arXiv subjects

J. Zamorano

Publications and source records attributed to J. Zamorano.

41 records · Page 3Linked to original sources

arXiv1999

Optical photometry of the UCM Lists I and II

We present Johnson B CCD photometry for the whole sample of galaxies of the Universidad Complutense de Madrid (UCM) Survey Lists I and II. They constitute a well-defined and complete sample of galaxies in the Local Universe with active star formation. The data refer to 191 S0 to Irr galaxies at an averaged redshift of 0.027, and complement the already published Gunn r, J and K photometries. In this paper the observational and reduction features are discussed in detail, and the new colour information is combined to search for clues on the properties of the galaxies, mainly by comparing our sample with other surveys.

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arXiv1999

Global velocity field and bubbles in the BCD Mrk86

We have studied the velocity field of the Blue Compact Dwarf galaxy Mrk86 (NGC2537) using data provided by 14 long-slit optical spectra. This kinematical information is complemented with narrow-band ([OIII]5007A and Halpha) and broad-band (B, V, Gunn-r and K) imaging. The analysis of the galaxy global velocity field suggests that the ionized gas could be distributed in a rotating inclined disk, with projected central angular velocity of Omega=34 km/s/kpc. The comparison between the stellar, HI and modeled dark matter density profile, indicates that the total mass within its optical radius is dominated by the stellar component. Peculiarities observed in its velocity field can be explained by irregularities in the ionized gas distribution or local motions induced by star formation. Kinematical evidences for two expanding bubbles, Mrk86-B and Mrk86-C, are given. They show expanding velocities of 34 km/s and 17 km/s, Halpha luminosities of 3x10^38 erg/s and 1.7x10^39 erg/s, and physical radii of 374 and 120 pc, respectively. The change in the [SII]/Halpha, [NII]/Halpha, [OII]/[OIII] and [OIII]/Hbeta line ratios with the distance to the bubble precursor suggests a diminution in the ionization parameter and, in the case of Mrk86-B, an enhancement of the shock-excited gas emission. The optical-near-infrared colours of the bubble precursors are characteristic of low metallicity star forming regions (0.2 Zsun) with burst strengths of about 1 per cent in mass.

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arXiv1999

Survey for Emission-Line Galaxies: Universidad Complutense de Madrid List 3

A new low-dispersion objective-prism search for low-redshift (z<0.045) emission-line galaxies (ELG) has been carried out by the Universidad Complutense de Madrid with the Schmidt Telescope at the Calar-Alto Observatory. This is a continuation of the UCM Survey, which was performed by visual selection of candidates in photographic plates via the presence of the Halpha+[NII]6584 blend in emission. In this new list we have applied an automatic procedure, fully developed by us, for selecting and analyzing the ELG candidates on the digitized images obtained with the MAMA machine. The analyzed region of the sky covers 189 square degrees in nine fields near R.A.=14h & 17h, Dec=25 deg. The final sample contains 113 candidates. Special effort has been made to obtain a large amount of information directly from our uncalibrated plates by using several external calibrations. The parameters obtained for the ELG candidates allow for the study of the statistical properties for the sample.

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arXiv1996

Spectroscopic properties, spatial and luminosity distributions of the UCm survey galaxies

A spectroscopic analysis of the whole sample of H$α$ Emission-Line Galaxies (ELGs) contained in the lists 1 & 2 of the Universidad Complutense de Madrid (UCM) objective-prism survey is presented. A significant fraction (59\%) of star-forming galaxies with low ionization or high extinction properties has been found. This kind of ELG is only incompletely detected in the blue or in other ELG surveys. We have found evidence for evolution among some of the different ELG classes. A comparison between the populations detected by Case, Kiso, UM and UCM surveys is presented. We conclude that a deep H$α$ survey is better able to sample all the ages, evolutionary stages and luminosities of current star-forming galaxies than other surveys using blue-emission lines or colors. Finally, the luminosity and spatial distributions of the UCM galaxies are determined. The contribution of the newly found current star-forming ELGs adds new clues to galaxy evolution and has to be taken into account when trying to consider the density of ELGs and total Star Formation Rate in the Universe.

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arXiv1995

The Current Star Formation Rate of the Local Universe

The Universidad Complutense de Madrid (UCM) Survey is a long-term project aiming at finding and analysing star-forming galaxies detected by their H$α$ emission in Schmidt objective-prism plates. The instrumental set-up limits the volume of the Universe surveyed to a redshift $z\lesssim0.045$. So far we have discovered several hundred emission-line galaxies (ELGs) undergoing star formation at a wide range of levels. Analyzing a complete sample of ELGs from the UCM survey we have computed the H$α$ luminosity function for the star-forming galaxies in the surveyed volume of the Universe. A Schechter function provides a good fit to the H$α$ luminosity function with the following parameters: $α= -1.3\pm0.2$; $L^*({\rm H}α) = 10^{42.15\pm0.08} $erg$ $s$^{-1}$ and $ϕ^*=10^{-3.2\pm0.2} $Mpc$^{-3}$ for $H_0 = 50 $km$ $s$^{-1} $Mpc$^{-1}$. Integrating over the full range of luminosities, we obtain an H$α$ luminosity density of $10^{39.1\pm0.2} $erg$ $s$^{-1} $Mpc$^{-3}$. Using the H$α$ emission as a star formation rate (SFR) estimator, this translates into a SFR density for the Local Universe of $0.013^{+0.007}_{-0.005} M_{\odot} $yr$^{-1} $Mpc$^{-3}$ in star-forming galaxies with $EW($H$α+$[NII]$)>10$Åand $z\lesssim0.045$, for a Scalo Initial Mass Function. This is the first observational determination of this quantity, which will provide a direct test of current galaxy formation and evolution models.

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