An atlas of Calcium triplet spectra of active galaxies (original) (raw)
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Monthly Notices of the Royal Astronomical Society, 2014
We examine the stellar velocity dispersions (σ) of a sample of 48 galaxies, 35 of which are spirals, from the Palomar nearby galaxy survey. It is known that for ultra-luminous infrared galaxies (ULIRGs) and merger remnants the σ derived from the near-infrared CO band-heads is smaller than that measured from optical lines, while no discrepancy between these measurements is found for early-type galaxies. No such studies are available for spiral galaxies -the subject of this paper. We used cross-dispersed spectroscopic data obtained with the Gemini Near-Infrared Spectrograph (GNIRS), with spectral coverage from 0.85 to 2.5 µm, to obtain σ measurements from the 2.29 µm CO band-heads (σ CO ), and the 0.85 µm calcium triplet (σ CaT ). For the spiral galaxies in the sample, we found that σ CO is smaller than σ CaT , with a mean fractional difference of 14.3 %. The best fit to the data is given by σ opt = (46.0 ± 18.1) + (0.85 ± 0.12)σ CO . This "σ discrepancy" may be related to the presence of warm dust, as suggested by a slight correlation between the discrepancy and the infrared luminosity. This is consistent with studies that have found no σ−discrepancy in dust-poor early-type galaxies, and a much larger discrepancy in dusty merger remnants and ULIRGs. That σ CO is lower than σ opt may also indicate the presence of a dynamically cold stellar population component. This would agree with the spatial correspondence between low σ CO and young/intermediate-age stellar populations that has been observed in spatially-resolved spectroscopy of a handful of galaxies.
Kinematics of Ten Early-Type Galaxies from Hubble Space Telescope and Ground-Based SPECTROSCOPY1
2003
We present stellar kinematics for a sample of 10 early-type g alaxies 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 o ngoing program to understand the co-evolution of supermassive black holes and their host galaxies. Our spect ral 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-si ght velocity distributions (LOSVDs) of the stars using a Maximum Pena lized Likelihood method. We use Gauss-Hermite polynomials to parameterize the LOSVDs and find predominant ly negativeh4 values (boxy distributions) in the central regions of our galaxies. One galaxy, NGC 4697, has si gnificantly positive central h4 (high tail weight). The majority of galaxies have a central velocity dispersion exc ess in the STIS kinematics over ground-based ...
The Near-Infrared Ca ii Triplet- Relation for Bulges of Spiral Galaxies
The Astrophysical Journal, 2003
We present measurements of the near-infrared Calcium II triplet (CaT, CaT *), Paschen (PaT) and Magnesium (Mg I) indices for a well-studied sample of 19 bulges of early to intermediate spiral galaxies. We find that both the CaT * and CaT indices decrease with central velocity dispersion σ with small scatter. This dependence is similar to that recently found by Cenarro (2002) for elliptical galaxies, implying an uniform CaT *-σ relation that applies to galaxies from ellipticals to intermediate-type spirals. The decrease of CaT and CaT * with σ contrasts with the well-known increase of another α-element index, Mg 2 , with σ. We discuss the role of Ca underabundance ([Ca/Fe]<0) and IMF variations in the onset of the observed relations.
The Puzzlingly Small C[CLC]a[/CLC] [CSC]ii[/CSC] Triplet Absorption in Elliptical Galaxies
The Astrophysical Journal, 2002
We measure the central values (within R e /8) of the CaII triplet line indices CaT * and CaT and the Paschen index PaT at 8600Å for a 93%-complete sample of 75 nearby early-type galaxies with B T < 12 and V gal < 2490. We find that the values of CaT * are constant to within 5% over the range of central velocity dispersions 100 ≤ σ ≤ 340 km/s, while the PaT (and CaT) values are mildly anti-correlated with σ. Using simple and composite stellar population models, we show that: a) The measured CaT * and CaT are lower than expected from simple stellar population models (SSPs) with Salpeter initial mass functions (IMFs) and with metallicities and ages derived from optical Lick (Fe, Mg and Hβ) indices. Uncertainties in the calibration, the fitting functions and the SSP modeling taken separately cannot explain the discrepancy. On the average, the observed PaT values are within the range allowed by the models and the large uncertainties in the fitting functions. b) The steepening of the IMF at low masses required to lower the CaT * and CaT indices to the observed values is incompatible with the measured FeH index at 9916Å and the dynamical mass-to-light ratios of ellipticals. c) Composite stellar populations with a low-metallicity component reduce the disagreement, but rather artificial metallicity distributions are needed. Another explanation may be that calcium is indeed underabundant in ellipticals.
The Puzzlingly Large Ca ii Triplet Absorption in Dwarf Elliptical Galaxies
The Astrophysical Journal, 2003
We present central CaT, PaT, and CaT* indices for a sample of fifteen dwarf elliptical galaxies (dEs). Twelve of these have CaT*∼ 7Å and extend the negative correlation between the CaT* index and central velocity dispersion σ, which was derived for bright ellipticals (Es), down to 20 < σ < 55 km/s. For five dEs we have independent age and metallicity estimates. Four of these have CaT*∼ 7Å, much higher than expected from their low metallicities (−1.5 < [Z/H] < −0.5). The observed anti-correlation of CaT* as a function of σ or Z is in flagrant disagreement with theory. We discuss some of the amendments that have been proposed to bring the theoretical predictions into agreement with the observed CaT*-values of bright Es and how they can be extended to incorporate also the observed CaT*-values of dEs. Moreover, 3 dEs in our sample have CaT*∼ 5Å, as would be expected for metal-poor stellar systems. Any theory for dE evolution will have to be able to explain the co-existence of low-CaT* and high-CaT* dEs at a given mean metallicity. This could be the first direct evidence that the dE population is not homogeneous, and that different evolutionary paths led to morphologically and kinematically similar but chemically distinct objects.
Stellar indices and kinematics in Seyfert 1 nuclei
Monthly Notices of the Royal Astronomical Society, 2000
We present spectra of 6 type 1 Seyfert galaxies, 2 Seyfert 2, a starburst galaxy and a compact narrow line radiogalaxy, taken in two spectral ranges centered around the near-IR Ca ii triplet (∼ 8600Å ), and the Mgb stellar feature at 5180Å. We measured the equivalent width (EWs) of these features and the Fe 52 and Fe 53 spectral indices.
Early-Type Galaxies in the Coma Cluster: A New Piece in the Calcium Puzzle
Astrophysical Journal, 2004
We present measurements of the Ca ii triplet and the Ca4227 Lick-index for a sample of early-type galaxies in the Coma cluster, deriving, for the first time, their corresponding relationships with velocity dispersion. Compared with a similar subsample of ellipticals in the field, Coma galaxies with velocity dispersions in the range ≈ 180 − 270 km s −1 exhibit significant differences in the strengths of the Ca features, suggesting an influence of the environment on the star formation histories of these galaxies. We argue that the main scenarios previously proposed to explain the relatively low Ca ii triplet of galaxies are not able by themselves to simultaneously reconcile the strengths of the two Ca indices in both environments.
Monthly Notices of the Royal Astronomical Society, 2009
We describe a new technique to measure stellar kinematics and line-strengths at large radii in nearby galaxies. Using the integral-field spectrograph SAURON as a 'photon-collector', we obtain spectra out to four effective radii (R e ) in the early-type galaxy NGC 3379. By fitting orbit-based models to the extracted stellar velocity profile, we find that ∼ 40% of the total mass within 5 R e is dark. The measured absorption line-strengths reveal a radial gradient with constant slope out to 4 R e .
Pipe3D stellar and gaseous velocity dispersions for CALIFA Galaxies
Monthly Notices of the Royal Astronomical Society, 2018
We present tables of velocity dispersions derived from CALIFA V1200 datacubes using Pipe3D. Four different dispersions are extracted from emission (ionized gas) or absorption (stellar) spectra, with two spatial apertures (5 and 30). Stellar and ionized gas dispersions are not interchangeable and we determine their distinguishing features. We also compare these dispersions with literature values and construct sample scaling relations to further assess their applicability. We consider revised velocity-based scaling relations using the virial velocity parameter S 2 K = KV 2 rot + σ 2 constructed with each of our dispersions. Our search for the strongest linear correlation between S K and i-band absolute magnitudes favors the common K ∼ 0.5, though the range 0.3-0.8 is statistically acceptable. The reduction of scatter in our best stellar mass-virial velocity relations over that of a classic luminosity-velocity relation is minimal; this may however reflect the dominance of massive spirals in our sample.
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.