Kinematics of Ten Early-Type Galaxies from Hubble Space Telescope and Ground-Based SPECTROSCOPY1 (original) (raw)
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Kinematics of 10 Early‐Type Galaxies from Hubble Space Telescope and Ground‐based Spectroscopy
The Astrophysical Journal, 2003
We present stellar kinematics for a sample of 10 early-type galaxies observed using the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope, and the Modular Spectrograph on the MDM Observatory 2.4-m telescope. These observations are a part of an ongoing program to understand the co-evolution of supermassive black holes and their host galaxies. Our spectral ranges include either the calcium triplet absorption lines at 8498, 8542, and 8662 Å, or the Mg b absorption at 5175 Å. The lines are used to derive line-of-sight velocity distributions (LOSVDs) of the stars using a Maximum Penalized Likelihood method. We use Gauss-Hermite polynomials to parameterize the LOSVDs and find predominantly negative h4 values (boxy distributions) in the central regions of our galaxies. One galaxy, NGC 4697, has significantly positive central h4 (high tail weight). The majority of galaxies have a central velocity dispersion excess in the STIS kinematics over ground-based velocity dispersions. The galaxies with the strongest rotational support, as quantified with v MAX /σ ST IS , have the smallest dispersion excess at STIS resolution.
Kinematics of Ten Early-Type Galaxies from HST and Ground-Based Spectroscopy
2003
We present stellar kinematics for a sample of 10 early-type galaxies observed using the STIS aboard the Hubble Space Telescope, and the Modular Spectrograph on the MDM Observatory 2.4-m telescope. The spectra are used to derive line-of-sight velocity distributions (LOSVDs) of the stars using a Maximum Penalized Likelihood method. We use Gauss-Hermite polynomials to parameterize the LOSVDs and find predominantly negative h4 values (boxy distributions) in the central regions of our galaxies. One galaxy, NGC 4697, has significantly positive central h4 (high tail weight). The majority of galaxies have a central velocity dispersion excess in the STIS kinematics over ground-based velocity dispersions. The galaxies with the strongest rotational support, as quantified with v_MAX/sigma_STIS, have the smallest dispersion excess at STIS resolution. The best-fitting, general, axisymmetric dynamical models (described in a companion paper) require black holes in all cases, with masses ranging from 10^6.5 to 10^9.3 Msun. We replot these updated masses on the BH/sigma relation, and show that the fit to only these 10 galaxies has a slope consistent with the fits to larger samples. The greatest outlier is NGC 2778, a dwarf elliptical with relatively poorly constrained black hole mass. The two best candidates for pseudobulges, NGC 3384 and 7457, do not deviate significantly from the established relation between black hole and sigma. Neither do the three galaxies which show the most evidence of a recent merger, NGC 3608, 4473, and 4697.
Chemo-kinematics of the Milky Way from the SDSS-III MARVELS survey
Monthly Notices of the Royal Astronomical Society, 2018
Combining stellar atmospheric parameters, such as effective temperature, surface gravity, and metallicity, with barycentric radial velocity data provides insight into the chemo-dynamics of the Milky Way and our local Galactic environment. We analyse 3075 stars with spectroscopic data from the Sloan Digital Sky Survey III MARVELS radial velocity survey and present atmospheric parameters for 2343 dwarf stars using the spectral indices method, a modified version of the equivalent width method. We present barycentric radial velocities for a sample of 2610 stars with a median uncertainty of 0.3 km s −1. We determine stellar ages using two independent methods and calculate ages for 2335 stars with a maximum-likelihood isochronal age-dating method and for 2194 stars with a Bayesian age-dating method. Using previously published parallax data, we compute Galactic orbits and space velocities for 2504 stars to explore stellar populations based on kinematic and age parameters. This study combines good ages and exquisite velocities to explore local chemo-kinematics of the Milky Way, which complements many of the recent studies of giant stars with the APOGEE survey, and we find our results to be in agreement with current chemo-dynamical models of the Milky Way. Particularly, we find from our metallicity distributions and velocity-age relations of a kinematically defined thin disc that the metal-rich end has stars of all ages, even after we clean the sample of highly eccentric stars, suggesting that radial migration plays a key role in the metallicity scatter of the thin disc. All stellar parameters and kinematic data derived in this work are catalogued and published online in machine-readable form.
Line-of-sight velocity distributions of 53 early-type galaxies
Astronomy and Astrophysics Supplement Series, 2000
55 long-slit spectra of 53 early-type galaxies were observed at La Silla/ESO and reduced using standard methods. The line-of-sight velocity distributions (LOSVDs) were measured using the fourier quotient method and the fourier fitting method as described by van der Marel et al. (1993). 32% of the examined galaxies contain kinematically decoupled stellar omponents, the size of these cores was 0.40 ± 0.28 kpc, in each case the core was smaller than 1 kpc. Analysis of the kinematics reveals in 49% of the sample galaxies the signature of a stellar disk component, in 15% this is uncertain. There is evidence that the phenomenon of kinematically decoupled components is present in the whole class of early-type galaxies. Several correlations between photometric and kinematic parameters like the (v/σ) * vs. diagram, the anisotropy-luminosity correlation or κ-space were as well examined using measurement results for spectroscopic data and photometric data out of literature. It is also shown that those sample galaxies with kinematically decoupled components are more likely to be found in groups of high density, strengthening the assumption that such components are remnants of merging events.
The Astrophysical Journal Supplement Series, 1997
We present peculiar velocities for 85 clusters of galaxies in two large volumes at distances between 6000 and 15 000 km s 21 in the directions of Hercules±Corona Borealis and Perseus±Pisces±Cetus (the EFAR sample). These velocities are based on Fundamental Plane (FP) distance estimates for early-type galaxies in each cluster. We fit the FP using a maximum likelihood algorithm which accounts for both selection effects and measurement errors, and yields FP parameters with smaller bias and variance than other fitting procedures. We obtain a best-fitting FP with coefficients consistent with the best existing determinations. We measure the bulk motions of the sample volumes using the 50 clusters with the bestdetermined peculiar velocities. We find that the bulk motions in both regions are small, and consistent with zero at about the 5 per cent level. The EFAR results are in agreement with the small bulk motions found by Dale et al. on similar scales, but are inconsistent with pure dipole motions having the large amplitudes found by Lauer & Postman and Hudson et al. The alignment of the EFAR sample with the Lauer & Postman dipole produces a strong rejection of a large-amplitude bulk motion in that direction, but the rejection of the Hudson et al. result is less certain because their dipole lies at a large angle to the main axis of the EFAR sample. We employ a window function covariance analysis to make a detailed comparison of the EFAR peculiar velocities with the predictions of standard cosmological models. We find that the bulk motion of our sample is consistent with most cosmological models that approximately reproduce the shape and normalization of the observed galaxy power spectrum. We conclude that existing measurements of large-scale bulk motions provide no significant evidence against standard models for the formation of structure.
The Milky Way Tomography with SDSS. III. Stellar Kinematics
Astrophysical Journal, 2010
We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r < 20 and proper-motion measurements derived from SDSS and POSS astrometry, including ∼170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric parallax relation, covering a distance range from ∼100 pc to 10 kpc over a quarter of the sky at high Galactic latitudes (|b| > 20 • ). We find that in the region defined by 1 kpc < Z < 5 kpc and 3 kpc < R < 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multimodal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and LSST.
The SLUGGS Survey: kinematics for over 2500 globular clusters in 12 early-type galaxies
Monthly Notices of the Royal Astronomical Society, 2013
We present a spectro-photometric survey of 2522 extragalactic globular clusters (GCs) around twelve early-type galaxies, nine of which have not been published previously. Combining space-based and multi-colour wide field ground-based imaging, with spectra from the Keck DEIMOS instrument, we obtain an average of 160 GC radial velocities per galaxy, with a high velocity precision of ∼ 15 km s −1 per GC. After studying the photometric properties of the GC systems, such as their spatial and colour distributions, we focus on the kinematics of metal-poor (blue) and metal-rich (red) GC subpopulations to an average distance of ∼ 8 effective radii from the galaxy centre.
The Astrophysical Journal Supplement Series, 2012
We present high-quality Keck/LRIS longslit spectroscopy of a pilot sample of 25 local active galaxies selected from the SDSS (0.02 ≤ z ≤ 0.1; M BH > 10 7 M ⊙) to study the relations between black hole mass (M BH) and host-galaxy properties. We determine stellar kinematics of the host galaxy, deriving stellar-velocity dispersion profiles and rotation curves from three spectral regions (including CaH&K, MgIb triplet, and CaII triplet). In addition, we perform surface photometry on SDSS images, using a newly developed code for joint multi-band analysis. BH masses are estimated from the width of the Hβ emission line and the host-galaxy free 5100Å AGN luminosity. Combining results from spectroscopy and imaging allows us to study four M BH scaling relations: M BH-σ, M BH-L sph , M BH-M sph,⋆ , and M BH-M sph,dyn. We find the following results. First, stellar-velocity dispersions determined from aperture spectra (e.g. SDSS fiber spectra or unresolved data from distant galaxies) can be biased, depending on aperture size, AGN contamination, and host-galaxy morphology. However, such a bias cannot explain the offset seen in the M BH-σ relation at higher redshifts. Second, while the CaT region is the cleanest to determine stellar-velocity dispersions, both the MgIb region, corrected for FeII emission, and the CaHK region, although often swamped by the AGN powerlaw continuum and emission lines, can give results accurate to within a few percent. Third, the M BH scaling relations of our pilot sample agree in slope and scatter with those of other local active and inactive galaxies. In the next papers of the series we will quantify the scaling relations, exploiting the full sample of ∼ 100 objects.
Kinematic and chemical evolution of early-type galaxies
Astronomy and Astrophysics, 2005
We investigate in detail 13 early-type field galaxies with 0.2 < z < 0.7 drawn from the F Deep Field. Since the majority (9 galaxies) is at z ≈ 0.4, we compare the field galaxies to 22 members of three rich clusters with z = 0.37 to explore possible variations caused by environmental effects. We exploit VLT/FORS spectra (R ≈ 1200) and HST/ACS imaging to determine internal kinematics, structures and stellar population parameters. From the Faber-Jackson and Fundamental Plane scaling relations we deduce a modest luminosity evolution in the B-band of 0.3-0.5 mag for both samples. We compare measured Lick absorption line strengths (Hδ, Hγ, Hβ, Mg b , and Fe 5335) with evolutionary stellar population models to derive light-averaged ages, metallicities and the element abundance ratios Mg/Fe. We find that these three stellar parameters of the distant galaxies obey a scaling with velocity dispersion (mass) which is consistent with that of local nearby galaxies. In particular, the distribution of Mg/Fe ratios of local galaxies is matched by the distant ones, and their derived mean offset in age corresponds to the average lookback time. This indicates that there was little chemical enrichment and no significant star formation within the last ∼5 Gyr. The calculated luminosity evolution of a simple stellar population model for the derived galaxy ages and lookback times is in most cases consistent with the mild brightening measured by the scaling relations.
THE SLUGGS SURVEY: WIDE-FIELD STELLAR KINEMATICS OF EARLY-TYPE GALAXIES
The Astrophysical Journal, 2014
We present stellar kinematics of 22 nearby early-type galaxies (ETGs), based on two-dimensional (2D) absorption line stellar spectroscopy out to ∼ 2-4 R e (effective radii), as part of the ongoing SLUGGS survey. The galaxies span a factor of 20 in intrinsic luminosity, as well as a full range of environment and ETG morphology. Our data consist of good velocity resolution (σ inst ∼ 25 km s −1 ) integrated stellar-light spectra extracted from the individual slitlets of custom made Keck/DEIMOS slitmasks. We extract stellar kinematics measurements (V , σ, h 3 , and h 4 ) for each galaxy. Combining with literature values from smaller radii we present 2D spatially resolved maps of the large-scale kinematic structure in each galaxy. We find that the kinematic homogeneity found inside 1 R e often breaks down at larger radii, where a variety of kinematic behaviors are observed. While central slow rotators remain slowly rotating in their halos, central fast rotators show more diversity, ranging from rapidly increasing to rapidly declining specific angular momentum profiles in the outer regions. There are indications that the outer trends depend on morphological type, and we suggest that the apparent unification of the elliptical and lenticular (S0) galaxy families in the ATLAS 3D survey may be a consequence of a limited field of view. Several galaxies in our sample show multiple lines of evidence for distinct disk components embedded in more slowly rotating spheroids, and we suggest a joint photometric-kinematic approach for robust bulge-disk decomposition. Our observational results appear generally consistent with a picture of two-phase (in-situ plus accretion) galaxy formation.