Maxims Controlled in Ireland (1729)

Fabricant, Carole; Mahony, Robert

doi:10.1057/9780230106895_13

Cited by 8 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Broadly, the overall sample is based on spectra for 463 bright (∼0.2–4.0 L *) Coma cluster members from the SDSS (analysed in Price et al 2011) and 198 fainter members (∼0.02–0.20 L *) observed using long integrations with the Hectospec multi‐fibre spectrograph at the 6.5‐m MMT (Fabricant et al 2005). A detailed description of the sample construction, parameter measurements and methods, and data presentation, will be presented in a separate paper (Smith et al, in preparation, hereafter S11).…”

Section: Coma Observations and Age Correlationsmentioning

confidence: 99%

Environmental quenching and hierarchical cluster assembly: evidence from spectroscopic ages of red-sequence galaxies in Coma

Smith

Lucey

Price

et al. 2011

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We explore the variation in stellar population ages for Coma cluster galaxies as a function of projected cluster‐centric distance, using a sample of 362 red‐sequence galaxies with high signal‐to‐noise ratio spectroscopy. The sample spans a wide range in luminosity (0.02–4 L*) and extends from the cluster core to near the virial radius. We find a clear distinction in the observed trends of the giant and dwarf galaxies. The ages of red‐sequence giants are primarily determined by galaxy mass, whether parametrized by velocity dispersion, luminosity, stellar mass or dynamical mass, with only weak modulation by environment, in the sense that galaxies at larger cluster‐centric distance are slightly younger. For red‐sequence dwarfs (with mass ≲ 1010 M⊙), the roles of mass and environment as predictors of age are reversed: there is little dependence on mass, but strong trends with projected cluster‐centric radius are observed. The average age of dwarfs at the 2.5 Mpc limit of our sample is approximately half that of dwarfs near the cluster centre. The gradient in dwarf galaxy ages is a global cluster‐centric trend, and is not driven by the ongoing merger of the NGC 4839 group to the south west of Coma. We interpret these results using environmental histories extracted from the Millennium Simulation for members of massive clusters. Hierarchical cluster assembly naturally leads to trends in the accretion times of galaxies as a function of projected cluster‐centric radius. On average, simulated galaxies now located in cluster cores joined haloes above any given mass threshold earlier than those now in the outskirts of clusters. We test environmental quenching models, in which star formation is halted in galaxies when they enter haloes of a given mass, or when they become satellites. Our models broadly reproduce the gradients observed in Coma, but for dwarf galaxies the efficiency of environmental quenching must be very high to match the strong trends observed.

show abstract

Section: Coma Observations and Age Correlationsmentioning

confidence: 99%

Environmental quenching and hierarchical cluster assembly: evidence from spectroscopic ages of red-sequence galaxies in Coma

Smith

Lucey

Price

et al. 2011

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Spectra were obtained at the 6.5‐m MMT using the Hectospec fibre‐fed spectrograph (Fabricant et al 2005), in parallel with a redshift survey of faint candidate cluster members (Marzke et al, in preparation). The observations were performed in queue‐mode over the period 2007 February–April, mainly within five days of new moon.…”

Section: Datamentioning

confidence: 99%

A spectroscopic survey of dwarf galaxies in the Coma cluster: stellar populations, environment and downsizing

Smith¹,

Lucey²,

Hudson

et al. 2009

Monthly Notices of the Royal Astronomical Society

101

124

View full text Add to dashboard Cite

We investigate the stellar populations in a sample of 89 faint red galaxies in the Coma cluster, using high signal‐to‐noise ratio (S/N) spectroscopy from the 6.5‐m MMT. Our sample is drawn from two 1° fields, one centred on the cluster core and the other located 1° to the south‐west of the cluster centre. The target galaxies are mostly 2–4 mag fainter than M*; galaxies with these luminosities have been previously studied only using small samples, or at low S/N. For a comparison sample we use published high‐S/N data for red‐sequence galaxies in the Shapley supercluster. We use state‐of‐the‐art stellar population models (by R. Schiavon) to interpret the absorption‐line indices and infer the single‐burst‐equivalent age and metallicity (Fe/H) for each galaxy, as well as the abundances of the light elements Mg, Ca, C and N. The ages of the Coma dwarfs span a wide range from <2 Gyr to >10 Gyr, with a strong environmental dependence. The oldest galaxies are found only in the core, while most of the galaxies in the outer south‐west field have ages ∼3 Gyr. The galaxies have a metallicity range −1.0 ≲[Fe/H]≲ 0.0, and follow the same age–metallicity–mass plane as high‐mass galaxies, but with increased intrinsic scatter. The Mg/Fe abundance ratios are on average slightly supersolar, and span a range −0.1 ≲[Mg/Fe]≲+0.4. The highest Mg enhancements are found only in the cluster core, while solar ratios predominate in the outskirts. We show that parametrized models with more complex star formation histories perform no better than single‐burst models in reproducing the observed line indices. Assuming a star formation history dominated by a single burst, the number of dwarf galaxies on the red sequence in the Coma core has doubled since z≈ 0.7. Assuming instead an abruptly truncated constant star formation rate, the equivalent redshift is z≈ 0.4. These estimates bracket the red‐sequence growth time‐scales found by direct studies of distant clusters. In the south‐west field, the red sequence was established only at z≈ 0.2 for a burst‐dominated star formation history (z≈ 0.1 for the truncated case). Our observations confirm previous indications of very recently quenched star formation in this part of the cluster. Our results strongly support the scenario in which much of the cluster passive dwarf population (in this luminosity range) was generated by environment‐driven transformation of infalling late‐type galaxies.

show abstract

“…As part of the ACS Coma Cluster Survey, we are carrying out a comprehensive spectroscopic survey of galaxies in the Coma region using Hectospec, a 300‐fibre spectrograph at the MMT (Fabricant et al 2005). Observing time was allocated for this survey by the National Optical Astronomy Observatory (NOAO) time allocation committee through the NSF/TSIP program.…”

Section: Observationsmentioning

confidence: 99%

TheHST/ACS Coma Cluster Survey - V. Compact stellar systems in the Coma Cluster

Price

Phillipps

Huxor

et al. 2009

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) Coma Cluster Treasury Survey is a deep two‐passband imaging survey of the nearest very rich cluster of galaxies, covering a range of galaxy density environments. The imaging is complemented by a recent wide field redshift survey of the cluster conducted with Hectospec on the 6.5‐m Monolithic Mirror Telescope (MMT). Among the many scientific applications for these data is the search for compact galaxies. In this paper, we present the discovery of seven compact (but quite luminous) stellar systems, ranging from M32‐like galaxies down to ultra‐compact dwarfs (UCDs)/dwarf to globular transition objects (DGTOs). We find that all seven compact galaxies require a two‐component fit to their light profile and have measured velocity dispersions that exceed those expected for typical early‐type galaxies at their luminosity. From our structural parameter analysis, we conclude that three of the samples should be classified as compact ellipticals or M32‐like galaxies, and the remaining four being less extreme systems. The three compact ellipticals are all found to have old luminosity weighted ages (≳12 Gyr), intermediate metallicities (−0.6 < [Fe/H] < −0.1) and high [Mg/Fe] (≳0.25). Our findings support a tidal stripping scenario as the formation mode of compact galaxies covering the luminosity range studied here. We speculate that at least two early‐type morphologies may serve as the progenitor of compact galaxies in clusters.

show abstract

Maxims Controlled in Ireland (1729)

Cited by 8 publications

References 0 publications

Environmental quenching and hierarchical cluster assembly: evidence from spectroscopic ages of red-sequence galaxies in Coma

Environmental quenching and hierarchical cluster assembly: evidence from spectroscopic ages of red-sequence galaxies in Coma

A spectroscopic survey of dwarf galaxies in the Coma cluster: stellar populations, environment and downsizing

TheHST/ACS Coma Cluster Survey - V. Compact stellar systems in the Coma Cluster

Contact Info

Product

Resources

About