arXiv subjects

I. Márquez

Publications and source records attributed to I. Márquez.

77 records · Page 5Linked to original sources

arXiv2008

The ALHAMBRA Project: A large area multi medium-band optical and NIR photometric survey

(ABRIDGED) We describe the first results of the ALHAMBRA survey which provides cosmic tomography of the evolution of the contents of the Universe over most of Cosmic history. Our approach employs 20 contiguous, equal-width, medium-band filters covering from 3500 to 9700 A, plus the JHKs bands, to observe an area of 4 sqdeg on the sky. The optical photometric system has been designed to maximize the number of objects with accurate classification by SED and redshift, and to be sensitive to relatively faint emission lines. The observations are being carried out with the Calar Alto 3.5m telescope using the cameras LAICA and O-2000. The first data confirm that we are reaching the expected magnitude limits of AB<~25 mag in the optical filters from the blue to 8300 A, and from AB=24.7 to 23.4 for the redder ones. The limit in the NIR is (Vega) K_s~20, H~21, J~22. We expect to obtain accurate redshift values, Delta z/(1+z) <~ 0.03 for about 5x10^5 galaxies with I<~25 (60% complete), and z_med=0.74. This accuracy, together with the homogeneity of the selection function, will allow for the study of the redshift evolution of the large scale structure, the galaxy population and its evolution with redshift, the identification of clusters of galaxies, and many other studies, without the need for any further follow-up. It will also provide targets for detailed studies with 10m-class telescopes. Given its area, spectral coverage and its depth, apart from those main goals, the ALHAMBRA-Survey will also produce valuable data for galactic studies.

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arXiv2005

GRB 050509b: the elusive optical/nIR/mm afterglow of a short-duration GRB

We present multiwavelength (optical/near infrared/millimetre) observations of a short duration gamma-ray burst detected by Swift (GRB 050509b) collected between 0 seconds and ~18.8 days after the event. No optical, near infrared or millimetre emission has been detected in spite of the well localised X-ray afterglow, confirming the elusiveness of the short duration events. We also discuss the possibility of the burst being located in a cluster of galaxies at z= 0.225 or beyond. In the former case, the spectral energy distribution of the neighbouring, potential host galaxy, favours a system harbouring an evolved dominant stellar population (age ~360 Myr), unlike most long duration GRB host galaxies observed so far, i.e. thus giving support to a compact binary merger origin. Any underlying supernova that could be associated with this particular event should have been at least 3 magnitudes fainter than the type Ib/c SN 1998bw and 2.3 magnitudes fainter than a typical type Ia SN.

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arXiv2004

Properties of Isolated Disk Galaxies

A sample of isolated galaxies (IsG), selected by the ratio, $f$, between inner and tidal forces acting upon a galaxy, is presented. The analysis of the Coma cluster lead us to adopt the criterion $f\leq -4.5$ for IsG. The candidates are from the CfA catalog with cz $\leq$5000 km/s, |b|> 40°, DEC $\ge -$2.5°. The sample contains 203 objects from the initial 1706. We also selected a sample (N=130) of perturbed galaxies, i.e., with companions (with known z, $Δ(cz)\le 500$ km/s), $f\geq-$2. The comparison of both samples shows significant differences in morphology, size, mass, luminosity and colors. Sc spirals are more frequent among IsG, and S0s among perturbed galaxies. IsG appear to be smaller, less luminous and bluer than interacting objects. We also found that bars are twice as frequent among perturbed galaxies in particular for early S and S0. The perturbed galaxies have higher L$_{FIR}$/L$_B$ and M$_{mol}$/L$_B$ ratios, but the atomic gas content is similar for the two samples. The L-size and M-L relations shows similar trends, the main difference being the almost total absence of big, bright and massive galaxies among the IsG, and the almost total absence of small, faint and low mass galaxies among the perturbed systems. The evolution induced by interactions, would therefore proceed from late, small, faint and low mass S to earlier, bigger, more luminous and more massive S and S0 galaxies, producing at the same time a larger fraction of barred galaxies, but preserving the same relations between global parameters. The properties of local IsG are similar to those of high redshift galaxies, suggesting that the present day isolated galaxies could be quietly evolved, unused {\sl building blocks} surviving in low density environments.

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arXiv2001

The Hamburg/SAO Survey for Emission--Line Galaxies. V. The Fifth List of 161 Galaxies

We present the fifth list with results of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO -- Special Astrophysical Observatory, Russia). The list is a result of follow-up spectroscopy conducted with the 2.2m CAHA and 4m Kitt Peak telescopes in 1999. The data of this snap-shot spectroscopy survey confirmed 166 emission-line objects out of 209 observed candidates and allowed their quantitative spectral classification and redshift determination. We could classify 98 emission-line objects as BCG/HII galaxies or probable BCGs, 5 -- as QSOs, 3 - as Seyfert galaxies, 2 - as super-associations in subluminous spiral galaxies. 25 low-excitation objects were classified as starburst nuclei (SBN), 24 as dwarf amorphous nuclei starburst galaxies (DANS) and 3 as LINERs. Due to low signal-to-noise ratio we could not classify 6 ELGs. Furthermore, for another 4 galaxies we did not detect any significant emission lines. For 131 emission-line galaxies, the redshifts and/or line intensities are determined for the first time. For the remaining 30 previously known ELGs we give either improved data of the line intensities or some independent measurements.

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arXiv1997

The dynamical status of Stephan's Quintet

Multiwavelength data for Stephan's Quintet (SQ) are consistent with the following model for this compact galaxy group. (1) Discordant redshift NGC 7320 is an unrelated foreground galaxy. (2) In the past SQ was an accordant redshift quartet involving NGC 7317, 18A, 19 and 20C. NGC 7320C collided (probably not for the first time) with the group a few times 10$^8$ years ago and stripped the interstellar matter from NGC 7319. (3) In the present SQ is again an accordant quartet involving NGC 7317, 18A,B, and 19. NGC 7318B is now entering the group at high velocity for the first time, giving rise to a shock zone. If most compact groups are like SQ, then they are frequently visited by infalling n eighbors that perturb the group and themselves. SQ represents strong evidence for secondary infall in a small group environment. Tidal stripping reduces the mass of the infalling galaxies, thereby increasing the timescale for their orbital decay. There is little evidence that these high velocity ``intruders'' are rapidly captured and/or merge with the system. Instead they are the mechanism that sustains compact groups against collapse. Efficient gas stripping may account for the low star formation rate observed in compact groups and infall of residual gas into galactic nuclei may also foster the onset of AGN activity.

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