Publications by Michele Cappellari

The second generation VLT instrument MUSE: Science drivers and instrument design

P SOC PHOTO-OPT INS 5492 (2004) 1145-1149

R Bacon, S Bauer, R Bower, S Cabrit, M Cappellari, M Carollo, FO Combes, R Davies, B Delabre, H Dekker, J Devriendt, S Djidel, M Duchateau, JP Dubois, E Emsellem, P Ferruit, M Franx, G Gilmore, B Guiderdoni, F Henault, N Hubin, B Jungwiert, A Kelz, M Le Louarn, I Lewis, JL Lizon, R Mc Dermid, S Morris, U Laux, O Le Fevre, B Lantz, S Lilly, J Lynn, L Pasquin, A Pecontal, PPD Popovic, A Quirrenbach, R Reiss, M Roth, M Steinmetz, R Stuik, L Wisotzki, T de Zeeuw

The Multi Unit Spectroscopic Explorer (MUSE) is a second generation VLT panoramic integral-field spectrograph operating in the visible wavelength range. MUSE has a field of 1x1 arcmin(2) sampled at 0.20.2 arcsec(2) and is assisted by a ground layer adaptive optics system using four laser guide stars. The simultaneous spectral range is 0.465-0.93 mum, at a resolution of Rsimilar to3000. MUSE couples the discovery potential of a large imaging device to the measuring capabilities of a high-quality spectrograph, while taking advantage of the increased spatial resolution provided by adaptive optics. This makes MUSE a unique and tremendously powerful instrument for discovering and characterizing objects that lie beyond the reach of even the deepest imaging surveys. MUSE has also a high spatial resolution mode with 7.5x7.5 arcsec(2) field of view sampled at 25 milli-arcsec. In this mode MUSE should be able to get diffraction limited data-cube in the 0.6-1 mum wavelength range. Although MUSE design has been optimized for the study of galaxy formation and evolution, it has a wide range of possible applications; e.g. monitoring of outer planets atmosphere, young stellar objects environment, supermassive black holes and active nuclei in nearby galaxies or massive spectroscopic survey of stellar fields.

Orbital structure of triaxial galaxies

IAU SYMP (2004) 179-180

G van de Ven, E Verolme, M Cappellari, T de Zeeuw

We have developed a method to construct realistic triaxial dynamical models for elliptical galaxies, allowing us to derive best-fitting parameters, such as the mass-to-light ratio and the black hole mass, and to study the orbital structure. We use triaxial theoretical Abel models to investigate the robustness of the method.

Adaptive spatial binning of integral-field spectroscopic data using Voronoi tessellations

Monthly Notices of the Royal Astronomical Society 342 (2003) 345-354

M Cappellari, Copin, Yannick

A SAURON view of galaxies

LECT NOTES PHYS 626 (2003) 279-285

EK Verolme, M Cappellari, G van de Ven, PT de Zeeuw, R Bacon, M Bureau, Y Copin, RL Davies, E Emsellem, H Kuntschner, R McDermid, BW Miller, RF Peletier

We have measured the two-dimensional kinematics and line-strength distributions of 72 representative nearby early-type galaxies, out to approximately one effective radius, with our panoramic integral-field spectrograph SAURON. The resulting maps reveal a rich variety in kinematical structures and linestrength distributions, indicating that early-type galaxies are more complex systems than often assumed. We are building detailed dynamical models for these galaxies, to derive their intrinsic shape and dynamical structure, and to determine the mass of the supermassive central black hole. Here we focus on two examples, the compact elliptical M32 and the E3 galaxy NGC4365. These objects represent two extreme cases: M32 has very regular kinematics which can be represented accurately by an axisymmetric model in which all stars rotate around the short axis, while NGC4365 is a triaxial galaxy with a prominent kinematically decoupled core, with an inner core that rotates about an axis that is nearly perpendicular to the rotation axis of the main body of the galaxy. Our dynamical models for these objects demonstrate that two-dimensional observations are essential for deriving the intrinsic orbital structure and dark matter content of galaxies.

SAURON: Observations of E/S0/SA galaxies

REV MEX AST ASTR 17 (2003) 199-199

H Kuntschner, R Bacon, M Bureau, M Cappellari, Y Copin, RL Davies, E Emsellem, BW Miller, R McDermid, RF Peletier, EK Verolme, PT de Zeeuw

We present results from a new and unique integral-field spectrograph, SAURON. It has a large field of view and high throughput and is primarily built for the study of stellar & gaseous kinematics and stellar populations in galaxies. Its aim is to carry out a systematic survey of the velocity fields, velocity dispersions, and line-strength distributions of nearby ellipticals, lenticular galaxies and spiral bulges.

A SAURON study of M32: measuring the intrinsic flattening and the central black hole mass


EK Verolme, M Cappellari, Y Copin, RP van der Marel, R Bacon, M Bureau, RL Davies, BM Miller, PT de Zeeuw

Two-dimensional kinematics and stellar populations of early-type galaxies: First results from the SAURON survey

ASTR SOC P 282 (2002) 179-188

R Bacon, M Bureau, M Cappellari, Y Copin, R Davies, E Emsellem, H Kuntschner, R McDermid, B Miller, R Peletier, E Verolme, T de Zeeuw

We present the SAURON project, which is aimed at studying the morphology, two-dimensional kinematics and stellar populations of a representative sample of elliptical galaxies and spiral bulges.SAURON, a dedicated integral-field spectrograph that is optimized for observations and has high throughput, was built in Lyon and is now operated at the WHT 4.2m telescope. At present, we have ob served approximately two thirds of the seventy-two sample galaxies with SAURON. A comparison with published long-slit measurements demonstrates that the SAURON-data are of equal or better quality, and provides full two-dimensional coverage. The velocity and velocity dispersion fields exhibit a large variety of morphologies: from simple rotating systems to cylindrical, disky and triaxial velocity fields, bars and decoupled cores. Most of these kinematical signatures do not have counterparts in the light distribution. While some galaxies are consistent with axisymmetry, most Are more complex systems than assumed previously. This suggests that the kinematical properties of nearby E/S0 galaxies do not agree with the often assumed simplistic two-family model, in which the giant non-rotating triaxial ellipticals are opposed to the fast-rotating axisymmetric faint ellipticals and S0s.

The Counterrotating Core and the Black Hole Mass of IC 1459

Astrophysical Journal 578 (2002) 787-805

M Cappellari, van der Marel, R. P., Verdoes Kleijn, G. A., Verolme, E. K.

SAURON observations of disks in spheroids

ASTR SOC P 282 (2002) 208-215

M Bureau, R Bacon, E Emsellem, M Cappellari, EK Verolme, PT de Zeeuw, Y Copin, RL Davies, R McDermid, H Kuntschner, BW Miller, RF Peletier

The panoramic integral-field spectrograph SAURON is currently being used to map the stellar kinematics, gaseous kinematics, and stellar populations of a large number of early-type galaxies and bulges. Here, we describe SAURON observations of cold stellar disks embedded in spheroids (NGC 3384, NGC 4459, NGC 4526), we illustrate the kinematics and ionization state of large-scale gaseous disks (NGC 4278, NGC 7742), and we show preliminary comparisons of SAURON data with barred galaxy N-body simulations (NGC 3623).

Probing the stellar populations of early-type galaxies: the SAURON survey

ASTR SOC P 282 (2002) 189-200

E Emsellem, R Davies, R McDermid, H Kuntschner, R Peletier, R Bacon, M Bureau, M Cappellari, Y Copin, B Miller, E Verolme, T de Zeeuw

The SAURON project will deliver two-dimensional spectroscopic data of a sample of nearby early-type galaxies with unprecedented quality. In this paper, we focus on the mapping of their stellar populations using the SAURON data, and present some preliminary results on a few prototypical cases.

SAURON: An innovative look at early-type galaxies

ASTR SOC P 273 (2002) 53-62

M Bureau, M Cappellari, Y Copin, EK Verolme, PT de Zeeuw, R Bacon, E Emsellem, RL Davies, H Kuntschner, R McDermid, BW Miller, RF Peletier

A summary of the SAURON project and its current status is presented. SAURON is a panoramic integral-field spectrograph designed to study the stellar kinematics, gaseous kinematics, and stellar populations of spheroids. Here, the sample of galaxies and its properties axe described. The instrument is detailed and its capabilities illustrated through observational examples. These includes results on the structure of central stellar disks, the kinematics and ionization state of gaseous disks, and the stellar populations of galaxies with decoupled cores.

Position-velocity diagrams of ionized gas in the inner regions of disk galaxies


JG Funes, EM Corsini, M Cappellari, A Pizzella, JCV Beltran, C Scarlata, F Bertola

Adaptive spatial binning of 2D spectra and images using Voronoi Tessellations

ASTR SOC P 282 (2002) 515-522

M Cappellari, Y Copin

We present new techniques to perform adaptive spatial binning of two-dimensional (2D) data to reach a chosen constant signal-to-noise ratio per bin. These methods are required particularly for the proper analysis of Integral Field Spectrograph (IFS) observations, but can also be used for standard photometric imagery. Various schemes axe tested and compared using data obtained with the panoramic IFS SAURON.

Efficient multi-Gaussian expansion of galaxies


M Cappellari

Position-velocity diagrams in the inner regions of disk galaxies

ASTR SOC P 230 (2001) 277-278

JG Funes, A Pizzella, EM Corsini, M Cappellari, MC Scarlata, F Bertola, JCV Beltran

The cuspy liner nucleus of the S0/A galaxy NGC 2681

ASTROPHYSICAL JOURNAL 551 (2001) 197-205

M Cappellari, F Bertola, D Burstein, LM Buson, L Greggio, A Renzini

The orthogonal bulge-disc decoupling in NGC 4698

ASTROPHYS SPACE SCI 276 (2001) 467-473

M Sarzi, F Bertola, M Cappellari, EM Corsini, JG Funes, A Pizzella, JCV Beltran

The R-band isophotal map of the Sa galaxy NGC 4698 shows that the inner region of the bulge is elongated perpendicularly to the major axis of the disc. At the same time a central stellar velocity gradient is found along the minor axis of the disc. The same properties have also been recognized in the Sa galaxy NGC 4672. This remarkable geometric and kinematic decoupling is a direct indication that a second event occurred in the history of these galaxies suggesting that acquisition phenomena could play a primary role in the formation of early-type spirals.

The cuspy liner nucleus of the S0/A galaxy NGC 2681

Astrophysical Journal 551 (2001) 197-205

M Cappellari, F Bertola, D Burstein, LM Buson, L Greggio, A Renzini

The nucleus of the bulge-dominated, multiply barred S0/a galaxy NGC 2681 is studied in detail using the high-resolution Hubble Space Telescope Faint Object Camera (FOC), Near-Infrared Camera and Multiobject Spectrometer (NICMOS) imaging, and the Faint Object Spectrograph (FOS). The ionized gas central velocity dispersion is found to increase by a factor ≈2 when narrowing the aperture from R ≈ 1″.5 (ground) to R ≈ 0″.1 (FOS). Dynamical modeling of these velocity dispersions suggests that NGC 2681 does host a supermassive black hole (BH) for which one can estimate a firm mass upper limit MBH ≲ 6 × 107 M⊙. This upper limit is consistent with the relation between the central BH mass and velocity dispersion MBH - σ known for other galaxies. The emission-line ratios place the nucleus of NGC 2681 among LINERs. It is likely that the emission-line region comes from a rather mild, but steady, feeding of gas to the central BH in this galaxy. The inner stellar population lacks any measurable color gradient (to a radius of 0.6 kpc) from the infrared to the ultraviolet, consistently with FOC, FOS, and IUE data, all indicating that this system underwent a starburst ≈1 Gyr ago that encompassed its whole interior, down to its very center. The most likely source of such a widely distributed starburst is the dumping of tidally extruded gas from a galaxy neighbor. If so, then NGC 2681 can be considered as the older brother of M82, seen face-on as opposed to the edge-on view we have for M82.

An orthogonal stellar disk in the nucleus of NGC 4698

ASTR SOC P 230 (2001) 163-164

MC Scarlata, F Bertola, M Cappellari, M Sarzi, EM Corsini, A Pizzella

Nuclear Mass Concentrations in Galaxies

Publications of the Astronomical Society of the Pacific IOP Publishing 113 (2001) 769-769

M Cappellari