arXiv subjects

Jaime Zamorano

Publications and source records attributed to Jaime Zamorano.

35 records · Page 2Linked to original sources

arXiv2013

Evolution of the energy consumed by street lighting in Spain estimated with DMSP-OLS data

We present the results of the analysis of satellite imagery to study light pollution in Spain. Both calibrated and non-calibrated DMSP-OLS images were used. We describe the method to scale the non-calibrated DMSP-OLS images which allows us to use differential photometry techniques in order to study the evolution of the light pollution. Population data and DMSP-OLS satellite calibrated images for the year 2006 were compared to test the reliability of official statistics in public lighting consumption. We found a relationship between the population and the energy consumption which is valid for several regions. Finally the true evolution of the electricity consumption for street lighting in Spain from 1992 to 2010 was derived, it have been doubled in the last 18 years in most of the provinces.

astro-ph.IM↗

arXiv2013

Analysis of a superbolide from a Damocloid observed over Spain on July 13, 2012

A superbolide with an estimated absolute magnitude of -20+-1 was seen on July 13, 2012 over the center and south of Spain. This extraordinary event, which was witnessed by numerous casual observers, was recorded in the framework of the continuous fireball monitoring and meteor spectroscopy campaign performed by the SPanish Meteor Network (SPMN). Thus, because of optimal weather conditions, the bolide was imaged from ten meteor observing stations. Here we present the analysis of this magnificent event, which is the brightest fireball ever recorded by our team. The atmospheric trajectory of the bolide and the orbit in the Solar System of the parent meteoroid were obtained. The emission spectrum produced during the ablation of this particle is also discussed. We found that the meteoroid, which was following a Halley Type Comet orbit, was depleted in Na and had a tensile strength one order of magnitude higher than that corresponding to typical cometary materials. By means of orbital analysis tools we have investigated the likely parent body of this particle and the results suggest that the progenitor is a damocloid. The impact area of the hypothetical remnants of the meteoroid is also given and a search for meteorites was performed, but none were found.

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arXiv2013

Characterization of the candidate site for the Cherenkov Telescope Array at the Observatorio del Teide

The Spanish partners of the future Cherenkov Telescope Array (CTA) have selected a candidate site for the Northern installation of CTA, at 3 km from the Observatorio del Teide (OT), in the Canary Island of Tenerife. As the OT is a very well-characterized astronomical site. We focus here on differences between the publicly accessible measurements from the OT observatory and those obtained with instruments deployed at the candidate site. We find that the winds are generally softer at the candidate site, and the level of background light comparable to the Observatorio del Roque de los Muchachos (ORM) at La Palma in the B-band, while it is only slightly higher in the V-band.

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arXiv2013

The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth

On October 8th, 2011 the Earth crossed the dust trails left by comet 21P/Giacobini-Zinner during its XIX and XX century perihelion approaches with the comet being close to perihelion. The geometric circumstances of that encounter were thus favorable to produce a meteor storm, but the trails were much older than in the 1933 and 1946 historical encounters. As a consequence the 2011 October Draconid display exhibited several activity peaks with Zenithal Hourly Rates of about 400 meteors per hour. In fact, if the display had been not forecasted, it could have passed almost unnoticed as was strongly attenuated for visual observers due to the Moon. This suggests that most meteor storms of a similar nature could have passed historically unnoticed under unfavorable weather and Moon observing conditions. The possibility of obtaining information on the physical properties of cometary meteoroids penetrating the atmosphere under low-geocentric velocity encounter circumstances motivated us to set up a special observing campaign. Added to the Spanish Fireball Network wide-field all-sky and CCD video monitoring, other high-sensitivity 1/2" black and white CCD video cameras were attached to modified medium-field lenses for obtaining high resolution orbital information. The trajectory, radiant, and orbital data of 16 October Draconid meteors observed at multiple stations are presented. The results show that the meteors appeared from a geocentric radiant located at R.A.=263.0+-0.4 deg. and Dec.=+55.3+-0.3 deg. that is in close agreement with the radiant predicted for the 1873-1894 and the 1900 dust trails. The estimated mass of material from 21P/Giacobini-Zinner delivered to Earth during the six-hours outburst was around 950+-150 kg.

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arXiv2013

Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution

Galaxy mergers are considered as questionable mechanisms for the evolution of lenticular galaxies (S0's), on the basis that even minor ones induce structural changes that are difficult to reconcile with the strong bulge-disk coupling observed in the photometric scaling relations of S0's. We check if the evolution induced onto S0's by dry intermediate and minor mergers can reproduce their photometric scaling relations, analysing the bulge-disk decompositions of the merger simulations presented in Eliche-Moral et al. (2012). The mergers induce an evolution in the photometric planes compatible with the data of S0's, even in those ones indicating a strong bulge-disk coupling. The mergers drive the formation of the observed photometric relation in some cases, whereas they induce a slight dispersion compatible with data in others. Therefore, this evolutionary mechanism tends to preserve these scaling relations. In those photometric planes where the morphological types segregate, the mergers always induce evolution towards the region populated by S0's. The structural coupling of the bulge and the disk is preserved or reinforced because the mergers trigger internal secular processes in the primary disk that induce significant bulge growth, even although these models do not induce bars. Intermediate and minor mergers can thus be considered as plausible mechanisms for the evolution of S0's attending to their photometric scaling relations, as they can preserve and even strengthen any pre-existing structural bulge-disk coupling, triggering significant internal secular evolution (even in the absence of bars or dissipational effects). This means that it may be difficult to isolate the effects of pure internal secular evolution from those of the merger-driven one in present-day early-type disks (abridged).

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arXiv2012

SHARDS: an optical spectro-photometric survey of distant galaxies

(Abridged) We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out with GTC/OSIRIS. SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field (130 arcmin^2) at wavelengths 500 to 950 nm and using 24 contiguous medium-band filters (spectral resolution R 50). The data reach 26.5 mag (>3-sigma level) with sub-arcsec seeing in all bands. SHARDS main goal is obtaining accurate physical properties of interm- and high-z galaxies using well-sampled optical SEDs with sufficient spectral resolution to measure absorption and emission features. Among the different populations of high-z galaxies, SHARDS principal targets are massive quiescent galaxies at z>1. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures applied to the GTC/OSIRIS data. We present science demonstration results about the detection and study of emission-line galaxies (star-forming and AGN) at z=0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies at 1.0<z<1.4. We discuss on the improvements introduced by the SHARDS dataset in the analysis of their SFH and stellar properties. We discuss the systematics arising from the use of different stellar population libraries. We find that the UV-to-MIR SEDs of the massive quiescent galaxies at z=1.0-1.5 are well described by an exponential decaying SFH with scale tau=100-200 Myr, age 1.5-2.0 Gyr, solar or slightly sub-solar metallicity, and moderate extinction, A(V)~0.5 mag. We also find that galaxies with masses above M* are typically older than lighter galaxies, as expected in a downsizing scenario of galaxy formation. This trend is, however, model dependent, i.e., it is significantly more evident in the results obtained with some stellar population synthesis libraries and almost absent in others.

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arXiv2012

Evolution along the sequence of S0 Hubble types induced by dry minor mergers. I - Global bulge-to-disk structural relations

Recent studies have argued that galaxy mergers are not important drivers for the evolution of S0's, on the basis that mergers cannot preserve the coupling between the bulge and disk scale-lengths observed in these galaxies and the lack of correlation of their ratio with the S0 Hubble type. We investigate whether the remnants resulting from collision-less N-body simulations of intermediate and minor mergers onto S0 galaxies evolve fulfilling global structural relations observed between the bulges and disks of these galaxies. Different initial bulge-to-disk ratios of the primary S0 have been considered, as well as different satellite densities, mass ratios, and orbits of the encounter. We have analysed the final morphology of the remnants in images simulating the typical observing conditions of S0 surveys. We derive bulge+disk decompositions of the final remnants to compare their global bulge-to-disk structure with observations. We show that all remnants present undisturbed S0 morphologies according to the prescriptions of specialized surveys. The dry intermediate and minor mergers induce noticeable bulge growth (S0c --> S0b and S0b --> S0a), but affect negligibly to the bulge and disk scale-lengths. Therefore, if a coupling between these two components exists prior to the merger, the encounter does not break this coupling. This fact provides a simple explanation for the lack of correlation between the ratio of bulge and disk scale-lengths and the S0 Hubble type reported by observations. These models prove that dry intermediate and minor mergers can induce global structural evolution within the sequence of S0 Hubble types compatible with observations, meaning that these processes should not be discarded from the evolutionary scenarios of S0's just on the basis of the strong coupling observed between the bulge and disk scale-lengths in these galaxies (abridged).

astro-ph.CO↗

arXiv2012

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0's through major mergers

Some recent observations seem to disagree with hierarchical theories of galaxy formation about the role played by major mergers in the late buildup of massive E-S0's. We re-address this question by analysing the morphology, structural distortion level, and star formation enhancement of a sample of massive galaxies (M_* > 5 * 10^10 Msun) lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an initial sample of ~1800 sources with K_s < 20.5 mag over an area ~155 arcmin^2 on the Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA Survey. Red galaxy classes that can be directly associated to intermediate stages of major mergers and to their final products have been defined. We report observational evidence of the existence of a dominant evolutionary path among massive red galaxies at 0.6 10^11 Msun at z=0 through gas-rich major mergers has frozen since z~0.6. All these facts support that major mergers have played the dominant role in the definitive buildup of present-day E-S0's with M_*> 10^11 Msun at 0.6<z<1.2, in good agreement with hierarchical scenarios of galaxy formation.

astro-ph.CO↗

arXiv2012

Integral Field Spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC5668: an unusual flattening in metallicity gradient

We present the analysis of the full bi-dimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the PPAK IFU at the Calar Alto observatory 3.5m telescope. We make use of broad-band imaging to provide further constraints on the evolutionary history of the galaxy. This dataset will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that, while inwards of r\,$\sim\,36",\sim$\,4.4kpc\,$\sim$\,0.36\,$(\frac {D_{25}}{2})$ the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r$\sim36"$ flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of $λ$=0.053 and v$_{c}$=167\,km\,s$^{-1}$, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r\,$\sim36\arcsec$. The same is true for the colors despite of some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

astro-ph.GA↗

arXiv2011

UV-to-FIR analysis of Spitzer/IRAC sources in the Extended Groth Strip II: Photometric redshifts, Stellar masses and Star formation rates

Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Barro et al. 2011a, Paper I), we present a detailed SED analysis of nearly 80,000 IRAC 3.6+4.5 micron selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] < 23.75 (85% completeness level of the IRAC survey) over 0.48 square degrees. The typical photometric redshift accuracy is Delta z/(1+z)=0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and IMFs in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 micron data available in the EGS. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z$\gtrsim$1.5 observed when only MIPS 24 micron data is available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the web-interface utility Rainbow-navigator

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arXiv2010

The coordinated key role of wet, mixed, and dry major mergers in the buildup of massive early-type galaxies at z<~1

Hierarchical models predict that massive early-type galaxies (mETGs) derive from the most massive and violent merging sequences occurred in the Universe. However, the role of wet, mixed, and dry major mergers in the assembly of mETGs is questioned by some recent observations. We have developed a semi-analytical model to test the feasibility of the major-merger origin hypothesis for mETGs, just accounting for the effects on galaxy evolution of the major mergers strictly reported by observations. The model proves that it is feasible to reproduce the observed number density evolution of mETGs since z~1, just accounting for the coordinated effects of wet/mixed/dry major mergers. It can also reconcile the different assembly redshifts derived by hierarchical models and by mass downsizing data for mETGs, just considering that a mETG observed at a certain redshift is not necessarily in place since then. The model predicts that wet major mergers have controlled the mETGs buildup since z~1, although dry and mixed mergers have also played an essential role in it. The bulk of this assembly took place at 0.7<z<1, being nearly frozen at z<~0.7 due to the negligible number of major mergers occurred per existing mETG since then. The model suggests that major mergers have been the main driver for the observational migration of mass from the massive end of the blue galaxy cloud to that of the red sequence in the last ~8 Gyr.

astro-ph.CO↗

arXiv2010

Reconciling a significant hierarchical assembly of massive early-type galaxies at z<~1 with mass downsizing

Hierarchical models predict that massive early-type galaxies (mETGs) are the latest systems to be in place into the cosmic scenario (at z<~0.5), conflicting with the observational phenomenon of galaxy mass downsizing, which poses that the most massive galaxies have been in place earlier that their lower-mass counterparts (since z~0.7). We have developed a semi-analytical model to test the feasibility of the major-merger origin hypothesis for mETGs, just accounting for the effects on galaxy evolution of the major mergers strictly reported by observations. The most striking model prediction is that very few present-day mETGs have been really in place since z~1, because ~90% of the mETGs existing at z~1 are going to be involved in a major merger between z~1 and the present. Accounting for this, the model derives an assembly redshift for mETGs in good agreement with hierarchical expectations, reproducing observational mass downsizing trends at the same time.

astro-ph.CO↗

arXiv2008

Light pollution in Spain. An european perspective

Spain appears in light pollution maps as a country less polluted than their neighbours in the European Union. This seems to be an illusion due to its low population density. The data indicate that Spain is one of the most contaminated countries. To reach these conclusions we compare the Spanish case to those of other European countries.

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arXiv2008

Exploring the evolutionary paths of the most massive galaxies since z~2

We use Spitzer MIPS data from the FIDEL Legacy Project in the Extended Groth Strip to analyze the stellar mass assembly of massive (M>10^11 M_sun) galaxies at z<2 as a function of structural parameters. We find 24 micron emission for more than 85% of the massive galaxies morphologically classified as disks, and for more than 57% of the massive systems morphologically classified as spheroids at any redshift, with about 8% of sources harboring a bright X-ray and/or infrared emitting AGN. More noticeably, 60% of all compact massive galaxies at z=1-2 are detected at 24 micron, even when rest-frame optical colors reveal that they are dead and evolving passively. For spheroid-like galaxies at a given stellar mass, the sizes of MIPS non-detections are smaller by a factor of 1.2 in comparison with IR-bright sources. We find that disk-like massive galaxies present specific SFRs ranging from 0.04 to 0.2 Gyr^-1 at z<1 (SFRs ranging from 1 to 10 M_sun/yr), typically a factor of 3-6 higher than massive spheroid-like objects in the same redshift range. At z>1, and more pronouncedly at z>1.3, the median specific SFRs of the disks and spheroids detected by MIPS are very similar, ranging from 0.1 to 1 Gyr^-1 (SFR=10-200 M_sun/yr). We estimate that massive spheroid-like galaxies may have doubled (at the most) their stellar mass from star-forming events at z<2: less than 20% mass increase at 1.7<z<2.0, up to 40% more at 1.1<z<1.7, and less than 20% additional increase at z<1. Disk-like galaxies may have tripled (at the most) their stellar mass at z<2 from star formation alone: up to 40% mass increase at 1.7<z<2.0, and less than 180% additional increase below z=1.7 occurred at a steady rate.

astro-ph↗

arXiv2008

The stellar mass assembly of galaxies from z=0 to z=4. Analysis of a sample selected in the rest-frame near-infrared with Spitzer

Using a sample of ~28,000 sources selected at 3.6-4.5 microns with Spitzer observations of the HDF-N, the CDF-S, and the Lockman Hole (surveyed area: ~664 arcmin^2), we study the evolution of the stellar mass content of the Universe at 0 10^12.0 M_sun) assembled the bulk of their stellar content rapidly (in 1-2 Gyr) beyond z~3 in very intense star formation events (producing high specific SFRs). Galaxies with 10^11.5 2.5 is dominated by optically faint (R>25) red galaxies (Distant Red Galaxies or BzK sources) which account for ~30% of the global population of galaxies, but contribute at least 60% to the cosmic stellar mass density. Bluer galaxies (e.g., Lyman Break Galaxies) are more numerous but less massive, contributing less than 50% to the global stellar mass density at high redshift.

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arXiv2007

The Halpha-based Star Formation Rate Density of the Universe at z=0.84

We present the results of an Halpha near-infrared narrow-band survey searching for star-forming galaxies at redshift z=0.84. This work is an extension of our previous narrow-band studies in the optical at lower redshifts. After removal of stars and redshift interlopers (using spectroscopic and photometric redshifts), we build a complete sample of 165 Halpha emitters in the Extended Groth strip and GOODS-N fields with L(Halpha)>10^41 erg/s. We compute the Halpha luminosity function at z=0.84 after corrections for [NII] flux contamination, extinction, systematic errors, and incompleteness. Our sources present an average dust extinction of A(Halpha)=1.5 mag. Adopting Halpha as a surrogate for the instantaneous star formation rate (SFR), we measure a extinction-corrected SFR density of 0.17+-0.03 M_sun/yr/Mpc3. Combining this result to our prior measurements at z=0.02, 0.24, and 0.40, we derive an Halpha-based evolution of the SFR density proportional to (1+z)^beta with beta=3.8+-0.5. This evolution is consistent with that derived by other authors using different SFR tracers.

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arXiv2007

A contribution to the selection of emission-line galaxies using narrow-band filters in the optical airglow windows

Emission line galaxies are an invaluable tool for our understanding of the evolution of galaxies in the Universe. Imaging of deep fields with narrow-band filters allows not only the selection of these objects, but also to infer the line flux and the equivalent width of the emission line with some assumptions. The narrow-band filter technique provides homogeneous samples of galaxies in small comoving volumes in the sky. We present an analysis of the selection of emission-line galaxies using narrow-band filters. Different methods of observation are considered: broad-band -- narrow-band filters and two broad-band and one narrow-band filters. We study also the effect of several lines entering simultaneously inside the filters (this is the case of Halpha). In each case the equations to obtain the equivalent width and line flux from the photometry are obtained. Candidates to emission-line objects are selected by their color excess in a magnitude-color diagram. For different narrow-band filters, we compute the mean colors of stars and galaxies, showing that, apart from galaxies, some types of stars could be selected with certain filter sets. We show how to compute the standard deviation of the colors of the objects even in the usual case when there are not enough objects to determine the standard deviation from the data. We present also helpful equations to compute the narrow-band and the broad-band exposure times in order to obtain minimum dispersion in the ratio of fluxes of both bands with minimum total exposure time.

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