Matthias Tecza

SINFONI: integral field spectroscopy at 50-milli-arcsecond resolution with the ESO VLT

SINFONI is an adaptive optics assisted near-infrared integral field spectrometer for the ESO VLT. The Adaptive OPtics Module (built by the ESO Adaptive Optics Group) is a 60-elements curvature-sensor based system, designed for operations with natural or sodium laser guide stars. The near-infrared integral field spectrometer SPIFFI (built by the Infrared Group of MPE) provides simultaneous spectroscopy of 32 x 32 spatial pixels, and a spectral resolving power of up to 3300. The adaptive optics module is in the phase of integration; the spectrometer is presented tested in the laboratory. We provide an overview of the project, with particular emphasis on the problems encountered in designing and building an adaptive optics assisted spectrometer.

A geometric determination of the distance to the Galactic center

We report new astrometric and spectroscopic observations of the star S2 orbiting the massive black hole in the Galactic center that were taken at the ESO VLT with the adaptive optics-assisted, near-IR camera NAOS/CONICA and the near-IR integral field spectrometer SPIFFI. We use these data to determine all the orbital parameters of the star with high precision, including the Sun-Galactic center distance, which is a key parameter for calibrating stellar standard candles and an important rung in the extragalactic distance ladder. Our deduced value of R0 = 7.94 ± 0.42 kpc is the most accurate primary distance measurement to the center of the Milky Way and has minimal systematic uncertainties of astrophysical origin. It is in excellent agreement with other recent determinations of R0.

Ultraluminous Infrared Mergers: Elliptical Galaxies in Formation?*

We report high-quality near-IR spectroscopy of 12 ultraluminous infrared galaxy mergers (ULIRGs). Our new VLT and Keck data provide ~05 resolution, stellar and gas kinematics of these galaxies, most of which are compact systems in the last merger stages. We confirm that ULIRG mergers are ellipticals in formation. Random motions dominate their stellar dynamics, but significant rotation is common. Gasdynamics and stellar dynamics are decoupled in most systems. ULIRGs fall on or near the fundamental plane of hot stellar systems, and especially on its less evolution-sensitive, reff-σ projection. The ULIRG velocity dispersion distribution, their location in the fundamental plane, and their distribution of vrot sin i/σ closely resemble those of intermediate-mass (~L*), elliptical galaxies with moderate rotation. As a group ULIRGs do not resemble giant ellipticals with large cores and little rotation. Our results are in good agreement with other recent studies indicating that disky ellipticals with compact cores or cusps can form through dissipative mergers of gas-rich disk galaxies while giant ellipticals with large cores have a different formation history.

Ultraluminous Infrared Galaxies: QSOs in Formation?

We present new near-infrared (NIR) Keck and Very Large Telescope (VLT) spectroscopic data on the stellar dynamics in late-stage, ultraluminous infrared galaxy (ULIRG) mergers. We now have information on the structural and kinematic properties of 18 ULIRGs, eight of which contain QSO-like active galactic nuclei (AGNs). The host properties (σ, reff, μeff, MK) of AGN-dominated and star formation dominated ULIRGs are similar. ULIRGs fall remarkably close to the fundamental plane of early-type galaxies. They populate a wide range of the plane, are on average similar to L* rotating ellipticals, but are well offset from giant ellipticals and optically/UV-bright, low-z QSOs/radio galaxies. ULIRGs and local QSOs/radio galaxies are very similar in their distributions of bolometric and extinction-corrected NIR luminosities, but ULIRGs have smaller effective radii and velocity dispersions than the local QSO/radio galaxy population. Hence, their host masses and inferred black hole masses are correspondingly smaller. The latter are more akin to those of local Seyfert galaxies. ULIRGs thus resemble local QSOs in their NIR and bolometric luminosities because they are (much more) efficiently forming stars and/or feeding their black holes, and not because they have QSO-like, very massive black holes. We conclude that ULIRGs as a class cannot evolve into optically bright QSOs. They will more likely become quiescent, moderate mass field ellipticals or, when active, might resemble the X-ray-bright, early-type galaxies that have recently been found by the Chandra observatory.

Gasdynamics in the Luminous Merger NGC 6240

We report 05 × 09 resolution, interferometric observations of the 1.3 mm CO J = 2 → 1 line in the infrared luminous galactic merger NGC 6240. About half of the CO flux is concentrated in a rotating but highly turbulent, thick disk structure centered between the two radio and near-infrared nuclei. A number of gas features connect this ~500 pc diameter central disk to larger scales. Throughout this region the molecular gas has local velocity widths which exceed 300 km s-1 FWHM and even reach FWZP line widths of 1000 km s-1 in a number of directions. The mass of the central gas concentration constitutes a significant fraction of the dynamical mass, Mgas(R ≤ 470 pc) ~ × 109 M☉ ~ Mdyn. We conclude that NGC 6240 is in an earlier merging stage than the prototypical ultraluminous galaxy, Arp 220. The interstellar gas in NGC 6240 is in the process of settling between the two progenitor stellar nuclei, is dissipating rapidly, and will likely form a central thin disk. In the next merger stage, NGC 6240 may well experience a major starburst like that observed in Arp 220.

The Nuclear Stellar Core, the Hot Dust Source, and the Location of the Nucleus of NGC 1068

We present new near-infrared speckle and adaptive optics imaging and integral field spectroscopy of the nuclear region of NGC 1068. Ninety-four percent of the K-band light in the central 1 originates from a ≤30 milliarcsecond diameter source whose position we determine to coincide within ±015 with the apex of the cone structure seen in the optical narrow emission lines, as well as the location of the flat spectrum radio component S1 and the 12 μm emission peak. We interpret the compact source as hot dust near the sublimation temperature within ~1 pc of the true nucleus of the galaxy. The remaining 6% of the light in the central 1 comes from a moderately extincted stellar core centered on the nuclear position and of intrinsic size ~50 pc. We show that this nuclear stellar core is probably 5-16 × 108 yr in age and contributes at least 7% of the total nuclear luminosity of ~1 × 1011 L☉.

Stellar Dynamics and the Implications on the Merger Evolution in NGC 6240

We report near-infrared integral field spectroscopy of the luminous merging galaxy NGC 6240. Stellar velocities show that the two K-band peaks separated by 16 are the central parts of inclined, rotating disk galaxies with equal mass bulges. The dynamical masses of the nuclei are much larger than the stellar mass derived from the K-band light, implying that the progenitor galaxies were galaxies with massive bulges. The K-band light is dominated by red supergiants formed in the two nuclei in starbursts, triggered ≈2 × 107 yr ago, possibly by the most recent perigalactic approach. Strong feedback effects of a superwind and supernovae are responsible for a short duration burst (≈5 × 106 yr) that is already decaying. The two galaxies form a prograde-retrograde rotating system and from the stellar velocity field it seems that one of the two interacting galaxies is subject to a prograde encounter. Between the stellar nuclei is a prominent peak of molecular gas (H2, CO). The stellar velocity dispersion peaks there indicating that the gas has formed a local, self-gravitating concentration decoupled from the stellar gravitational potential. NGC 6240 has previously been reported to fit the paradigm of an elliptical galaxy formed through the merger of two galaxies. This was based on the near-infrared light distribution, which follows a r1/4-law. Our data cast strong doubt on this conclusion: the system is by far not relaxed, rotation plays an important role, as does self-gravitating gas, and the near-infrared light is dominated by young stars.

SPIFFI Observations of the Starburst SMM J14011+0252:Already Old, Fat, and Rich by z = 2.565

Using the SPectrometer for Infrared Faint Field Imaging on the ESO Very Large Telescope, we have obtained J-, H-, and K-band integral field spectroscopy of the luminous submillimeter galaxy SMM J140110252. z p 2.565 A global spectrum reveals the brighter of this spatially resolved system’s two components as an intense starburst that is remarkably old, massive, and metal-rich for the early epoch at which it is observed. We see a strong Balmer break implying a ≥100 Myr timescale for continuous star formation as well as nebular emission-line ratios implying a supersolar oxygen abundance on large spatial scales. Overall, the system is rapidly converting a large baryonic mass into stars over the course of only a few hundred megayears. Our study thus adds new arguments to the growing evidence that submillimeter galaxies are more massive than Lyman break galaxies and more numerous at high redshift than predicted by current semianalytic models of galaxy evolution. Subject headings: galaxies: abundances — galaxies: evolution — galaxies: formation

Imaging the universe in 3D with the VLT: the next-generation field spectrometer SPIFFI

We present SPIFFI, the integral field spectrometer for the VLT. This instrument allows simultaneous observation of IR spectra in more than 1000 image points of a 2D field. With its set of four gratings and a pixel scale that can be varied by a factor of ten, SPIFFI provides high flexibility, and at the same time offers the unique possibility of diffraction limited imaging spectroscopy at an 8m-class telescope, when fed by the adaptive optics system MACAO. We outline the scientific drivers for building such an instrument, the concept of image slicing, the optical design, and the implementation of SPIFFI.

ROGUE - the Rapid Off-axis GUider Experiment

Near infrared imaging spectroscopy at spatial resolutions of 0.5 arc seconds will fundamentally change our understanding of active galactic nuclei. This long desired capability has been achieved for the first time by the latest generation of MPE instruments, ROGUE and 3D. ROGUE, the rapid off-axis guider experiment, is a low order adaptive optics system performing tip-tilt correction in the near infrared using natural guide stars. Three-dimensional is the MPE near infrared imaging spectrometer capable of simultaneous imaging and spectroscopy of the entire H and K atmospheric windows. ROGUE is capable of tip-tilt correction at 40 Hz in a 4 arc-minute diameter isokinetic patch using natural guide stars as faint as 18th magnitude. We discuss the design of the instrument, present the first astronomical results, and outline future efforts to incorporate variable image scales.