Near infrared imaging spectroscopy of NGC1275

We present H and K band imaging spectroscopy of the core regions of the cD/AGN galaxy NGC1275. The spectra, including lines from H2, H, 12CO bandheads, [FeII], and [FeIII], are exploited to constrain the star formation and excitation mechanisms in the galaxy's nucleus. The near-infrared properties can largely be accounted for by ionized gas in the NLR, dense molecular gas, and hot dust concentrated near the active nucleus of NGC1275. The strong and compact H2 emission is mostly from circumnuclear gas excited by the AGN and not from the cooling flow. The extended emission of latetype stars is diluted in the center by the thermal emission of hot dust.Comment: 16 pages, LaTex, 15 gif figures, aa.cls required, accepted for A&A, high resolution images at http://astro1.ws.ba.dlr.d

A new era of spectroscopy: SINFONI, NIR integral field spectroscopy at the diffraction limit of an 8m telescope

SINFONI, the SINgle Faint Object Near-infrared Investigation, is an instrument for the Very Large Telescope (VLT), which will start its operation mid 2002 and allow for the first time near infrared (NIR) integral field spectroscopy at the diffraction limit of an 8-m telescope. SINFONI is the combination of two state-of-the art instruments, the integral field spectrometer SPIFFI, built by the Max-Planck-Institut fuer extraterrestrische Physik (MPE), and the adaptive optics (AO) system MACAO, built by the European Southern Observatory (ESO). It will allow a unique type of observations by delivering simultaneously high spatial resolution (pixel sizes 0.025arcsec to 0.25arcsec) and a moderate spectral resolution (R~2000 to R~4500), where the higher spectral resolution mode will allow for software OH suppression. This opens new prospects for astronomy.Comment: 9 pages, 4 figures, to appear in SPIE proceedings "Astronomical Telescopes and Instrumentation 2000". More recent sensitivity estimates are available at http://www.mpe.mpg.de/www_ir/ir_instruments/sinfoni/spiffi.ht

The Discovery of Quasisoft and Supersoft Sources in External Galaxies

We apply a uniform procedure to select very soft sources from point sources observed by Chandra in 4 galaxies. This sample includes one elliptical galaxy (NGC 4967), 2 face-on spirals (M101 and M83), and an interacting galaxy (M51). We have found very soft X-ray sources (VSSs) in every galaxy. Some of these fit the criteria for canonical supersoft sources (SSSs), while others are somewhat harder. These latter have characteristic values of kT < 300 eV; we refer to them as quasisoft sources (QSSs). We found a combined total of 149 VSSs in the 4 galaxies we considered; 77 were SSSs and 72 were QSSs. (See the paper for the original long abstract)Comment: 20 pages, 6 figures. Accepted for publication in Ap

Reconstructing pedigrees: some identifiability questions for a recombination-mutation model

Pedigrees are directed acyclic graphs that represent ancestral relationships between individuals in a population. Based on a schematic recombination process, we describe two simple Markov models for sequences evolving on pedigrees - Model R (recombinations without mutations) and Model RM (recombinations with mutations). For these models, we ask an identifiability question: is it possible to construct a pedigree from the joint probability distribution of extant sequences? We present partial identifiability results for general pedigrees: we show that when the crossover probabilities are sufficiently small, certain spanning subgraph sequences can be counted from the joint distribution of extant sequences. We demonstrate how pedigrees that earlier seemed difficult to distinguish are distinguished by counting their spanning subgraph sequences.Comment: 40 pages, 9 figure

Stellar Dynamics and the implications on the merger evolution in NGC6240

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 1.6arcsec 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 ~2x10^7 years ago, possibly by the most recent perigalactic approach. Strong feedback effects of a superwind and supernovae are responsible for a short duration burst (~5x10^6 years) which 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 (H_2, 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 r^1/4-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.Comment: 34 pages, 11 figures, using AASTEX 5.0rc3.1, paper submitted to the Astrophysical Journal, revised versio

The Origin of the Young Stars in the Nucleus of M31

The triple nucleus of M31 consists of a population of old red stars in an eccentric disk (P1 and P2) and another population of younger A stars in a circular disk (P3) around M31's central supermassive black hole (SMBH). We argue that P1 and P2 determine the maximal radial extent of the younger A star population and provide the gas that fueled the starburst that generated P3. The eccentric stellar disk creates an $m=1$ non-axisymmetric perturbation to the potential. This perturbed potential drives gas into the inner parsec around the SMBH, if the pattern speed of the eccentric stellar disk is $\Omega_p \lesssim 3-10 {\rm km s^{-1} pc^{-1}}$. We show that stellar mass loss from P1 and P2 is sufficient to create a gravitationally unstable gaseous disk of \sim 10^5\Msun every $0.1-1$ Gyrs, consistent with the 200 Myr age of P3. Similar processes may act in other systems to produce very compact nuclear starbursts.Comment: 10 pages, 7 figures, accepted by ApJ, changes made from referee suggestion

Young Clusters in the Nuclear Starburst of M 83

We present a photometric catalog of 45 massive star clusters in the nuclear starburst of M 83 (NGC 5236), observed with the Hubble Space Telescope WFPC2, in both broad-band (F300W, F547M, and F814W) and narrow-band (F656N and F487N) filters. By comparing the photometry to theoretical population synthesis models, we estimate the age and mass of each cluster. We find that over 75% of the star clusters more massive than 2*10^4 Msun in the central 300 pc of M 83 are less than 10 Myr old. Among the clusters younger than 10 Myr and more massive than 5*10^3 Msun, 70% are between 5 and 7 Myr old. We list an additional 330 clusters that are detected in our F300W images, but not in the shallower F547M and F814W images. The clusters are distributed throughout a semicircular annulus that identifies the active region in the galaxy core, between 50 and 130 pc from the optical center of M 83. Clusters younger than 5 Myr are preferentially found along the perimeter of the semicircular annulus. We suggest that the 5-7 Myr population has evacuated much of the interstellar material from the active ringlet region, and that star formation is continuing along the edges of the region.Comment: 40 pages, 13 figures, accepted to ApJ

Evaluation of endoscopic vein extraction on structural and functional viability of saphenous vein endothelium

<p>Abstract</p> <p>Objectives</p> <p>Endothelial injury during harvest influences graft patency post CABG. We have previously shown that endoscopic harvest causes structural and functional damage to the saphenous vein (SV) endothelium. However, causes of such injury may depend on the extraction technique. In order to assess this supposition, we evaluated the effect of VirtuoSaph endoscopic SV harvesting technique (VsEVH) on structural and functional viability of SV endothelium using multiphoton imaging, biochemical and immunofluorescence assays.</p> <p>Methods</p> <p>Nineteen patients scheduled for CABG were prospectively identified. Each underwent VsEVH for one portion and "No-touch" open SV harvesting (OSVH) for another portion of the SV. A two cm segment from each portion was immersed in GALA conduit preservation solution and transported overnight to our lab for processing. The segments were labeled with fluorescent markers to quantify cell viability, calcium mobilization and generation of nitric oxide. Morphology, expression, localization and stability of endothelial caveolin, eNOS, von Willebrand factor and cadherin were evaluated using immunofluorescence, Western blot and multiphoton microscopy (MPM).</p> <p>Results</p> <p>Morphological, biochemical and immunofluorescence parameters of viability, structure and function were well preserved in VsEVH group as in OSVH group. However, tonic eNOS activity, agonist-dependent calcium mobilization and nitric oxide production were partially attenuated in the VsEVH group.</p> <p>Conclusions</p> <p>This study indicates that VirtuoSaph endoscopic SV harvesting technique preserves the structural and functional viability of SV endothelium, but may differentially attenuate the vasomotor function of the saphenous vein graft.</p> <p>Ultramini-Abstract</p> <p>Endoscopic extraction preserved the structure and function, but attenuated the calcium mobilization and nitric oxide generation in human SV endothelium.</p

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 infrared spectra in more than 1000 image points of a two dimensional 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

Galaxies in Southern Bright Star Fields I. Near-infrared imaging

As a prerequisite for cosmological studies using adaptive optics techniques, we have begun to identify and characterize faint sources in the vicinity of bright stars at high Galactic latitudes. The initial phase of this work has been a program of K_s imaging conducted with SOFI at the ESO NTT. From observations of 42 southern fields evenly divided between the spring and autumn skies, we have identified 391 additional stars and 1589 galaxies lying at separations 60" from candidate guide stars in the magnitude range 9.0 R 12.4. When analyzed as a "discrete deep field" with 131 arcmin^2 area, our dataset gives galaxy number counts that agree with those derived previously over the range 16 K_s 20.5. This consistency indicates that in the aggregate, our fields should be suitable for future statistical studies. We provide our source catalogue as a resource for users of large telescopes in the southern hemisphere.Comment: 10 pages, 7 figures, accepted by A&A; Table 3 is available at http://www.rzg.mpg.de/~ajb/data.html pending upload to CD