H I observations of elliptical galaxies

Knapp, G. R.; Kerr, F. J.; Williams, B. A.

doi:10.1086/156199

Cited by 39 publications

(23 citation statements)

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“…For example, in the simulations of Kereš et al (2009) haloes of mass of 10 12 M ⊙ have ∼ 5 percent of gas colder than 250,000 K, but this drops to ∼ 0 percent for a halo mass of 10 13 M ⊙ . This is qualitatively consistent with observations: for example massive elliptical galaxies and FRI radio galaxies typically have relatively little Hi gas (Knapp, Kerr & Williams 1978;Morganti et al 2001;Serra et al 2012). The lack of star formation in the LERG population also points to a deficit of cold gas and their stellar mass (∼ 10 11 h −2 M ⊙ ) is in the regime where cold gas accretion is not expected to be important (e.g.…”

Section: The Triggering Of Lergssupporting

confidence: 89%

Galaxy And Mass Assembly (GAMA): the environments of high- and low-excitation radio galaxies

Ching

Croom

Sadler

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We study the environments of low-and high-excitation radio galaxies (LERGs and HERGs respectively) in the redshift range 0.01 < z < 0.4, using a sample of 399 radio galaxies and environmental measurements from the Galaxy And Mass Assembly (GAMA) survey. In our analysis we use the fifth nearest neighbour density (Σ 5 ) and the GAMA galaxy groups catalogue (G3Cv6) and construct control samples of galaxies matched in stellar mass and colour to the radio-detected sample.We find that LERGs and HERGs exist in different environments and that this difference is dependent on radio luminosity. High-luminosity LERGs (L NVSS 10 24 W Hz −1 ) lie in much denser environments than a matched radio-quiet control sample (about three times as dense, as measured by Σ 5 ), and are more likely to be members of galaxy groups (82 +5 −7 percent of LERGs are in GAMA groups, compared to 58 +3 −3 percent of the control sample). In contrast, the environments of the HERGs and lower luminosity LERGs are indistinguishable from that of a matched control sample. Our results imply that high-luminosity LERGs lie in more massive haloes than non-radio galaxies of similar stellar mass and colour, in agreement with earlier studies (Wake et al. 2008;Donoso et al. 2010). When we control for the preference of LERGs to be found in groups, both high-and low-luminosity LERGs are found in higher-mass haloes (∼ 0.2 dex; at least 97 percent significant) than the non-radio control sample.

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Section: The Triggering Of Lergssupporting

confidence: 89%

Galaxy And Mass Assembly (GAMA): the environments of high- and low-excitation radio galaxies

Ching

Croom

Sadler

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…The general absence of observable HI supports this view point (e.g. Huchtmeier et al 1977, Knapp et al 1978b). All evidence suggests that star formation in elliptical galaxies lasted just a short time and ceased long ago.…”

Section: Elliptical Galaxiesmentioning

confidence: 62%

Star Formation in the Nuclei of Normal Galaxies

Biermann

1980

Highlights astron.

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For the purpose of this talk, I define all those galaxies as normal whose nuclear regions are not known to be dominated by a compact source. Thus I will exclude N galaxies, Seyfert galaxies and radio galaxies, but include galaxies like M81 and M82 which have weak compact nuclei. My review is organized in three parts, (i) tracers of star formation, (ii) star formation in the nuclear regions of observed galaxies, and (iii) the theoretical attempts to interpret the observational material.

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“…(e.g., Knapp, Kerr, & Williams 1978). Here D is the galaxy distance in megaparsecs and P S v dv is the total 21 cm line flux in jansky kilometers per second.…”

Section: Baryon Content: Stellar Luminosities and H I Massesmentioning

confidence: 99%

The Progenitors of Dwarf Spheroidal Galaxies

Grebel¹,

Gallagher²,

Harbeck³

2003

The Astronomical Journal

481

702

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The gas-deficient dwarf spheroidal (dSph) galaxies present an evolutionary puzzle that we explore in 40 early-type and late-type dwarfs in the Local Group and nearby field. Although dSph's experienced star formation over extended time spans in their youths, today all but one are completely free of detectable interstellar material, even in the Fornax dSph, where stars formed in the last 100 Myr. Combining photometric and spectroscopic stellar metallicity estimates for red giant branches with high-sensitivity H i 21 cm line data from the literature, we show that the well-established offset in luminosity-metallicity relationships for dSph's and dwarf irregular (dIrr) galaxies exists also when confining the comparison to their old stellar populations: dSph's have higher mean stellar metallicities for a fixed optical luminosity. Evidently star formation in younger dSph's was more vigorous than in the youthful dIrr's, leading to more efficient enrichment. Dwarf galaxies, whose locus in the luminosity-metallicity diagram is consistent with that of dSph's, even when baryonic luminosities are considered, are the '' transition-type dwarfs '' Phoenix, DDO 210, LGS 3, Antlia, and KKR 25. These dwarfs have mixed dIrr/dSph morphologies, low stellar masses, low angular momentum, and H i contents of at most a few 10 6 M . Unlike dIrr's many transition-type dwarfs would closely resemble dSph's if their gas were removed, as required to become a dSph; they are likely dSph progenitors. As gas removal is the key factor for such a transition, we consider the empirical evidence in favor and against various gas removal processes. We suggest that internal gas removal mechanisms are inadequate and favor ram-pressure stripping to clean the bulk of interstellar matter from galaxies to make dSph's. A combination of initial conditions and environment seems to support the formation of dSph's: nearby dSph's appear to form from small galaxies with active early star formation, whose evolution halts due to externally induced gas loss. Transition-type dwarfs, then, are dSph's that kept their interstellar medium and therefore should replace dSph's in isolated locations where stripping is ineffective.

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H I observations of elliptical galaxies

Cited by 39 publications

References 0 publications

Galaxy And Mass Assembly (GAMA): the environments of high- and low-excitation radio galaxies

Galaxy And Mass Assembly (GAMA): the environments of high- and low-excitation radio galaxies

Star Formation in the Nuclei of Normal Galaxies

The Progenitors of Dwarf Spheroidal Galaxies

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