a moderate reduction of the total amount of molecular gas.

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VERTICO: The Virgo Environment Traced in CO Survey

Cited by 31 publications

References 158 publications

Down but Not Out: Properties of the Molecular Gas in the Stripped Virgo Cluster Early-type Galaxy NGC 4526

Down but Not Out: Properties of the Molecular Gas in the Stripped Virgo Cluster Early-type Galaxy NGC 4526

Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. II. A New Class of Stellar System

VERTICO II: effects of HI-identified environmental mechanisms on molecular gas

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