The nuclear source of the galactic wind in NGC 253

We present Brγ emission line kinematics of the nuclear region of NGC 253, recently known to host a strong galactic wind that limits the global star formation of the galaxy. We obtained high-resolution long-slit spectroscopic data with PHOENIX at Gemini South, positioning the slit on the nucleus infrared core (IRC), close to the nuclear disk major axis. The spatial resolution was 0.″35 (∼6 pc) and the slit length was 14″ (∼240 pc). The spectral resolution was ∼74,000, unprecedentedly high for galactic nuclei observations at ∼2.1 μm. The line profiles appear highly complex, with blue asymmetry up to 3.″5 away of the IRC, and red asymmetries further away to northeast. Several Gaussian components are necessary to fit the profile, nevertheless a narrow and a wide one predominate. The IRC presents kinematic widths above 700 km s-1 (FWZI), and broad component FWHM ∼ 400 km s-1, the highest detected in a nearby galaxy. At the IRC, the blueshifted broad component displays a 90 km s-1 bump in radial velocity distribution, a feature we previously detected in molecular gas kinematics. The narrow component velocity dispersion (∼32 km s-1) is within the expected for normal galaxies and luminous infrared galaxies (LIRGs). Intermediate components (FWHM ∼ 150 km s-1, redshifted to the northeast, blueshifted to the southwest) appear at some positions, as well as weaker blue (-215 km s-1) and red line wings (+300 km s-1). The IRC depicts a large broad-versus-narrow line flux ratio (F(B)/F(N) ∼ 1.35), and the broad component seems only comparable with those observed at very high star-forming rate galaxies. The results indicate that the IRC would be the main source of the galactic winds originated in the central region of NGC 253.Fil: Gunthardt, Guillermo Ivan. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; ArgentinaFil: Díaz, R. J.. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentina. Gemini Observatory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Agüero, Maria Paz. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Gimeno, G.. Gemini Observatory; Estados UnidosFil: Dottori, H.. Universidade Federal do Rio Grande do Sul; BrasilFil: Camperi, Javier Antonio. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentin

Circumnuclear Rings and Lindblad Resonances in Spiral Galaxies

In order to study the location of circumnuclear rings (CNR) and their possible relation with the inner Lindblad res- onances (ILR), we investigate a sample of spiral galaxies. For this purpose, we have obtained and analyzed medium resolution spectra of 5 spiral galaxies in the range 6200 Å to 6900 Å. Through the Hα emission line, we constructed the radial velocity curves, and then the rotation curves. By fitting them, considering two or three components of an axisy- metric Miyamoto−Nagai gravitational potential, we constructed the angular velocity and Lindblad curves. In addition, we determined the CNR radius by using the 2D spectra and generating the Hα spatial emission radial profiles.We determined the position of the resonances and we calculated the angular velocity pattern, which are in the range of 26 − 47 km s−1 kpc−1 for the galaxies of the sample. According to our results, the CNRs are located between the inner ILR (iILR) and the outer ILR (oILR), or between the center of the galaxy and the ILR, when the object has only one of such resonance; in agreement with previous results. In addition, we calculated the dimensionless parameter defined as R = RCR / Rbar, being in the range 1.1 − 1.6, in agreement with previous results found in the literature.Fil: Schmidt, Eduardo Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Mast, Damian. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Diaz, Ruben Joaquin. Gemini Observatory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Agüero, Maria Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Gunthardt, Guillermo Ivan. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Gimeno, G.. Gemini Observatory; Estados UnidosFil: Oio, Gabriel Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Gaspar, Gaia. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Milky Way Demographics with the VVV Survey II. Color Transformations and Near-Infrared Photometry for 136 Million Stars in the Southern Galactic Disk

The new multi-epoch near-infrared VVV survey (VISTA Variables in the Via Lactea) is sampling 562 sq. deg of the Galactic bulge and adjacent regions of the disk. Accurate astrometry established for the region surveyed allows the VVV data to be merged with overlapping surveys (e.g., GLIMPSE, WISE, 2MASS, etc.), thereby enabling the construction of longer baseline spectral energy distributions for astronomical targets. However, in order to maximize use of the VVV data, a set of transformation equations are required to place the VVV JHKs photometry onto the 2MASS system. The impetus for this work is to develop those transformations via a comparison of 2MASS targets in 152 VVV fields sampling the Galactic disk. The transformation coefficients derived exhibit a reliance on variables such as extinction. The transformed data were subsequently employed to establish a mean reddening law of E_{J-H}/E_{H-Ks}=2.13 +/- 0.04, which is the most precise determination to date and merely emphasizes the pertinence of the VVV data for determining such important parameters.Comment: 24 pages, 12 figures, published in A&

Milky Way demographics with the VVV survey II. Color transformations and near-infrared photometry for 136 million stars in the southern Galactic disk

Publisher's version/PDFThe new multi-epoch near-infrared VISTA Variables in the Vía Láctea (VVV) survey is sampling 562 deg[superscript 2] of the Galactic bulge and adjacent regions of the disk. Accurate astrometry established for the region surveyed allows the VVV data to be merged with overlapping surveys (e.g., GLIMPSE, WISE, 2MASS, etc.), thereby enabling the construction of longer baseline spectral energy distributions for astronomical targets. However, in order to maximize use of the VVV data, a set of transformation equations are required to place the VVV JHK[subscript s] photometry onto the 2MASS system. The impetus for this work is to develop those transformations via a comparison of 2MASS targets in 152 VVV fields sampling the Galactic disk. The transformation coefficients derived exhibit a reliance on variables such as extinction. The transformed data were subsequently employed to establish a mean reddening law of E[subscript J−H]/E[subscript H−K[subscript s]] = 2.13 [plus or minus] 0.04, which is the most precise determination to date and merely emphasizes the pertinence of the VVV data for determining such important parameters

VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way

We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010–2014), covering ∼109 point sources across an area of 520 deg2, including 33 known globular clusters and ∼350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9–2.5 μm) and a catalogue of more than 106 variable point sources. Unlike single-epoch surveys that, in most cases, only produce 2-D maps, the VVV variable star survey will enable the construction of a 3-D map of the surveyed region using well-understood distance indicators such as RR Lyrae stars, and Cepheids. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, Spitzer, HST, Chandra, INTEGRAL, WISE, Fermi LAT, XMM-Newton, GAIA and ALMA for a complete understanding of the variable sources in the inner Milky Way. This public survey will provide data available to the whole community and therefore will enable further studies of the history of the Milky Way, its globular cluster evolution, and the population census of the Galactic Bulge and center, as well as the investigations of the star forming regions in the disk. The combined variable star catalogues will have important implications for theoretical investigations of pulsation properties of stars.Facultad de Ciencias Astronómicas y Geofísica

Analysis of possible anomalies in the QSO distribution of the Flesch & Hardcastle catalogue

Aims.A recent catalogue by Flesch & Hardcastle presents two major anomalies in the spatial distribution of QSO candidates: $i)$ an apparent excess of such objects near bright galaxies, and $ii)$ an excess of very bright QSO candidates compared to random background expectations in several regions of the sky. Because anyone of these anomalies would be relevant in a cosmological context, we carried out an extensive analysis of the probabilities quoted in that catalogue. Methods.We determine the nature and redshift of a subsample of 30 sources in that catalogue by analysing their optical spectra (another 11 candidates were identified from existing public databases). These have allowed us to statistically check the reliability of the probabilities QSO status quoted by Flesch & Hardcastle for their candidates. Results.Only 12 of the 41 candidates turned out QSOs (7 of which have been identified here for the first time). Conclusions.The probabilities of the QSOs' being the candidates given by Flesch & Hardcastle are overestimated for mB ≤ 17 and for objects projected near (≤1 arcmin) bright galaxies. This is the cause of the anomalies mentioned above