A new population of recently quenched elliptical galaxies in the SDSS
| Autor: | C. Wagner, Anna Pasquali, Andrew Cooper, Allison M. Christian, Tim Haines, Anna Gallazzi, Frank C. van den Bosch, Dušan Kereš, Daniel H. McIntosh, Justin Mann, Eric F. Bell |
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| Rok vydání: | 2014 |
| Předmět: |
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
media_common.quotation_subject FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences Spectral line 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics media_common Physics Number density 010308 nuclear & particles physics Center (category theory) Astronomy Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Universe Galaxy Space and Planetary Science Sky Astrophysics of Galaxies (astro-ph.GA) Elliptical galaxy Halo Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 442:533-557 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | We use the Sloan Digital Sky Survey to investigate the properties of massive elliptical galaxies in the local Universe (z\leq0.08) that have unusually blue optical colors. Through careful inspection, we distinguish elliptical from non-elliptical morphologies among a large sample of similarly blue galaxies with high central light concentrations (c_r\geq2.6). These blue ellipticals comprise 3.7 per cent of all c_r\geq2.6 galaxies with stellar masses between 10^10 and 10^11 h^{-2} {\rm M}_{\sun}. Using published fiber spectra diagnostics, we identify a unique subset of 172 non-star-forming ellipticals with distinctly blue urz colors and young (< 3 Gyr) light-weighted stellar ages. These recently quenched ellipticals (RQEs) have a number density of 2.7-4.7\times 10^{-5}\,h^3\,{\rm Mpc}^{-3} and sufficient numbers above 2.5\times10^{10} h^{-2} {\rm M}_{\sun} to account for more than half of the expected quiescent growth at late cosmic time assuming this phase lasts 0.5 Gyr. RQEs have properties that are consistent with a recent merger origin (i.e., they are strong `first-generation' elliptical candidates), yet few involved a starburst strong enough to produce an E+A signature. The preferred environment of RQEs (90 per cent reside at the centers of < 3\times 10^{12}\,h^{-1}{\rm M}_{\sun} groups) agrees well with the `small group scale' predicted for maximally efficient spiral merging onto their halo center and rules out satellite-specific quenching processes. The high incidence of Seyfert and LINER activity in RQEs and their plausible descendents may heat the atmospheres of small host halos sufficiently to maintain quenching. 26 pages, 9 figures. Revised version; accepted for publication in MNRAS |
| Databáze: | OpenAIRE |
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