The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey

Bellazzini, M.; Beccari, G.; Battaglia, G.; Martín, Nicolás F.; Testa, V.; Ibata, Rodrigo; Correnti, Matteo; Cusano, F.; Sani, E.

doi:10.1051/0004-6361/201425262

Cited by 18 publications

(32 citation statements)

References 52 publications

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“…Our detection for AGC 258242 would be well outside that footprint, assuming the LBT image is centered on the Hi centroid. In the case of AGC 268074, the object detected in our pODI images would likely fall within the LBT image footprint, but Bellazzini et al (2015) do not detect an overdensity in their data for this UCHVC.…”

Section: Overdensities With 90% < ξ < 97%mentioning

confidence: 67%

“…While they do not meet the criteria for robust detections because of their lack of supporting overdensities, these marginal detections are still potential stellar counterparts. Two of these objects were observed by Bellazzini et al (2015), AGC 258242 and AGC 268074. Neither of these objects had significant stellar overdensities in the Large Binocular Telescope images from that work, though the footprint of those images is smaller (14 × 7 ) than that of the pODI images.…”

Section: Overdensities With 90% < ξ < 97%mentioning

confidence: 99%

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Five Gas-rich Ultrafaint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources

Janesh

Rhode

Salzer

et al. 2019

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We present results from the analysis of WIYN pODI imaging of 23 ultra-compact high-velocity clouds (UCHVCs), which were identified in the ALFALFA Hi survey as possible dwarf galaxies in or near the Local Group. To search for a resolved stellar population associated with the Hi gas in these objects, we carried out a series of steps designed to identify stellar overdensities in our optical images. We identify five objects that are likely stellar counterparts to the UCHVCs, at distances of ∼350 kpc to ∼1.6 Mpc. Two of the counterparts were already described in Janesh et al. (2015) and Janesh et al. (2017); the estimated distance and detection significance for one of them changed in the final analysis of the full pODI data set. At their estimated distances, the detected objects have Hi masses from 2 × 10 4 −3 × 10 6 M , M V from −1.4−−7.1, and stellar masses from 4 × 10 2 −4 × 10 5 M . None of the objects shows evidence of a young stellar population. Their properties would make the UCHVCs some of the most extreme objects in and around the Local Group, comparable to ultra faint dwarf galaxies in their stellar populations, but with significant gas content. Such objects probe the extreme end of the galaxy mass function, and provide a testbed for theories regarding the baryonic feedback processes that impact star formation and galaxy evolution in this low-mass regime.

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Section: Overdensities With 90% < ξ < 97%mentioning

confidence: 67%

Section: Overdensities With 90% < ξ < 97%mentioning

confidence: 99%

Five Gas-rich Ultrafaint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources

Janesh

Rhode

Salzer

et al. 2019

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“…8. The source (ID number 100038 in our catalog) is seen as extended both in the OSIRIS images and in the deep g,r images of the original SECCO survey (Bellazzini et al 2015a). It has a nearby point-like companion (100046) with significant Hα excess.…”

Section: Hα Imaging: Searching For Additional Piecesmentioning

confidence: 99%

Alone on a wide wide sea. The origin of SECCO 1, an isolated star-forming gas cloud in the Virgo cluster*†‡

Bellazzini¹,

Armillotta

Perina

et al. 2018

Monthly Notices of the Royal Astronomical Society

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SECCO 1 is an extremely dark, low-mass (M 10 5 M ), star-forming stellar system lying in the Low Velocity Cloud (LVC) substructure of the Virgo cluster of galaxies, and hosting several Hii regions. Here we review our knowledge of this remarkable system, and present the results of (a) additional analysis of our panoramic spectroscopic observations with MUSE, (b) the combined analysis of Hubble Space Telescope and MUSE data, and (c) new narrow-band observations obtained with OSIRIS@GTC to search for additional Hii regions in the surroundings of the system. We provide new evidence supporting an age as young as < ∼ 4 Myr for the stars that are currently ionising the gas in SECCO 1. We identify only one new promising candidate Hii region possibly associated with SECCO 1, thus confirming the extreme isolation of the system. We also identify three additional candidate pressure-supported dark clouds in Virgo among the targets of the SECCO survey. Various possible hypotheses for the nature and origin of SECCO 1 are considered and discussed, also with the help of dedicated hydrodynamical simulations showing that a hydrogen cloud with the characteristics of SECCO 1 can likely survive for > ∼ 1 Gyr while traveling within the LVC Intra Cluster Medium.

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“…Previous work has shown that stellar counterparts for UCHVCs appear to be rare and correspond to more distant, massive systems with typical H i masses of ∼ 10 7 M (Bellazzini et al 2015;Sand et al 2015). However, Janesh et al (2015) identified a tentative optical counterpart for one UCHVC, AGC 198606, at a distance of 383 kpc.…”

Section: Introductionmentioning

confidence: 95%

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 StEllar Counterparts of COmpact high velocity clouds (SECCO) survey

Cited by 18 publications

References 52 publications

Five Gas-rich Ultrafaint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources

Five Gas-rich Ultrafaint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources

Alone on a wide wide sea. The origin of SECCO 1, an isolated star-forming gas cloud in the Virgo cluster*†‡

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

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