Hoag’s Object: evidence for cold accretion on to an elliptical galaxy

Finkelman, Ido; Моисеев, А. В.; Brosch, Noah; Katkov, Ivan

doi:10.1111/j.1365-2966.2011.19601.x

Cited by 32 publications

(31 citation statements)

References 107 publications

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“…In S0s gradual accretion could lead to SF in the existing stellar disk, perhaps in its outskirts. On the other hand, the IGM accretion onto ellipticals may result in a detached rotating ring, as in the case of Hoag's galaxy (Schweizer et al 1987;Finkelman et al 2011), without any gas cooling onto the spheroid itself.…”

Section: Fading Of the Original Sfmentioning

confidence: 99%

“…Curiously, we find only two such cases in the literature. One is Hoag's galaxy (type E0) with its detached star-forming ring for which Finkelman et al (2011) recently argued for a formation through cold accretion. Another is an H i-rich NGC 5173 (type E1) with clumpy SF regions ∼4-10 kpc from the center, possibly resulting from a merger (Vader & Vigroux 1991).…”

Section: Is Extended Sf In Etgs An S0 Phenomenon?mentioning

confidence: 99%

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GALAXY-SCALE STAR FORMATION ON THE RED SEQUENCE: THE CONTINUED GROWTH OF S0s AND THE QUIESCENCE OF ELLIPTICALS

Salim¹,

Fang²,

Rich³

et al. 2012

ApJ

100

112

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This paper examines star formation (SF) in relatively massive, primarily early-type galaxies (ETGs) at z ∼ 0.1. A sample is drawn from bulge-dominated Galaxy Evolution Explorer/Sloan Digital Sky Survey (GALEX/SDSS) galaxies on the optical red sequence with strong UV excess and yet quiescent SDSS spectra. High-resolution far-UV imaging of 27 such ETGs using Hubble Space Telescope Advanced Camera for Surveys/Solar Blind Channel (ACS/SBC) reveals structured UV morphology in 93% of the sample, consistent with low-level ongoing SF (∼0.5 M yr −1 ). In 3/4 of the sample the SF is extended on galaxy scales (25-75 kpc), while the rest contains smaller (5-15 kpc) SF patches in the vicinity of an ETG-presumably gas-rich satellites being disrupted. Optical imaging reveals that all ETGs with galaxy-scale SF in our sample have old stellar disks (mostly S0 type). None is classified as a true elliptical. In our sample, galaxy-scale SF takes the form of UV rings of varying sizes and morphologies. For the majority of such objects we conclude that the gas needed to fuel current SF has been accreted from the intergalactic medium, probably in a prolonged, quasi-static manner, leading in some cases to additional disk buildup. The remaining ETGs with galaxy-scale SF have UV and optical morphologies consistent with minor merger-driven SF or with the final stages of SF in fading spirals. Our analysis excludes that all recent SF on the red sequence resulted from gas-rich mergers. We find further evidence that galaxy-scale SF is almost exclusively an S0 phenomenon (∼20% S0s have SF) by examining the overall optically red SDSS ETGs. Conclusion is that significant number of field S0s maintain or resume low-level SF because the preventive feedback is not in place or is intermittent. True ellipticals, on the other hand, stay entirely quiescent even in the field.

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Section: Fading Of the Original Sfmentioning

confidence: 99%

Section: Is Extended Sf In Etgs An S0 Phenomenon?mentioning

confidence: 99%

GALAXY-SCALE STAR FORMATION ON THE RED SEQUENCE: THE CONTINUED GROWTH OF S0s AND THE QUIESCENCE OF ELLIPTICALS

Salim¹,

Fang²,

Rich³

et al. 2012

ApJ

100

112

View full text Add to dashboard Cite

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“…The polar ring itself is gas rich, with a gas fraction corresponding to ∼30 % of the baryonic mass, suggesting that polar-ring galaxies have just accreted a large amount of gas and new stars are formed in situ. Polar rings can be formed through galaxy interaction and merging, but most likely through accretion from cosmic filaments (e.g., Finkelman et al 2011;Pizzella et al 2013;Blasco-Herrera et al 2013). Kinematically distinct inner polar gaseous disks appear common in disk early-type galaxies; their juxtaposition with old stellar nuclei suggests that they may be remnants of gas accretion that occurred prior to the main gas accretion in the galaxy (Sil'chenko and Moiseev 2014; Corsini et al 2012).…”

Section: Kinematical Distortionsmentioning

confidence: 99%

Star formation sustained by gas accretion

Alméida

Elmegreen

Muñoz–Tuñón

et al. 2014

Astron Astrophys Rev

178

130

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Numerical simulations predict that metal-poor gas accretion from the cosmic web fuels the formation of disk galaxies. This paper discusses how cosmic gas accretion controls star formation, and summarizes the physical properties expected for the cosmic gas accreted by galaxies. The paper also collects observational evidence for gas accretion sustaining star formation. It reviews evidence inferred from neutral and ionized hydrogen, as well as from stars. A number of properties characterizing large samples of star-forming galaxies can be explained by metal-poor gas accretion, in particular, the relationship among stellar mass, metallicity, and star-formation rate (the so-called fundamental metallicity relationship). They are put forward and analyzed. Theory predicts gas accretion to be particularly important at high redshift, so indications based on distant objects are reviewed, including the global star-formation history of the universe, and the gas around galaxies as inferred from absorption features in the spectra of background sources.

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“…The Hα velocity fields were analysed with the classical 'tilted-ring' model (Begeman 1989) using the technique described in Finkelman et al (2011);Moiseev (2014). The velocity fields were splitted into elliptical rings in agreement with the adopted inclination (i0) and the position angle of the disc major axis (P A0).…”

Section: Ionized Gas Kinematics and Morphologymentioning

confidence: 99%

H ii versus H i in the ‘green valley’ galaxies: direct comparison

Bryukhareva

Моисеев

2019

Monthly Notices of the Royal Astronomical Society

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We study the morphology and kinematics of the ionization state of the gas in four 'green valley' early-type galaxies at different stages of their transition from a 'blue cloud' of star-forming galaxies to the sequence of passive evolution. The previous H i mapping of the considered sample reveals a spatial offset between the cold gas reservoirs and stellar discs depending on the post-starburst age. Consideration of the ionized-gas properties is essential to understand the role of various feedback processes in star formation quenching. We performed long-slit and 3D optical spectroscopic observations at the 6-m Russian telescope and compared the gas and stellar kinematics. Spatial distribution of the ionized gas is in agreement with H i maps; however, the one-order higher angular resolution in the H ii velocity fields allows us to study noncircular gas motions in detail, like the AGN-driven outflow in the nucleus of J1117+51. The most intriguing result is the global H i+H ii gas counter-rotation relative to the stellar disc in J1237+39. Therefore, in this case all the observed gas in the 'green valley' galaxy was captured from the environment via accretion or minor merging.

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Hoag’s Object: evidence for cold accretion on to an elliptical galaxy

Cited by 32 publications

References 107 publications

GALAXY-SCALE STAR FORMATION ON THE RED SEQUENCE: THE CONTINUED GROWTH OF S0s AND THE QUIESCENCE OF ELLIPTICALS

GALAXY-SCALE STAR FORMATION ON THE RED SEQUENCE: THE CONTINUED GROWTH OF S0s AND THE QUIESCENCE OF ELLIPTICALS

Star formation sustained by gas accretion

H ii versus H i in the ‘green valley’ galaxies: direct comparison

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