SAURON Observations of Disks in Early-Type Galaxies

We briefly describe the SAURON project, aimed at determining the intrinsic shape and internal dynamics of spheroids. We focus here on the ability of SAURON to identify gaseous and stellar disks and to measure their morphology and kinematics. We illustrate some of our results with complete maps of NGC3377, NGC3623, and NGC4365.Comment: 4 pages, 4 figures (newpasp.sty). To appear in ASP Conf. Series "Galaxy Disks and Disk Galaxies", eds. J.G. Funes S.J. & E.M. Corsini. Version with full resolution images available at http://www.strw.leidenuniv.nl/~bureau/pub_list.htm

The GALEX/S4G UV-IR color-color diagram: Catching spiral galaxies away from the Blue Sequence

We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6$\mu$m photometry for > 2000 galaxies, available for 90% of the S4G sample. We find a very tight "GALEX Blue Sequence (GBS)" in the (FUV-NUV) versus (NUV-[3.6]) color-color diagram which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale ($\tau$) and a degeneracy between $\tau$ and dust reddening. The tightness of the GBS provides an unprecedented way of identifying star-forming galaxies and objects that are just evolving to (or from) what we call the "GALEX Green Valley (GGV)". At the red end of the GBS, at (NUV-[3.6]) > 5, we find a wider "GALEX Red Sequence (GRS)" mostly populated by E/S0 galaxies that has a perpendicular slope to that of the GBS and of the optical red sequence. We find no such dichotomy in terms of stellar mass (measured by $\rm{M}_{[3.6]}$), since both massive ($M_{\star} > 10^{11} M_{\odot}$) blue and red sequence galaxies are identified. The type that is proportionally more often found in the GGV are the S0-Sa's and most of these are located in high-density environments. We discuss evolutionary models of galaxies that show a rapid transition from the blue to the red sequence on timescale of $10^{8}$years.Comment: 7 pages, 4 figures, 1 table. Accepted for publication in ApJ

XSL: The X-Shooter Spectral Library

We are building a new spectral library with the X-Shooter instrument on ESO's VLT: XSL, the X-Shooter Spectral Library. We present our progress in building XSL, which covers the wavelength range from the near-UV to the near-IR with a resolution of R ~ 10000. At the time of writing we have collected spectra for nearly 240 stars. An important feature of XSL is that we have already collected spectra of more than 100 Asymptotic Giant Branch stars in the Galaxy and the Magellanic Clouds.Comment: 8 pages, 4 figures, to be published in the proceedings of the "GREAT-ESF Stellar Atmospheres in the Gaia Era Workshop", Brussels, Belgium, 23-24 June, 201

Supermassive black holes from OASIS and SAURON integral-field kinematics

Supermassive black holes are a key element in our understanding of how galaxies form. Most of the progress in this very active field of research is based on just ~30 determinations of black hole mass, accumulated over the past decade. We illustrate how integral-field spectroscopy, and in particular our OASIS modeling effort, can help improve the current situation.Comment: 4 pages, 2 figures, LaTeX. To appear in the proceedings of IAU Symposium 245 "Formation and Evolution of Galaxy Bulges", M. Bureau, E. Athanassoula, and B. Barbuy, ed

Fast and Slow Rotators: The build-up of the Red Sequence

Using the unique dataset obtained within the course of the SAURON project, a radically new view of the structure, dynamics and stellar populations of early-type galaxies has emerged. We show that galaxies come in two broad flavours (slow and fast rotators), depending on whether or not they exhibit clear large-scale rotation, as indicated via a robust measure of the specific angular momentum of baryons. This property is also linked with other physical characteristics of early-type galaxies, such as: the presence of dynamically decoupled cores, orbital structure and anisotropy, stellar populations and dark matter content. I here report on the observed link between this baryonic angular momentum and a mass sequence, and how this uniquely relates to the building of the red sequence via dissipative/dissipationless mergers and secular evolution.Comment: 4 pages, 1 figure. To appear in the Proceedings of IAU Symposium 245 "Formation and Evolution of Galaxy Bulges", Eds M. Bureau, E. Athanassoula, and B. Barbu

Galaxy mapping with the SAURON integral-field spectrograph: The star formation history of NGC 4365

We report the first wide-field mapping of the kinematics and stellar populations in the E3 galaxy NGC 4365. The velocity maps extend previous long-slit work. They show two independent kinematic subsystems: the central 300 x 700 pc rotates about the projected minor axis, and the main body of the galaxy, 3 x 4 kpc, rotates almost at right angles to this. The line-strength maps show that the metallicity of the stellar population decreases from a central value greater than solar, to one-half solar at a radius of 2 kpc. The decoupled core and main body of the galaxy have the same luminosity-weighted age, of ~14 Gyr, and the same elevated magnesium-to-iron ratio. The two kinematically distinct components have thus shared a common star formation history. We infer that the galaxy underwent a sequence of mergers associated with dissipative star formation that ended >12 Gyr ago. The misalignment between the photometric and kinematic axes of the main body is unambiguous evidence of triaxiality. The similarity of the stellar populations in the two components suggests that the observed kinematic structure has not changed substantially in 12 Gyr.Comment: 5 pages, accepted for publication in ApJ Letter

The SAURON project. II. Sample and early results

Early results are reported from the SAURON survey of the kinematics and stellar populations of a representative sample of nearby E, S0 and Sa galaxies. The survey is aimed at determining the intrinsic shape of the galaxies, their orbital structure, the mass-to-light ratio as a function of radius, the age and metallicity of the stellar populations, and the frequency of kinematically decoupled cores and nuclear black holes. The construction of the representative sample is described, and its properties are illustrated. A comparison with long-slit spectroscopic data establishes that the SAURON measurements are comparable to, or better than, the highest-quality determinations. Comparisons are presented for NGC 3384 and NGC 4365 where stellar velocities and velocity dispersions are determined to a precision of 6 km/s, and the h3 and h4 parameters of the line-of-sight velocity distribution to a precision of better than 0.02. Extraction of accurate gas emission-line intensities, velocities and line widths from the datacubes is illustrated for NGC 5813. Comparisons with published line-strengths for NGC 3384 and NGC 5813 reveal uncertainties of < 0.1 A on the measurements of the Hbeta, Mgb and Fe5270 indices. Integral-field mapping uniquely connects measurements of the kinematics and stellar populations to the galaxy morphology. The maps presented here illustrate the rich stellar kinematics, gaseous kinematics, and line-strength distributions of early-type galaxies. The results include the discovery of a thin, edge-on, disk in NGC 3623, confirm the axisymmetric shape of the central region of M32, illustrate the LINER nucleus and surrounding counter-rotating star-forming ring in NGC 7742, and suggest a uniform stellar population in the decoupled core galaxy NGC 5813.Comment: 20 pages, 17 figures. To be published in MNRAS. Version with full resolution images available at http://www.strw.leidenuniv.nl/~dynamics/Instruments/Sauron/pub_list.htm

The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs

The Coma cluster, Abell 1656, was the target of a HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in early 2007, the partially-completed survey still covers approximately 50% of the core high density region in Coma. Observations were performed for twenty-five fields with a total coverage area of 274 aremin(sup 2), and extend over a wide range of cluster-centric radii (approximately 1.75 Mpe or 1 deg). The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the south-west region of the cluster. In this paper we present SEXTRACTOR source catalogs generated from the processed images, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SEXTRACTOR Kron magnitudes based only on the measured source flux and its half-light radius. We have performed photometry for 76,000 objects that consist of roughly equal numbers of extended galaxies and unresolved objects. Approximately two-thirds of all detections are brighter than F814W=26.5 mag (AB), which corresponds to the 10sigma, point-source detection limit. We estimate that Coma members are 5-10% of the source detections, including a large population of compact objects (primarily GCs, but also cEs and UCDs), and a wide variety of extended galaxies from cD galaxies to dwarf low surface brightness galaxies. The initial data release for the HST-ACS Coma Treasury program was made available to the public in August 2008. The images and catalogs described in this study relate to our second data release

The SAURON project - III. Integral-field absorption-line kinematics of 48 elliptical and lenticular galaxies

We present the stellar kinematics of 48 representative elliptical and lenticular galaxies obtained with our custom-built integral-field spectrograph SAURON operating on the William Herschel Telescope. The data were homogeneously processed through a dedicated reduction and analysis pipeline. All resulting SAURON datacubes were spatially binned to a constant minimum signal-to-noise. We have measured the stellar kinematics with an optimized (penalized pixel-fitting) routine which fits the spectra in pixel space, via the use of optimal templates, and prevents the presence of emission lines to affect the measurements. We have thus generated maps of the mean stellar velocity, the velocity dispersion, and the Gauss-Hermite moments h3 and h4 of the line-of-sight velocity distributions. The maps extend to approximately one effective radius. Many objects display kinematic twists, kinematically decoupled components, central stellar disks, and other peculiarities, the nature of which will be discussed in future papers of this series.Comment: 23 pages, 18 figures. Accepted for publication in MNRAS. Version with full resolution images available at http://www.strw.leidenuniv.nl/sauron/papers/emsellem2004_sauron3.pd

The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs

The Coma cluster was the target of a HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in 2007, the partially completed survey still covers ~50% of the core high-density region in Coma. Observations were performed for 25 fields that extend over a wide range of cluster-centric radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the south-west region of the cluster. In this paper we present reprocessed images and SExtractor source catalogs for our survey fields, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SExtractor Kron magnitudes based only on the measured source flux and half-light radius. We have performed photometry for ~73,000 unique objects; one-half of our detections are brighter than the 10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight majority of objects (60%) are unresolved or only marginally resolved by ACS. We estimate that Coma members are 5-10% of all source detections, which consist of a large population of unresolved objects (primarily GCs but also UCDs) and a wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The red sequence of Coma member galaxies has a constant slope and dispersion across 9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma Treasury program was made available to the public in 2008 August. The images and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd