Análisis de las masas estelares de una muestra de galaxias luminosas compactas azules

Este trabajo está orientado a calcular las masas estelares de una muestra de galaxias luminosas compactas azules (LBCGs) a partir de la fotometría en filtros ópticos y del infrarrojo cercano. Se han medido también las masas estelares para muestras de galaxias espirales y elípticas a modo de comparación. Para la determinación de las masas estelares hemos desarrollado un código donde se ajusta la fotometría sintética de modelos de síntesis de poblaciones a la fotometría multibanda observada de las galaxias. Estos ajustes permiten derivar, además de la masa estelar, otras propiedades interesantes de estas galaxias: el tiempo que hace que ocurrió un evento importante de formación estelar y la fuerza del mismo, la existencia y edad de una población subyacente y su masa estelar. Mediante simulaciones, determinamos que, a pesar de que distintos valores de la metalicidad, extinción por polvo y función inicial de masas dan lugar a soluciones degeneradas, la masa estelar se recupera con incertidumbres menores que un factor dos. Hemos obtenido que las masas estelares de las galaxias luminosas compactas azules están en torno a diez mil millones de masas solares y que han sufrido un brote reciente de formación estelar que involucra entre un 5 y un 10% de la masa estelar. Comparando con las masas obtenidas para las galaxias elípticas, las masas estelares de las LBCGs son, en mediana, unas 7 veces menores. Las galaxias espirales cubren un rango amplio de masas, las de tipos tempranos tienen masas estelares similares a las de las elípticas, mientras que las espirales más azules tienen masas estelares similares a las de las LBCGs

Completion of the GOYA photometric survey

The Galaxy Origins and Young Assembly (goya) survey is designed to study the formation and evolution of 1 < z < 3 galaxies with the aim of learning on the epoch and the mechanisms by which galaxies assembled the bulk of their stars and acquired their present structure and dynamics. In 1998 goya proposed, and has since been guiding, the construction of the most ambitious of the common-user instruments for GranTeCan —the emir near-infrared multi-object spectrograph. In preparation for the exploitation of emir, we have conducted a deep near-infrared photometric survey, for sample selection and characterisation. Now that this research has reached its final stages, we provide here details on its current status and its finalisation plans. Overall, this survey has images of 0.5 square degrees of high-latitude sky to limiting ab magnitude Ks = 23.7 (5-¾, 100 aperture) and corresponding depths at U,B, V,R, I and J. The sample of sources obtained is being extended to include fields available to Gemini-S, since a recent collaboration with the Flamingos-2 Early Science Survey Team grants goya privileged access to this pioneering near-infrared multi-object spectrograph.Peer ReviewedPostprint (published version

Multiwavelength Properties of the X-ray Sources in the Groth-Westphal Strip Field

We summarize the multiwavelength properties of X-ray sources detected in the 80 ks XMM-Newton observation of the Groth-Westphal Strip. We find 23 XMM-Newton sources within the WFPC2 fields. Ten spectroscopic redshifts are available from the DEEP and CFRS projects and 4 of these show broad Mg II emission (type 1 AGNs). Two of those without any broad lines, nevertheless, have [NeV] emission which is an unambiguous signature of AGN activity, one of which is a narrow-line Seyfert 1 and the other a type 2 AGN. We have made near-infrared (NIR) spectroscopic observations using the Subaru OHS/CISCO spectrometer for five of the X-ray sources for which we found no indication of an AGN activity in the optical spectrum. We have detected H-alpha+[NII] emission in four of them. A broad H-alpha component and/or a large [NII]/H-alpha ratio is seen, suggestive of AGN activity. Nineteen sources have been detected in the Ks band and four of these are extremely red objects (I814-Ks>4). The optical counterparts for the majority of the X-ray sources are bulge-dominated with colors consistent with evolving elliptical galaxies, with starburst/AGN contamination. Assuming that the known local relations among the bulge luminosity,central velocity dispersion, and the mass of the central blackhole hold at about z=1, the AGN bolometric luminosity to Eddington luminosity ratio ranges from 0.3% to 10%. (abridged)Comment: 18 pages, 6 figures, accepted for publication in Astronomical Journa

Robust determination of the major merger fraction at z = 0.6 in Groth Strip

(Abridged) We measure the fraction of galaxies undergoing disk-disk major mergers (f_m) at intermediate redshifts (0.35 <= z < 0.85) by studying the asymmetry index A of galaxy images. Results are provided for B- and Ks-band absolute magnitude selected samples from the Groth strip in the GOYA photometric survey. Three sources of systematic error are carefully addressed: (i) we avoid morphological K-corrections, (ii) we measure asymmetries in artificially redshifted to z_d = 0.75 galaxies to lead with loss of morphological information with redshift, and (iii) we take into account the observational errors in z and A, that tend to overestimate the merger fraction, by maximum likelihood techniques. We find: (i) our data allow for a robust merger fraction to be provided for a single redshift bin centered at z=0.6. (ii) Merger fractions have low values: f_m = 0.045 for M_B <= -20 galaxies, and f_m = 0.031 for M_Ks <= -23.5 galaxies. And, (iii) failure to address the effects of the observational errors leads to overestimating f_m by factors of 10%-60%. Combining our results with those on literature, and parameterizing the merger fraction evolution as f_m(z) = f_m(0)(1+z)^m, we obtain that m = 2.9 +- 0.8, and f_m(0) = 0.012 +- 0.004$. Assuming a Ks-band mass-to-light ratio not varying with luminosity, we infer that the merger rate of galaxies with stellar mass M >= 3.5x10^10 M_Sun is R_m = 1.6x10^-4 Mpc^-3 Gyr^-1. When we compare with previous studies at similar redshifts, we find that the merger rate decreases when mass increases.Comment: Accepted for publication in ApJ. 11 pages, 7 figures, 3 tables. Formatted with emulateap

Evolution of Balmer jump selected galaxies in the ALHAMBRA survey

Extragalactic astronomy.-- et al.[Context]: Samples of star-forming galaxies at different redshifts have been traditionally selected via color techniques. The ALHAMBRA survey was designed to perform a uniform cosmic tomography of the Universe, and we here exploit it to trace the evolution of these galaxies. [Aims]: Our objective is to use the homogeneous optical coverage of the ALHAMBRA filter system to select samples of star-forming galaxies at different epochs of the Universe and study their properties. [Methods]: We present a new color-selection technique, based on the models of spectral evolution convolved with the ALHAMBRA bands and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 <z< 1.5. These galaxies are dubbed Balmer-jump Galaxies (BJGs). We applied the iSEDfit Bayesian approach to fit each detailed spectral energy distribution and determined star-formation rate (SFR), stellar mass, age, and absolute magnitudes. The mass of the halos in which these samples reside were found through a clustering analysis. [Results]: Five volume-limited BJG subsamples with different mean redshifts are found to reside in halos of median masses ∼10 M slightly increasing toward z = 0.5. This increment is similar to numerical simulations results, which suggests that we trace the evolution of an evolving population of halos as they grow to reach a mass of ∼10 at z = 0.5. The likely progenitors of our samples at z ∼ 3 are Lyman-break galaxies, which at z ∼ 2 would evolve into star-forming BzK galaxies, and their descendants in the local Universe are galaxies with luminosities of 1-3 L. Hence, this allows us to follow the putative evolution of the SFR, stellar mass, and age of these galaxies. [Conclusions]: From z ∼ 1.0 to z ∼ 0.5, the stellar mass of the volume-limited BJG samples changes almost not at all with redshift, suggesting that major mergers play a minor role in the evolution of these galaxies. The SFR evolution accounts for the small variations of stellar mass, suggesting that star formation and possible minor mergers are the main channels of mass assembly.P.T. and A.M.A. acknowledge support from FONDECYT 3140542 and FONDECYT 3160776, respectively. L.I., A.M.A., P.T., S.G., N.P. acknowledge support from Basal-CATA PFB-06/2007. E.J.A. acknowledges support from the Spanish Ministry for Economy and Competitiveness and FEDER funds through grant AYA2013-40611-P. A.F.S., V.J.M. and P.A.M. acknowledge partial financial support from the Spanish Ministry for Economy and Competitiveness and FEDER funds through grant AYA2013-48623-C2-2, and from Generalitat Valenciana through project PrometeoII 2014/060. B.A. acknowledges received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 656354.Peer Reviewe

J-PLUS: A wide-field multi-band study of the M15 globular cluster. Evidence of multiple stellar populations in the RGB

The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide field-of-view images in 12 narrow, intermediate and broad-band filters optimized for stellar photometry. Here we have applied J-PLUS data for the first time for the study of Galactic GCs using science verification data obtained for the very metal-poor GC M\,15. Our J-PLUS data provide low-resolution spectral energy distributions covering the near-UV to the near-IR, allowing us to search for MPs based on pseudo-spectral fitting diagnostics. J-PLUS CMDs are found to be particularly useful to search for splits in the sequences formed by the upper red giant branch (RGB) and asymptotic giant branch (AGB) stars. We interpret these split sequences as evidence for the presence of MPs. This demonstrates that the J-PLUS survey will have sufficient spatial coverage and spectral resolution to perform a large statistical study of GCs through multi-band photometry in the coming years.Comment: 11 pages, 11 figures. Accepted for publication @ A&

Dissecting quasars with the J-PAS narrow-band photometric survey

Nuclear Activity in Galaxies Across Cosmic Time, Proceedings of the conference held 7-11 October 2019 in Addis Ababa, Ethiopia. Edited by Mirjana Pović et al. Proceedings of the International Astronomical Union, Volume 356, pp. 12-16The J-PAS survey will soon start observing thousands of square degrees of the Northern Sky with its unique set of 56 narrow band filters covering the entire optical wavelength range, providing, effectively, a low resolution spectra for every object detected. Active galaxies and quasars, thanks to their strong emission lines, can be easily identified and characterized with J-PAS data. A variety of studies can be performed, from IFU-like analysis of local AGN, to clustering of high-z quasars. We also expect to be able to extract intrinsic physical quasar properties from the J-PAS pseudo-spectra, including continuum slope and emission line luminosities. Here we show the first attempts of using the QSFit software package to derive the properties for 22 quasars at 0.8 < z < 2 observed by the miniJPAS survey, the first deg2 of J-PAS data obtained with an interim camera. Results are compared with the ones obtained by applying the same software to SDSS quasar spectra.Financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709

J-PAS: Forecasts for dark matter - dark energy elastic couplings

We consider a cosmological model where dark matter and dark energy feature a coupling that only affects their momentum transfer in the corresponding Euler equations. We perform a fit to cosmological observables and confirm previous findings within these scenarios that favour the presence of a coupling at more than $3\sigma$. This improvement is driven by the Sunyaev-Zeldovich data. We subsequently perform a forecast for future J-PAS data and find that clustering measurements will permit to clearly discern the presence of an interaction within a few percent level with the uncoupled case at more than $10\sigma$ when the complete survey, covering $8500$ sq. deg., is considered. We found that the inclusion of weak lensing measurements will not help to further constrain the coupling parameter. For completeness, we compare to forecasts for DESI and Euclid, which provide similar discriminating power.Comment: 34 pages, 17 figures, added some clarifications and discussions, matches published versio

Galaxy clusters and groups in the ALHAMBRA Survey

We present a catalogue of 348 galaxy clusters and groups with $0.2<z<1.2$ selected in the 2.78 $deg^2$ ALHAMBRA Survey. The high precision of our photometric redshifts, close to $1\%$, and the wide spread of the seven ALHAMBRA pointings ensure that this catalogue has better mass sensitivity and is less affected by cosmic variance than comparable samples. The detection has been carried out with the Bayesian Cluster Finder (BCF), whose performance has been checked in ALHAMBRA-like light-cone mock catalogues. Great care has been taken to ensure that the observable properties of the mocks photometry accurately correspond to those of real catalogues. From our simulations, we expect to detect galaxy clusters and groups with both $70\%$ completeness and purity down to dark matter halo masses of $M_h\sim3\times10^{13}\rm M_{\odot}$ for $z<0.85$. Cluster redshifts are expected to be recovered with $\sim0.6\%$ precision for $z<1$. We also expect to measure cluster masses with $\sigma_{M_h|M^*_{CL}}\sim0.25-0.35\, dex$ precision down to $\sim3\times10^{13}\rm M_{\odot}$, masses which are $50\%$ smaller than those reached by similar work. We have compared these detections with previous optical, spectroscopic and X-rays work, finding an excellent agreement with the rates reported from the simulations. We have also explored the overall properties of these detections such as the presence of a colour-magnitude relation, the evolution of the photometric blue fraction and the clustering of these sources in the different ALHAMBRA fields. Despite the small numbers, we observe tentative evidence that, for a fixed stellar mass, the environment is playing a crucial role at lower redshifts (z$<$0.5).Comment: Accepted for publication in MNRAS. Catalogues and figures available online and under the following link: http://bascaso.net46.net/ALHAMBRA_clusters.htm

J-PLUS : a catalogue of globular cluster candidates around the M 81/M 82/NGC 3077 triplet of galaxies

Globular clusters (GCs) are proxies of the formation assemblies of their host galaxies. However, few studies exist targeting GC systems of spiral galaxies up to several effective radii. Through 12-band Javalambre Photometric Local Universe Survey (J-PLUS) imaging, we study the point sources around the M 81/M 82/NGC 3077 triplet in search of new GC candidates. We develop a tailored classification scheme to search for GC candidates based on their similarity to known GCs via a principal component analysis projection. Our method accounts for missing data and photometric errors. We report 642 new GC candidates in a region of 3.5 deg2 around the triplet, ranked according to their Gaia astrometric proper motions when available. We find tantalizing evidence for an overdensity of GC candidate sources forming a bridge connecting M 81 and M 82. Finally, the spatial distribution of the GC candidates (g − i) colours is consistent with halo/intra-cluster GCs, i.e. it gets bluer as they get further from the closest galaxy in the field. We further employ a regression-tree-based model to estimate the metallicity distribution of the GC candidates based on their J-PLUS bands. The metallicity distribution of the sample candidates is broad and displays a bump towards the metal-rich end. Our list increases the population of GC candidates around the triplet by threefold, stresses the usefulness of multiband surveys in finding these objects, and provides a testbed for further studies analysing their spatial distribution around nearby (spirals) galaxies