arXiv subjects

G. F. Hagele

Publications and source records attributed to G. F. Hagele.

22 records · Page 2Linked to original sources

arXiv2010

Internal kinematic and physical properties in a BCD galaxy: Haro 15 in detail

We present a detailed study of the kinematic and physical properties of the ionized gas in multiple knots of the blue compact dwarf galaxy Haro 15. Using echelle and long slit spectroscopy data, obtained with different instruments at Las Campanas Observatory, we study the internal kinematic and physical conditions (electron density and temperature), ionic and total chemical abundances of several atoms, reddening and ionization structure. Applying direct and empirical methods for abundance determination, we perform a comparative analysis between these regions and in their different components. On the other hand, our echelle spectra show complex kinematics in several conspicuous knots within the galaxy. To perform an in-depth 2D spectroscopic study we complete this work with high spatial and spectral resolution spectroscopy using the Integral Field Unit mode on the Gemini Multi-Object Spectrograph instrument at the Gemini South telescope. With these data we are able to resolve the complex kinematical structure within star forming knots in Haro 15 galaxy.

astro-ph.CO↗

arXiv2009

Characterization of the emitting and absorbing media around the nucleus of the active galaxy UGC11763 using XMM-Newton data

Aims. The detailed analysis of all data taken by the XMM-Newton satellite of UGC11763 to characterize the different components that are emitting and absorbing radiation in the vicinity of the active nucleus. Methods. The continuum emission was studied through the EPIC spectra taking profit of the spectral range of these cameras. The high resolution RGS spectra were analyzed in order to characterize the absorbing features and the emission line features that arise in the spectra of this source. Results. A power law with a photon index Γ= 1.72^{+0.03}_{-0.01} accounts for the continuum emission of this source in the hard X-rays from 10 down to 1 keV. At lower energies, a black body model with kT= 0.100\pm 0.003 keV provides a good description of the observed soft excess. The absorption signatures in the spectra of UGC11763 are consistent with the presence of a two phase ionized material (log U=1.65^{+0.07}_{-0.08}; 2.6\pm 0.1 and log N_{H} = 21.2\pm 0.2; 21.51\pm 0.01 cm^{-2}, respectively) in the line of sight. The physical conditions found are consistent with the two phases being in pressure equilibrium. The low ionization component is more ionized than typically found for warm absorbers in other Seyfert 1 galaxies. There are also signatures of some emission lines: Ovii He$α$(r), Ovii He$α$(f), a blend of the Neix He$α$ triplet and Fexviii at λ17.5 Å.

astro-ph.GA↗

arXiv2009

Star Formation in HII Galaxies. Properties of the ionized gas

We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the XXI century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should superseed currently used ones based on very simple, and poorly tested, photo-ionization model sequences. Then, these observations are analysed applying a methodology designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen, neon, argon and iron in the ionsied gas. Four electron temperatures and one electron density are derived from the observed forbidden line ratios using the five-level atom approximation. For our best objects errors of 1% in T([OIII]), 3% in T([OII]) and 5% in T([SIII]) are achieved with a resulting accuracy between 5 and 9% in total oxygen abundances, O/H. These accuracies are expected to improve as better calibrations based on more precise measurements, both on electron temperatures and densities, are produced.

astro-ph.GA↗

arXiv2006

The metallicity of circumnuclear star forming regions

We present a spectrophotometric study of circumnuclear star forming regions (CNSFR) in the early type spiral galaxies: NGC 2903, NGC 3351 and NGC 3504, all of them of over solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is made after careful subtraction of the very prominent underlying stellar absorption. It is found that most regions show the highest abundances in HII region-like objects. The relative N/O and S/O abundances are discussed. In is also shown that CNSFR, as a class, segregate from the disk HII region family, clustering around smaller ``softness parameter" -- η' -- values, and therefore higher ionizing temperatures.

astro-ph↗