THE GALFA-H i COMPACT CLOUD CATALOG

Saul, Destry; Peek, J. E. G.; Grcevich, Jana; Putman, Mary E.; Douglas, K. A.; Korpela, E. J.; Stanimirović, Snežana; Heiles, Carl; Gibson, Steven J.; Lee, Min Young; Begum, Ayesha; Brown, Alexander; Burkhart, Blakesley; Hamden, Erika; Pingel, N. M.; Tonnesen, Stephanie

doi:10.1088/0004-637x/758/1/44

Cited by 64 publications

(92 citation statements)

References 52 publications

(74 reference statements)

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“…1 (Bellazzini et al 2015a, B15a, hereafter) is a survey aimed at searching for stellar counterparts of Ultra Compact High Velocity Clouds (UCHVC) of neutral hydrogen that have been recently proposed by different teams as candidate mini-halos residing in the Local Group or its surroundings (D < ∼ 3.0 Mpc; Adams et al 2013;Saul et al 2012, ALFALFA and GALFA-Hi surveys, respectively). The only way to confirm the nature of UCHVCs as small gas-rich dwarf galaxies is to identify a concomitant stellar population that can allow to constrain the distance to the system.…”

Section: Seccomentioning

confidence: 99%

A very dark stellar system lost in Virgo: kinematics and metallicity of SECCO 1 with MUSE

Beccari

Bellazzini

Magrini

et al. 2016

Mon. Not. R. Astron. Soc.

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We present the results of VLT-MUSE integral field spectroscopy of SECCO 1, a faint, star-forming stellar system recently discovered as the stellar counterpart of an Ultra Compact High Velocity Cloud (HVC274.68+74.0), very likely residing within a substructure of the Virgo cluster of galaxies. We have obtained the radial velocity of a total of 38 individual compact sources identified as Hii regions in the main and secondary body of the system, and derived the metallicity for 18 of them. We provide the first direct demonstration that the two stellar bodies of SECCO 1 are physically associated and that their velocities match the Hi velocities. The metallicity is quite uniform over the whole system, with a dispersion lower than the uncertainty on individual metallicity estimates. The mean abundance, 12 + log(O/H) = 8.44, is much higher than the typical values for local dwarf galaxies of similar stellar mass. This strongly suggests that the SECCO 1 stars were born from a pre-enriched gas cloud, possibly stripped from a larger galaxy. Using archival HST images we derive a total stellar mass of 1.6 × 10 5 M for SECCO 1, confirming that it has a very high Hi to stellar mass ratio for a dwarf galaxy, M Hi /M * ∼ 100. The star formation rate, derived from the H α flux is a factor of more than 10 higher than in typical dwarf galaxies of similar luminosity.

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Section: Seccomentioning

confidence: 99%

A very dark stellar system lost in Virgo: kinematics and metallicity of SECCO 1 with MUSE

Beccari

Bellazzini

Magrini

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Most recently, so-called ultra-compact high velocity clouds (UCHVCs) of neutral hydrogen have been identified by the Galactic Arecibo L-Band Feed Array H I (GALFA-H I) and Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) surveys (Saul et al 2012;Adams et al 2013, respectively) as potential sites of gas-bearing dark matter halos. Because the spatial distribution and physical properties of these UCHVCs are consistent with some being faint dwarf galaxies in the Local Volume (e.g., Giovanelli et al 2010;Adams et al 2013), several searches have been undertaken to characterize their optical properties (Bellazzini et al 2015a;Sand et al 2015;Tollerud et al 2015;Janesh et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Hubble Space Telescope Imaging of the Ultra-compact High Velocity Cloud AGC 226067: A Stripped Remnant in the Virgo Cluster

Sand

Seth

Crnojević

et al. 2017

ApJ

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We analyze the optical counterpart to the ultra-compact high velocity cloud AGC226067, utilizing imaging taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The color-magnitude diagram of the main body of AGC226067 reveals an exclusively young stellar population, with an age of ∼7-50 Myr, and is consistent with a metallicity of [Fe/H]∼−0.3 as previous work has measured via H II region spectroscopy. Additionally, the color-magnitude diagram is consistent with a distance of D≈17 Mpc, suggesting an association with the Virgo cluster. A secondary stellar system located ∼1 6 (∼8 kpc) away in projection has a similar stellar population. The lack of an old red giant branch (5 Gyr) is contrasted with a serendipitously discovered Virgo dwarf in the ACS field of view (Dw J122147+132853), and the total diffuse light from AGC226067 is consistent with the luminosity function of the resolved ∼7-50 Myr stellar population. The main body of AGC226067 has a M V =−11.3±0.3, or M stars =5.4±1.3×104 M e given the stellar population. We searched 20 deg 2 of imaging data adjacent to AGC226067 in the Virgo Cluster, and found two similar stellar systems dominated by a blue stellar population, far from any massive galaxy counterpart-if this population has star-formation properties that are similar to those ofAGC226067, it implies ∼0.1 M e yr −1 in Virgo intracluster star formation. Given its unusual stellar population, AGC226067 is likely a stripped remnant and is plausibly the result of compressed gas from the ram pressure stripped M86 subgroup (∼350 kpc away in projection) as it falls into the Virgo Cluster.

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“…Adams et al (2013, hereafter A13) built on this work, presenting a catalog of sources with specific selection criteria for the 40% complete ALFALFA survey. Similarly, Saul et al (2012) presented a catalog of compact H i clouds from GALFA H i survey, highlighting those that were potentially good galaxy candidates. These catalogs represent an excellent starting point for identifying potential gas-bearing dark matter halos in the local universe, and theoretical models suggest they contain good candidates (e.g., Faerman et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Identifying galaxy candidates in WSRT H i imaging of ultra-compact high velocity clouds

Adams

Oosterloo

Cannon

et al. 2016

A&A

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Ultra-compact high velocity clouds (UCHVCs) were identified in the Arecibo Legacy Fast ALFA (ALFALFA) H i survey as potential gas-bearing dark matter halos. Here we present higher resolution neutral hydrogen (H i) observations of twelve UCHVCS with the Westerbork Synthesis Radio Telescope (WSRT). The UCHVCs were selected based on a combination of size, isolation, large recessional velocity and high column density as the best candidate dark matter halos. The WSRT data were tapered to image the UCHVCs at 210 (comparable to the Arecibo resolution) and 105 angular resolution. In a comparison of the single-dish to interferometer data, we find that the integrated line flux recovered in the WSRT observations is generally comparable to that from the single-dish ALFALFA data. In addition, any structure seen in the ALFALFA data is reproduced in the WSRT maps at the same angular resolution. At 210 resolution all the sources are generally compact with a smooth H i morphology, as expected from their identification as UCHVCs. At the higher angular resolution, a majority of the sources break into small clumps contained in a diffuse envelope. These UCHVCs also have no ordered velocity motion and are most likely Galactic halo clouds. We identify two UCHVCs, AGC 198606 and AGC 249525, as excellent galaxy candidates based on maintaining a smooth H i morphology at higher angular resolution and showing ordered velocity motion consistent with rotation. A third source, AGC 249565, lies between these two populations in properties and is a possible galaxy candidate. If interpreted as gas-bearing dark matter halos, the three candidate galaxies have rotation velocities of 8 − 15 km s −1 , H i masses of 0.6 − 50 × 10 5 M , H i radii of 0.3 − 2 kpc, and dynamical masses of 2 − 20 × 10 7 M for a range of plausible distances. These are the UCHVCs with the highest column density values in the ALFALFA H i data and we suggest this is the best way to identify further candidates.

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THE GALFA-H i COMPACT CLOUD CATALOG

Cited by 64 publications

References 52 publications

A very dark stellar system lost in Virgo: kinematics and metallicity of SECCO 1 with MUSE

A very dark stellar system lost in Virgo: kinematics and metallicity of SECCO 1 with MUSE

Hubble Space Telescope Imaging of the Ultra-compact High Velocity Cloud AGC 226067: A Stripped Remnant in the Virgo Cluster

Identifying galaxy candidates in WSRT H i imaging of ultra-compact high velocity clouds

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