Publicaciones: Científicas

Publicaciones: Científicas

The intracluster light (ICL) is a luminous component of galaxy clusters composed of stars that are gravitationally bound to the cluster potential but do not belong to the individual galaxies. Previous studies of the ICL have shown that its formation and evolution are intimately linked to the evolutionary stage of the cluster. Thus, the analysis of the ICL in the Coma cluster will give insights into the main processes driving the dynamics in this highly complex system. Using a recently developed technique, we measure the ICL fraction in Coma at several wavelengths, using the J-PLUS unique filter system. The combination of narrow- and broadband filters provides valuable information on the dynamical state of the cluster, the ICL stellar types, and the morphology of the diffuse light. We use the Chebyshev-Fourier Intracluster Light Estimator (CICLE) to disentangle the ICL from the light of the galaxies, and to robustly measure the ICL fraction in seven J-PLUS filters. We obtain the ICL fraction distribution of the Coma cluster at different optical wavelengths, which varies from ~ 7%-21%, showing the highest values in the narrowband filters J0395, J0410, and J0430. This ICL fraction excess is distinctive pattern recently observed in dynamically active clusters (mergers), indicating a higher amount of bluer stars in the ICL compared to the cluster galaxies. Both the high ICL fractions and the excess in the bluer filters are indicative of a merging state. The presence of younger/lower-metallicity stars the ICL suggests that the main mechanism of ICL formation for the Coma cluster is the stripping of the stars in the outskirts of infalling galaxies and, possibly, the disruption of dwarf galaxies during past/ongoing mergers.

Publicación completa >>

GALANTE is an optical photometric survey with seven intermediate/narrow filters that has been covering the Galactic Plane since 2016 using the Javalambre T80 and Cerro Tololo T80S telescopes. The P.I.s of the northern part (GALANTE NORTE) are Emilio J. Alfaro and Jes\'us Ma\'iz Apell\'aniz. and the P.I. of the southern part (GALANTE SUR) is Rodolfo H. Barb\'a. The detector has a continuous 1.4 degr x 1.4 degr field of view with a sampling of 0.55"/pixel and the seven filters are optimized to detect obscured early-type stars. The survey includes long, intermediate, short, and ultrashort exposure times to reach a dynamical range close to 20 magnitudes, something never achieved for such an optical project before. The characteristics of GALANTE allow for a new type of calibration scheme using external Gaia, Tycho-2, and 2MASS data that has already led to a reanalysis of the sensitivity of the Gaia G filter. We describe the project and present some early results. GALANTE will identify the majority of the early-type massive stars within several kpc of the Sun and measure their amount and type of extinction. It will also map the Halpha nebular emission, identify emission-line stars, and do other studies of low- and intermediate-mass stars.

Publicación completa >>

We have observed the field of GRB 180914B (Ursi et al., GCN 23226; Verrecchia et al., GCN 23231; Bissaldi et al. GCN 23232; Ursi et al., GCN 23236) with the 0.8m T80 telescope of the Javalambre Astrophysical Observatory (Teruel, Spain). The observation consisted of 12x300s i-band exposures, each covering the complete LAT error box. The exposures started at 22:03:46 UT of the 15th September, 27.68 hr after the burst. The counterpart identified by Zheng & Filippenko (GCN 23237) and Troja et al. (GCN 23238) is well detected in the individual images. Photometry of the first epoch, as compared with SDSS reference stars yields i(AB)=18.84+/-0.03. Comparing with the RATIR photometry (roja et al. GCN 23238), our photometry implies a decay rate of alpha ~ -1.9 (where F_nu ~ t^alpha), indicating that the afterglow has possibly entered a post-jet-break regime evolution.

Publicación completa >>

The study of Cataclysmic Variables (CVs) is crucial to test our understanding of binary evolution and its application to many astrophysical phenomena, such as short gamma-ray bursts, X-ray transients and, more important, Supernovae Ia, our yardsticks for measuring distances. Yet, the predicted major component of the present-day CV population, the so-called "period bouncers" (CVs containing a white dwarf and a degenerate donor), has not been detected, highlighting a major discrepancy between theory and observations. We present here CHiCaS, the Compact binary HIgh CAdence Survey, which will perform three hours of uninterrupted time series photometry over 136 square degrees of the sky with JAST/T80Cam. By the end of next year, this program will deliver one minute cadence lightcurves for ≃2.5≃2.5 million objects as faint as g≃21.5g≃21.5, along with full colour information. Via detection of their eclipses, CHiCaS will finally, and unambiguously identify the predicted large population of period bouncers. The identification of the missing population will provide an observational support for the current models for the mechanisms of angular momentum loss in compact binaries, which also describe the evolution of all kind of binaries. CHiCaS will also offer a complete and unbiased view into the short term variability of thousands of binaries, eclipsing systems, pulsating stars and CVs in the period gap, which will allow to improve our knowledge of these objects and to carry out additional tests on CV evolution.

Publicación completa >>

Cataclysmic Variables (CVs) are one of the best classes to test our understanding of the evolution of compact, interacting binaries: they are numerous, relatively bright, and both stellar components are structurally simple. Nonetheless, our recent results from a large HST program (Pala et al. 2017) have highlighted a number of discrepancies between current population models and observations. Only once these discrepancies are resolved we can trust the theoretical models to be sensibly applied to more complex systems, such as black hole binaries, X-ray transients or SN Ia progenitors.In particular, one of the most striking disagreements is the lack of period bouncers, i.e. old CVs in which the companions have been eroded down to brown dwarf masses. These systems are predicted to make up for ≃ 70% of the observed CV population, yet very few have been identified so far, suggesting that the physical mechanisms driving CV evolution (such as the mechanisms of angular momentum loss, the common envelope phase and/or the response of the companions to the mass loss) are still not completely understood. For this reason we have started a high cadence photometric survey using JAST/T80Cam aimed to find these elusive systems and we present here the preliminary results from this observing program.

Publicación completa >>

We observed the field of the Swift-BAT GRB 180720B (Siegel et al. GCN 22973), detected also by Fermi-LAT (Bissaldi et al. GCN 22980), with the 0.8m telescope of the Observatorio Astrofisico de Javalambre (Teruel, Spain). Observations consisted of a series of 3x300 s griz exposures, starting at 01:12:55 UT (10.85 hr after the GRB trigger). The afterglow is clearly detected at a position consistent with the one reported by Martone et al. (GCN 22976). We measure a magnitude of r(AB) = 17.77+/- 0.05 mag at an average time of 01:37:14 UT (11.26 hr after the GRB trigger), as compared to nearby SDSS stars.

Publicación completa >>

The Javalambre Survey Telescope (JST/T250) is a wide-field 2.6 m telescope ideal for carrying out large sky photometric surveys from the Javalambre Astrophysical Observatory in Teruel, Spain. The most immediate goal of JST is to perform J-PAS, a survey of several thousands square degrees of the Northern sky in 59 optical bands, 54 of them narrow (˜ 145 Å FWHM) and contiguous. J-PAS will provide a low resolution photo-spectrum for every pixel of the sky, hence promising crucial breakthroughs in Cosmology and Astrophysics. J-PAS will be conducted with JPCam, a camera with a mosaic of 14 CCDs of 9.2k × 9.2k pix, more than 1200 Mpix and an effective FoV of 4.3 deg2 . Before JPCam is on telescope, the project will work in 2018 with an interim camera, JPAS-Pathfinder, with a reduced FoV of ˜ 0.6 × 0.6 deg2 to perform commissioning and the first JST science. This paper presents the current status and performance of the JST telescope, describing the commissioning and first science of the JPAS-Pathfinder at JST.

Publicación completa >>

In the present paper we aim to validate a methodology designed to extract the Halpha emission line flux from J-PLUS photometric data. J-PLUS is a multi narrow-band filter survey carried out with the 2 deg^2 field of view T80Cam camera, mounted on the JAST/T80 telescope in the OAJ, Teruel, Spain. The information of the twelve J-PLUS bands, including the J0660 narrow-band filter located at rest-frame Halpha, is used over 42 deg2 to extract de-reddened and [NII] decontaminated Halpha emission line fluxes of 46 star-forming regions with previous SDSS and/or CALIFA spectroscopic information. The agreement of the inferred J-PLUS photometric Halpha fluxes and those obtained with spectroscopic data is remarkable, with a median comparison ratio R = 1.05 +- 0.25. This demonstrates that it is possible to retrieve reliable Halpha emission line fluxes from J-PLUS photometric data. With an expected area of thousands of square degrees upon completion, the J-PLUS dataset will allow the study of several star formation science cases in the nearby universe, as the spatially resolved star formation rate of nearby galaxies at z < 0.015, and how it is influenced by the environment, morphology or nuclear activity. As an illustrative example, the close pair of interacting galaxies NGC3994 and NGC3995 is analyzed, finding an enhancement of the star formation rate not only in the center, but also in outer parts of the disk of NGC3994.

Publicación completa >>

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.

Publicación completa >>

The spatial variations of stellar population properties within a galaxy are intimately related to their formation process. Therefore, spatially resolved studies of galaxies are essential to uncover their formation and assembly. The Javalambre Photometric Local Universe Survey (J-PLUS) is a dedicated multi-filter designed to observed ~8500 deg^2 using twelve narrow-, intermediate- and broad-band filters in the optical range. In this study, we test the potential of the multi-filter observation carried out with J-PLUS to investigate the properties of spatially-resolved nearby galaxies. We present detailed 2D maps of stellar population properties (age, metallicity, extinction, and stellar mass surface density) for two early-type galaxies observed in both, J-PLUS and CALIFA surveys: NGC 5473 and NGC 5485. Radial structures are also compared and luminosity- and mass-weighted profiles are derived. We use MUFFIT to process the J-PLUS observations, and two different techniques (STARLIGHT and STECKMAP) to analyze IFU CALIFA data. We demonstrate that this novel technique delivers radial stellar population gradients in good agreement with the IFU technique CALIFA/STECKMAP although comparison of the absolute values reveals the existence of intrinsic systematic differences. Radial stellar population gradients differ when CALIFA/STARLIGHT methodology is used. Age and metallicity radial profiles derived from J-PLUS/MUFFIT are very similar when luminosity- or mass-weighted properties are used, suggesting that the contribution of a younger component is small. Comparison between the three methodologies reveals some discrepancies suggesting that the specific characteristics of each method causes important differences. We conclude that the ages, metallicities and extinction derived for individual galaxies not only depend on the chosen models but also depend on the method used.

Publicación completa >>

We aim to use multi-band imaging from the Phase-3 Verification Data of the J-PLUS survey to derive accurate photometric redshifts (photo-z) and look for potential new members in the surroundings of the nearby galaxy clusters A2589 (z=0.0414) & A2593 (z=0.0440), using redshift probability distribution functions. The ultimate goal is to demonstrate the usefulness of a 12-band filter system in the study of large-scale structure in the local universe. We present an optimized pipeline for the estimation of photo-z in clusters of galaxies. We tested our photo-z with a sample of 296 spectroscopically confirmed cluster members with a magnitude of = 16.6 and redshift =0.041. The combination of seven narrow and five broadband filters with a typical photometric-depth of r<21.5 provides dz/(1+z)=0.01 photo-z estimates. A precision of dz/(1+z)=0.005 is obtained for the 177 galaxies brighter than magnitude r<17. To foresee the precision beyond the spectroscopic sample, we designed a set of simulations in which real cluster galaxies are modeled and reinjected inside the images at different signal-to-noise. A precision of dz/(1+z)=0.02 and dz/(1+z)=0.03 is expected at = 18-22, respectively. Complementarily, we used SDSS/DR12 data to derive photo-z estimates for the same galaxy sample, demonstrating that the wavelength-resolution of the J-PLUS can double the precision achieved by SDSS for galaxies with a high S/N. We find as much as 170 new candidates across the entire field. The spatial distribution of these galaxies may suggest an overlap between the systems with no evidence of a clear filamentary structure connecting the clusters. These preliminary results show the potential of J-PLUS data to revisit membership of groups and clusters from nearby galaxies, important for the determination of luminosity and mass functions and environmental studies at the intermediate and low-mass regime.

Publicación completa >>

Our goal is to morphologically classify the sources identified in the images of the J-PLUS early data release (EDR) into compact (stars) or extended (galaxies) using a suited Bayesian classifier. J-PLUS sources exhibit two distinct populations in the r-band magnitude vs. concentration plane, corresponding to compact and extended sources. We modelled the two-population distribution with a skewed Gaussian for compact objects and a log-normal function for the extended ones. The derived model and the number density prior based on J-PLUS EDR data were used to estimate the Bayesian probability of a source to be star or galaxy. This procedure was applied pointing-by-pointing to account for varying observing conditions and sky position. Finally, we combined the morphological information from g, r, and i broad bands in order to improve the classification of low signal-to-noise sources. The derived probabilities are used to compute the pointing-by-pointing number counts of stars and galaxies. The former increases as we approach to the Milky Way disk, and the latter are similar across the probed area. The comparison with SDSS in the common regions is satisfactory up to r ~ 21, with consistent numbers of stars and galaxies, and consistent distributions in concentration and (g - i) colour spaces. We implement a morphological star/galaxy classifier based on PDF analysis, providing meaningful probabilities for J-PLUS sources to one magnitude deeper (r ~ 21) than a classical boolean classification. These probabilities are suited for the statistical study of 150k stars and 101k galaxies with 15 < r < 21 present in the 31.7 deg2 of the J-PLUS EDR. In a future version of the classifier, we will include J-PLUS colour information from twelve photometric bands.

Publicación completa >>

J-PLUS is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern hemisphere from the dedicated JAST/T80 telescope at the Observatorio Astrofísico de Javalambre. T80Cam is a 2 sq.deg field-of-view camera mounted on this 83cm-diameter telescope, and is equipped with a unique system of filters spanning the entire optical range. This filter system is a combination of broad, medium and narrow-band filters, optimally designed to extract the rest-frame spectral features (the 3700-4000 Å Balmer break region, H_delta, Ca H+K, the G-band, the Mgb and Ca triplets) that are key to both characterize stellar types and to deliver a low-resolution photo-spectrum for each pixel of the sky observed. With a typical depth of AB ~ 21.25 mag per band, this filter set thus allows for an indiscriminate and accurate characterization of the stellar population in our Galaxy, it provides an unprecedented 2D photo-spectral information for all resolved galaxies in the local universe, as well as accurate photo-z estimates (Delta_z~ 0.01-0.03) for moderately bright (up to r ~ 20 mag) extragalactic sources. While some narrow band filters are designed for the study of particular emission features ([OII]/lambda3727, H_alpha/lambda6563) up to z < 0.015, they also provide well-defined windows for the analysis of other emission lines at higher redshifts. As a result, J-PLUS has the potential to contribute to a wide range of fields in Astrophysics, both in the nearby universe (Milky Way, 2D IFU-like studies, stellar populations of nearby and moderate redshift galaxies, clusters of galaxies) and at high redshifts (ELGs at z~0.77, 2.2 and 4.4, QSOs, etc). With this paper, we release ~36 deg² of J-PLUS data, containing about 1.5 x 10^5 stars and 10^5 galaxies at r<21 mag.

Publicación completa >>

We present a morphological classification of J-PLUS EDR sources into compact (i.e. stars) and extended (i.e. galaxies). Such classification is based on the Bayesian modelling of the concentration distribution, including observational errors and magnitude + sky position priors. We provide the star / galaxy probability of each source computed from the gri images. The comparison with the SDSS number counts support our classification up to r 21. The 31.7 deg² analised comprises 150k stars and 101k galaxies.

Publicación completa >>

Located at the Observatorio Astrofísico de Javalambre, the ’’Javalambre Auxiliary Survey Telescope’’ is an 80cm telescope with a unvignetted 2 square degrees field of view. The telescope is equipped with T80Cam, a camera with a large format CCD and two filter wheels which can host, at any given time, 12 filters. The telescope has been designed to provide optical quality all across the field of view, which is achieved with a field corrector. In this talk, I will review the commissioning of the telescope. The optical performance in the centre of the field of view has been tested with lucky imaging technique, providing a telescope PSF of 0.4’’, which is close to the one expected from theory. Moreover, the tracking of the telescope does not affect the image quality, as it has been shown that stars appear round even in exposures of 10minutes obtained without guiding. Most importantly, we present the preliminary results of science verification observations which combine the two main characteristics of this telescope: the large field of view and the special filter set.

Publicación completa >>

In the framework of the Science Verification Phase of T80Cam of the 83cm Javalambre Auxiliary Survey Telescope (JAST80) located at the Observatorio Astrofísico de Javalambre (OAJ), Teruel, Spain, a program was proposed to study the variability of RR Lyrae stars, as well as other variable sources, belonging to the Galactic globular cluster M15. The observations were carried out on different epochs (almost a dozen different nights along a ~4 months period) using the complete set of 12 filters, centered at the optical spectral range, that are being devoted to the exectuion of the ongoing Javalambre Photometric Local Universe Survey (J-PLUS). One of the main goals is the characterization of the variability of the spectral energy distribution of RR Lyrae stars along their pulsation. This will be used to define methods to detect these type of variables in J-PLUS and J-PLUS. Preliminarly results are presented here.

Publicación completa >>

M33, the Triangulum Galaxy, is a spiral galaxy in the Local Group. Given its brightness and its vicinity with Andromeda Galaxy (M31), it is one of the best studied objects of the Northern hemisphere. In this poster, we present observations carried out with the JAST/T80 at the Observatorio Astrofísico de Javalambre. The extraordinary field of view of this telescope allows us to study the stellar populations of the galaxy with a single observation. Moreover, repeated observations have provided us the possibility to follow a variety of variable stars, among them the nova ASASSN-15th.

Publicación completa >>

Classical novae have been studied for over a century but the relation between these explosions and their host systems is still far from complete. In this talk, I review a project aimed at building a statistically significant sample of old nova systems and I analyse the role of future narrow-band surveys in the search for these objects.

Publicación completa >>

It is widely accepted that large disk galaxies derive from the merger and accretion of many smaller subsystems. However, it is less clear how low-mass spiral galaxies fit into this picture. The best way to answer this question is to study the nearest example of a dwarf spiral galaxy, M 33. We propose to perform a detailed photometric analysis of the resolved and unresolved stellar population of M 33 using data from the Javalambre Photometric Local Universe Survey (J-PLUS). Using a set of 12 broad-, intermediate- and narrow-band filters, J-PLUS will cover a wavelength range between 330-1000 nm, reaching magnitudes of r ~ 22. We will take advantage of the IFU-like capabilities of the survey to determine the properties of the spatially resolved and unresolved components of the galaxy. In particular, we will perform a 2-D analysis of the underlying population as well as a detailed study of M 33 star cluster system. Spectral fitting diagnostics of the resolved and unresolved populations will allow us to determine ages, metallicities and masses of the galactic disk, spheroidal components and cluster system. We will analyze two regions covering a total area of 3.2 deg². One field will be centered on M 33 covering the disk and the outskirts. A second field will cover the line connecting M 33 with M 31 to map the stellar substructure surrounding M 33. This study will provide key insights into the star formation history of low-mass galaxies as well as place M 33 within the context of galaxy formation process.

Publicación completa >>

The Observatorio Astrofisico de Javalambre is equipped with two wide field telescopes with a combination of broad and narrow band filters. The filters of the Javalambre Auxiliary Survey Telescope (80cm diameter) have been designed for stellar classification while the filters of the Javalambre Survey Telescope (2.5m diameter) have been designed for high accuracy determination of photometric redshifts of galaxies. In this article, I explain how the same filter set can also be used to efficiently recover cataclysmic variables and separate them from other objects (like quasars) and even tell their type. The observations to be carried out at the Observatorio Astrofisico de Javalambre will provide the best magnitude limited complete saple of cataclysmic variables to date.

Publicación completa >>

White dwarfs are the end state of all main sequence stars less massive than 8M_sun, which means that 98% of all stars will end up as white dwarfs. First and foremost, J-PAS will allow us to discover many new white dwarfs. It will go deeper than SDSS; most of SDSS spectroscopically confirmed white dwarfs have a magnitude below 20.5, while J-PAS will be complete (5σ detections) down to 22.5 in each filter. So we should see white dwarfs 2.5 times farther than SDSS and therefore the total volume will be 2.5³ - 1 = 14.6 times larger. By definition every object in J-PAS will be spectroscopically observed, while in SDSS only chosen objects had their spectra taken, so our white dwarf sample will also be much more complete than SDSS. We expect to increase the total number of white dwarfs from approximately 20,000 to 300,000. Among our goals are the study of the white dwarf luminosity function and the mass distribution.

Publicación completa >>

The Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) is a new astronomical facility dedicated to mapping the observable Universe in 59 colors, and will produce high-quality images and an unique spectral resolution over the 8000 deg². It will consist of two telescopes. One of 2.5-m (J-PAS) and another of 0.8-m (J-PLUS, mainly for calibrations). The former will have a dedicated 1.2-G pixel survey camera (containing an array of 14 CCDs) with a FoV of 5 deg^2. It is planned to take 4-5 years and is expected to map the above area to a 5σ magnitude depth for point sources equivalent to i˜23.3 over an aperture of 2 arcsec². The J-PAS filter system consists of 54 contiguous narrow band filters of 100-Å FWHM, from 3,500 to 10,000Å. To those filters 2 broad-band ones will be at the extremes, UV and IR, plus 3 SDSS g, r, and i filters. J-PLUS, on the other hand, comprise 12 filters, including g, r, i and z SDSS ones. Though about 2,500 PNe (confirmed spectroscopically) are known in the Galaxy, only about 20 objects have been identified as halo PNe. They were found from their location, kinematics and chemistry. Halo PNe are able to reveal precious information for the study of low- and intermediate-mass star evolution and the early chemical conditions of the Galaxy. The characteristic low continuum and intense line emissions of PNe make them good objects to be searched for by J-PAS. For instance, the halo PNe BoBn 1, DdDm 1 and PS 1, located somewhere between 11 and 24 kpc from the Sun, have B magnitudes of 16, 14 and 13.4, respectively. Such values are easily encompassed by J-PAS, given the typical limit magnitude of the survey. Because of the low number of halo PNe detected so far, we are developing tools to find these objects by using J-PAS/J-PLUS, and planning a follow-up study for any possible candidate identified by the survey. Color magnitudes diagram able to separate PNe from other strong line emission objects are being explored by the group and results are discussed in this contribution.

Publicación completa >>