Rubén J. Díaz

Extreme galactic wind and Wolf—Rayet features in infrared mergers and infrared quasi-stellar objects

We report -as a part of a long-term study of mergers and IR QSOs- detailed spectroscopic evidences for outflow (OF) and/or Wolf Rayet features in: (i) low velocity OF in the ongoing mergers NGC 4038/39 and IRAS 23128-5919; (ii) extreme velocity OF (EVOF) in the QSOs IRAS 01003-2238 and IRAS 13218+0552; (iii) OF and EVOF in a complete sample of ultra-luminous IR galaxies/QSOs (The IRAS 1 Jy MKO-KPNO Survey, of 118 objects). We found EVOF in IRAS 11119+3257, 14394+5332, 15130+1958 and 15462-0450. The OF components detected in these objects were mainly associated to starburst processes: i.e., to galactic-winds generated in multiple type II SN explosions and massive stars. The EVOF were detected in objects with strong starburst plus obscured IR QSOs; which suggest that interaction of both processes could generate EVOF. In addition, we analyze the presence of Wolf Rayet features in the large sample of Bright PG-QSOs (Boroson and Green 1992), and nearby mergers and galactic-wind galaxies. We found clear WR features in the Fe II QSOs (type I): PG 1244+026, 1444+407, 1448+273, 1535+547; and in the IR merger Arp 220. HST archive images of IR+BAL QSOs show in practically all of these objectsarc or shellfeatures probably associated to galactic-winds (i.e., to multiple type II SN explosions) and/or merger processes. Finally, we discuss the presence of extreme starburst and galactic wind as a possible evolutive link between IR merger and IR QSOs; where the relation between mergers and extreme starburst (with powerful galactic-winds) plays in important role, in the evolution of galaxies.

Kinematics of the Central Regions of NGC 1672

Resumen en: We present two-dimensional spectroscopy and broad band imaging of the LINER galaxy NGC 1672. The velocity field and morphology of the central 2kpc indica...

Hidden trigger for the giant starburst arc in M83

The huge star formation events that occur at some galactic centers do not provide enough clues as to their origin, since the morphological signatures of the triggering mechanism are smeared out in the timescale of a few orbital revolutions of the galaxy core. Our high spatial resolution three-dimensional near-infrared spectroscopy for the first time reveals that a previously known hidden mass concentration is located exactly at the youngest end of a giant star-forming arc. This location, the inferred average cluster ages, and the dynamical times clearly indicate that the interloper has left behind a spur of violent star formation in M83, in a transient event lasting less than one orbital revolution. The study of the origin (bar funneling or cannibalized satellite) and fate (black hole merging or giant stellar cluster) of this system could provide clues to the question of core growing and morphological evolution in grand-design spiral galaxies. In particular, our TreeSPH numerical modeling suggests that the two nuclei could coalesce, forming a single massive core in about 60 million years or less. This work is based on observations made at the Gemini South Telescope.

Double Nucleus in M83

M83 is one of the nearest galaxies with enhanced nuclear star formation, and it presents one of the best opportunities to study the kinematics and physical properties of a circumnuclear starburst. Our three-dimensional spectroscopy data in the R band confirm the presence of a secondary nucleus or mass concentration (previously suggested by Thatte and coworkers). We determine the position of this hidden nucleus, which would be more massive than the visible one and was not detected in the optical Hubble Space Telescope images due, probably, to the strong dust extinction. Using a Keplerian approximation, we estimated for the optical nucleus a mass of (5.0 ± 0.8) × 106 M⊙/ sin i (r < 15), and for the hidden nucleus, located 4 ± 1 to the northwest (position angle of 271° ± 15°) of the optical nucleus, a mass of (1.00 ± 0.08) × 107 M⊙/ sin i (r < 15). The emission-line ratio map also unveils the presence of a second circumnuclear ring structure, previously discovered by IR imaging (Elmegreen and coworkers). The data allow us to resolve the behavior of the interstellar medium inside the circumnuclear ring and around the binary mass concentration.

CATALOG OF DOUBLE NUCLEUS DISK GALAXIES

We have compiled a catalog of disk galaxies that have a double nucleus, through systematic examination of existing catalogs and publications. The Catalog of Double Nucleus Disk Galaxies includes 107 objects, together with their basic data. The aim of the catalog is to provide a more systematic and homogeneous basis for the study of the relevance of galaxy interactions and minor mergers in the formation of these double nuclei. We have also investigated possible correlations between geometric and photometric parameters of the double nuclei and their host galaxies. The preliminary results indicate the presence of several significant correlations that should be considered in any theoretical scenario describing minor mergers and disk galaxy evolution.

Multiband Optical Polarimetry of the BL Lacertae Object PKS 2155–304: Intranight and Long-Term Variability

The polarized and total flux of the BL Lac object PKS 2155-304 were monitored intensively and simultaneously in the optical UBVRI bands with the Turin photopolarimeter at the CASLEO 2.15 m telescope during four campaigns in 1998 June, August, and November and 1999 August. The effective observation time amounted to ~47 hr. PKS 2155-304 showed a linear polarization percentage (P) usually ranging between 3% and 7% and a polarization position angle (P.A.) mainly between 70° and 120°. The highest temporal resolution of our observations, 15 minutes, is unprecedented for polarimetric monitoring of this source and has allowed us to detect amplitude variations of the linear polarization percentage from 6% to 7.5% in timescales of hours. In some nights the polarization percentage seems to increase toward shorter wavelengths; however, the polarized spectrum does not vary significantly with time. The most remarkable variability event occurred on 1998 June 18, when the degree of linear polarization decreased by more than a factor 2 in 1 day in all bands, while the P.A. rotated by 90°. This is consistent with the presence of two emission components, of different polarization degree and position angle. Intranight variability of P and P.A. can be interpreted with small-amplitude physical or geometrical changes within the jet. Measurements of the circular polarization over time intervals of days set upper limits of 0.2%. Simultaneous photometry taken with the Turin Photopolarimeter and with a CCD camera at Cordoba Astronomical Observatory did not show light variations correlated with those of the linearly polarized flux.

NGC 1566: Spectroscopy of a symmetric system with Seyfert nucleus

The central region and main body of the very symmetrical galaxy NGC 1566 were observed and studied spectropho- tometrically and kinematically. We found that: a) the total masses derived from the Satoh model fitted to the rotation curve, and from the global Hi radial velocity profile, are coincident: 2 10 11 M, which implies the presence of two galactic subsystems without the need for a massive halo; b) from the rotation curve of the fitted model an outflow motion at the bar tips is confirmed (V 40 km s 1 ); c) the observed non-circular motions in some regions with significant blue shifts (V 60 km s 1 ) would represent inflows of gas to the nucleus; d) the fitted pattern speed at (23 2) km s 1 kpc 1 allows one to explain the radial positions of the inner ring, the star formation ridge of the arms, and the ring at the main disk outer edge, as result of dynamical resonances; e) the nucleus was in a stage of Seyfert 1.8 and in a low level of activity during observations; f) nuclear and inner rings were detected; there is also evidence of a ring at the main disk outer edge; g) some emission regions in the arms have H fluxes higher than in the nucleus; h) the star bursts in the ring at the bar end radius would be younger than in the arms; i) the H emission appears to be correlated with the thermal component of the continuum radiation and with the molecular gas over the whole galaxy.

Circumnuclear Structures in the Interacting Seyfert Galaxy NGC 1241: Kinematics and Optical/Infrared Morphology

We studied the spiral pattern in the inner 65 (1 = 257 pc) central regions of the interacting active nucleus galaxy NGC 1241 using Gemini North Telescope high-resolution Ks- and J-band images and Hubble Space Telescope (HST) Paα and H- and (V + R)-band images with high resolution in the range from ~01 to ~03 along with intermediate to large-scale spectroscopy using the Multifunction Spectrograph at the Cordoba Observatory in Argentina. Our analysis of Paα emission images revealed a faint two-armed leading spiral pattern ending in the 56 × 34 clumpy ring discovered by Boker and coworkers, harboring a 16 long barlike structure almost perpendicular to the large-scale bar of NGC 1241. When we applied two-dimensional Fourier analysis at circumnuclear scales, we found that a two-arm trailing mode was dominant in Ks- and J-band images while the (V + R)-band images showed more complex structural features with a strong one-armed trailing mode. One-dimensional Fourier analysis showed a corotation (CR) located outward from the edge of the Paα bar. Our kinematics data gave an angular speed ΩCN of 350 ± 50 km s-1 kpc-1 for the trailing mode pattern. The rotation curve showed that the circumnuclear ring is located just inside the large-scale pattern inner Lindblad resonance (ILR), which has a radius of about r ~ 1 kpc. We also found, within the uncertainties present in such measurements, that the outer Lindblad resonance (OLR) of the circumnuclear pattern is coincident with the large-scale pattern ILR, indicating a possible connection between circumnuclear and global dynamics. Nevertheless, the estimated high molecular gas fraction (≥13%) and the inner pattern high angular speed at the central region of NGC 1241 point to a nuclear bar formation via self-gravitational instability.

Spectroscopic properties and dynamical evolution of the merging system AM 1003-435

Aims. We study the system AM 1003-435, which is composed of two strong interacting galaxies. Methods. We obtained long-slit optical spectra of twelve zones of the system, and performed numerical simulations of the encounter between the components following the evolution of their stellar and gaseous contents. Results. The spectrum of the NW nucleus is typical of a starburst, while that of the SE one shows weak emission lines. The highest values of the oxygen and nitrogen abundances are at the NW nucleus. Its derived Hα and Hα + [N II] equivalent widths indicate very intense star formation, in accord to its starburst nature. Indicative ages of the starbursts in the nuclei were obtained. The morphological types of both components derived from their spectral characteristics are in agreement with previous determinations based on photometric parameters. About 70% of the measured Hα luminosity would correspond to the NW component contribution. The IR luminosity of the system is not high (LIR < 10 11 L� ). The estimated star formation rate for AM 1003-435 indicates that its activity is also moderate. The IR radiation, if it has the same origin as the Hα emission, would arise mostly from the NW component. The resulting abundances, burst ages, and masses suggest that the starburst in the SE component, the minor one, started earlier than that of the NW one, and did so in a medium poorer in weighted elements. On the other hand, from a set of N-body simulations of the encounter between both components it was found the time of the perigalacticum, to be comparable to the burst age derived for the SE component, and the star formation in both galaxies would have begun after the perigalacticum. It was also estimated that the central bodies will merge in about 1 Gyr.

GeMS, the path toward AO facility

GeMS, the Gemini South MCAO System, has now been in regular operation since mid-2013 with the imager instrument GSAOI. We review the performance obtained during this past year as well as some of its current limitations. While in operation, GeMS is still evolving to push them back and is currently in the path of receiving two major upgrades which will allow new exciting science cases: a new natural guide star wavefront sensor called NGS2 and a replacement of the current 50W laser. We are also actively moving along the path of further deeper integration with the future AO-fed instruments, we present our first preliminary results of astrometric and spectrometric calibrations with diverse Gemini instruments using an internal calibration source. We finally report our efforts to make GeMS a more robust instrument with the integration of a vibration rejection feature and a more user-friendly AO system as well with advanced gain optimization automatization.