Internal Dynamics, Structure, and Formation of Dwarf Elliptical Galaxies. II. Rotating versus Nonrotating Dwarfs

By M. Geha, P. Guhathakurta, R. P. van der Marel. 2002

256 citations recorded by the source corpus.

We present spatially resolved internal kinematics and stellar chemical abundances for a sample of dwarf elliptical (dE) galaxies in the Virgo Cluster observed with the Keck telescope and Echelle Spectrograph and Imager. In combination with previous measurements, we find that four out of 17 dE's have major-axis rotation velocities consistent with rotational flattening, while the remaining dE's have no detectable major-axis rotation. Despite this difference in internal kinematics, rotating and nonrotating dE's are remarkably similar in terms of their position in the fundamental plane, morphological details, stellar populations, and local environment. We present evidence for (or confirm the presence of) faint underlying disks and/or weak substructure in a fraction of both rotating and nonrotating dE's, but a comparable number of counterexamples exist for both types that show no evidence of such structure. Absorption line strengths were determined based on the Lick/IDS system (Hβ, Mg b, Fe5270, and Fe5335) for the central region of each galaxy. We find no difference in the line-strength indices, and hence stellar populations, between rotating and nonrotating dE galaxies. The best-fitting mean age and metallicity for our same of 17 dE's are 5 Gyr and [Fe/H] = -0.3 dex, respectively, with rms spreads of 3 Gyr and 0.1 dex. The majority of dE's are consistent with solar [α/Fe] abundance ratios. By contrast, the stellar populations of classical elliptical galaxies are, on average, older, more metal-rich, and α-enhanced relative to our dE sample. The line strengths of our dE's are consistent with the extrapolation of the line strength versus velocity dispersion trend seen in classical elliptical galaxies. Finally, the local environments of both rotating and nonrotating dE's appear to be diverse in terms of their proximity to larger galaxies in real or velocity space within the Virgo Cluster. Thus, rotating and nonrotating dE's are remarkably similar in terms of their structure, stellar content, and local environments, presenting a significant challenge to theoretical models of their formation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0573a5dc59f4976ce2082b30c9ba9c8bc8300595

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Citations in the corpus

Precession of the Sagittarius stream (2013, background): “…the UCDs at least a magnitude more luminous, they also appear to have somewhat inflated velocity dispersions, as evident from the inferred mass-to-light ratios of∼ 5− 10 c© 2012 RAS, MNRAS000, 1–12 similar to that of the nuclei of dwarf ellipticals in clusters of galaxies (e.g. Geha et al. 2002).”
Nuclear star clusters (2009, unknown): “…Gültekin et al. (2009), (18) Saglia et al. (2016), (19) Pechetti et al. (2017), (20) Gebhardt et al. (2001), (21) Neumayer and Walcher (2012), (22) Geha et al. (2002), (23) Barth et al. (2009), (24) Böker et al. (1999), (25) Gebhardt et al. (2011), (26) Bower et al. (1998), (27) Rusli et al.…”
The Mass Function of Active Black Holes in the Local Universe (2007, background): “This is because dwarf spheroidal galaxies are more luminous than elliptical galaxies at the sameσ∗ (e.g., Geha et al. 2003).”
Masses of Star Clusters in the Nuclei of Bulgeless Spiral Galaxies (2004, methodology): “We used the formalism described in Geha et al. (2002) to calculate several test models for one of the sample galaxies in which we assumed different values for (M/L)cluster and (M/L)disk.”
Virgo Cluster Early-Type Dwarf Galaxies with the Sloan Digital Sky Survey. II. Early-Type Dwarfs with Central Star Formation (2006, methodology): “For this purpose we use V-band mass-to-light ratios between 3 and 6, as given by Geha et al. (2003), and assume no dark matter content, again following Geha et al. (2003).”
Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation (2010, background): “Viewing dE galaxies as TDGs would also be consistent with the observation that they have essentially stellar mass-to-light ratios similar to globular clusters (Bender et al. 1992; Geha et al. 2003; Dabringhausen et al. 2008; Forbes et al. 2008).”
The Origin of Dwarf Ellipticals in the Virgo Cluster (2008, methodology): “…line uncontaminated by the Hβ emission, which might be present whenever star formation is still active 15 SDSS, Michielsen et al. (2007) and Geha et al. (2003) spectroscopic Hα and Hβ data are limited to the central 3-4 arcsec of the observed galaxies, and are thus not directly comparable…”
Masses and scaling relations for nuclear star clusters, and their co-existence with central black holes (2016, unknown): “…(NSC) and/or a super massive black hole (SMBH), with NSCs being identified in more than > 60− 70% of early- (e.g. Durrell 1997; Carollo et al. 1998; Geha et al. 2002; Lotz et al. 2004; Côté et al. 2006; Turner et al. 2012; den Brok et al. 2014) and late-type galaxies (e.g. Böker et al. 2002,…”
Hubble Space Telescope STIS Spectra of Nuclear Star Clusters in Spiral Galaxies: Dependence of Age and Mass on Hubble Type (2006, background): “These similarities extend also to related objects such as the nuclei of dwarf elliptical galaxies (Geha et al. 2002) and the so-called “ultra-compact dwarf” galaxies (Haşegan et al. 2005).”
DISSIPATION AND EXTRA LIGHT IN GALACTIC NUCLEI. II. “CUSP” ELLIPTICALS (2008, background): “If we include the limited subsample of stellar nuclei with velocity dispersions measured in Geha et al. (2002) and Walcher et al. (2005), we find similar results in fundamental projections involving σ .”