arXiv subjects

A. M. Pérez García

Publications and source records attributed to A. M. Pérez García.

22 records · Page 2Linked to original sources

arXiv2009

On the Anticorrelation Between Galaxy Light Concentration and X-ray-to-Optical Flux Ratio

Active Galactic Nuclei (AGN) play an important role in many aspects of the modern cosmology, and of particular interest is the issue of the interplay between AGN and their host galaxy. Using X-ray and optical data sets, we have explored the properties of a large sample of AGNs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and studied their evolution in relation with the evolution of their host galaxy. We present here an anticorrelation between X-ray-to-optical flux ratio (X/O) and galaxy light concentration (C), which has been found for the first time and might suggest that early type galaxies, having poor matter supply to feed the AGN activity, have lower Eddington rates than those of late type galaxies.

astro-ph.CO↗

arXiv2009

OTELO Survey: Deep BVRI broadband photometry of the Groth strip. II Properties of X-ray Emitters

The Groth field is one of the sky regions that will be targeted by the OTELO (OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and 920 nm atmospheric windows. This field has been observed by AEGIS (All-wavelength Extended Groth strip International Survey) covering the full spectral range, from X-rays to radio waves. Chandra X-ray data with total exposure time of 200ksec are analyzed and combined with optical broadband data of the Groth field in order to study a set of structural parameters of the X-ray emitters and its relation with X-ray properties. We processed the raw, public X-ray data using the Chandra Interactive Analysis of Observations and determined and analyzed different structural parameters in order to produce a morphological classification of X-ray sources. Finally, we analyzed the angular clustering of these sources using 2-point correlation functions. We present a catalog of 340 X-ray emitters with optical counterpart. We obtained the number counts and compared them with AEGIS data. Objects have been classified by nuclear type using a diagnostic diagram relating X-ray-to-optical ratio (X/O) to hardness ratio (HR). Also, we combined structural parameters with other X-ray and optical properties, and found for the first time an anticorrelation between the X/O ratio and the Abraham concentration index which might suggest that early type galaxies have lower Eddington rates than those of late type galaxies. A significant positive angular clustering was obtained from a preliminary analysis of 4 subsamples of the X-ray sources catalog. The clustering signal of the opticaly extended counterparts is similar to that of strongly clustered populations like red and very red galaxies, suggesting that the environment plays an important role in AGN phenomena.

astro-ph.CO↗

arXiv2009

Evolution of the optical Tully-Fisher relation up to z=1.3

The study of the evolution of the Tully-Fisher relation has been controversial in the past years. The main difficulty is in determining the required parameters for intermediate and high redshift galaxies. This work aims to identify the main problems of the study of the Tully-Fisher relation at high redshift using optical emission lines, in order to draw conclusions about the possible evolution of this relation in the B, R, and I-bands. With this aim, the rotational velocities obtained from the widths of different optical lines using DEEP2 spectra are compared. Morphology has been determined via HST images, using and comparing different methodologies. Instrumental magnitudes are then corrected for K and extinction and the absolute magnitudes derived for the concordance cosmological model. Finally, the optical Tully-Fisher relations in B, R, and I-bands at different redshifts up to z = 1.3 are derived. Although most studies (this one included) find evidence of evolution, the results are not conclusive enough, since the possible luminosity evolution is within the scattering of the relation, and the evolution in slope is difficult to determine because at high redshift only the brightest galaxies can be measured. Nevertheless, our study shows a clear tendency, which is the same for all bands studied, that favours a luminosity evolution where galaxies were brighter in the past for the same rotation velocity. This result also implies that the colour of the Tully-Fisher relation does not change with redshift, supporting the collapse model versus the accretion model of disc galaxy formation.

astro-ph.CO↗

arXiv2006

The Narrow Line Region of the Seyfert 2 galaxy Mrk 78. An infrared view

We report near-infrared spectroscopic data for the Seyfert 2 galaxy Mrk 78, taken with the LIRIS near-infrared camera/spectrometer at the William Herschel Telescope (WHT). The long-slit spectra clearly show extended emission. The resolution and depth of the near-infrared spectra allows the examination of its morphology and ionization regions, and a direct comparison with similarly deep visible spectra. The emission-line ratios obtained are used to derive the extinction towards the nucleus. The detection of strong features such as [Fe II], H$_{2}$, hydrogen recombination lines and the coronal [Si VI]$λ$1.962 line is used to study the kinematics and excitation mechanisms occurring in Mrk 78, revealing that despite of the strong radio-jet interaction present in this object, photoionization from the active nucleus dominates the narrow line region emission, while UV fluorescence is the source of the H$_{2}$ emission. Lines with extended emission yield velocity distributions with an amplitude of about 600 km/s, the consequence of an eastern lobe moving away from us plus a western lobe with the opposite contribution. We used the photoionization code CLOUDY to recreate a typical narrow line region region, to derive the ionization parameter, and to compare our spectral data with diagnostic diagrams.

astro-ph↗