2,496 research outputs found
J-PLUS: analysis of the intracluster light in the Coma cluster
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 , 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.Comment: 10 pages, 3 figures, 1 table. Accepted for publication in A&
J-PLUS: Identification of low-metallicity stars with artificial neural networks using SPHINX
We present a new methodology for the estimation of stellar atmospheric
parameters from narrow- and intermediate-band photometry of the Javalambre
Photometric Local Universe Survey (J-PLUS), and propose a method for target
pre-selection of low-metallicity stars for follow-up spectroscopic studies.
Photometric metallicity estimates for stars in the globular cluster M15 are
determined using this method. By development of a neural-network-based
photometry pipeline, we aim to produce estimates of effective temperature,
, and metallicity, [Fe/H], for a large subset of stars in the
J-PLUS footprint. The Stellar Photometric Index Network Explorer, SPHINX, is
developed to produce estimates of and [Fe/H], after training on a
combination of J-PLUS photometric inputs and synthetic magnitudes computed for
medium-resolution (R ~ 2000) spectra of the Sloan Digital Sky Survey. This
methodology is applied to J-PLUS photometry of the globular cluster M15.
Effective temperature estimates made with J-PLUS Early Data Release photometry
exhibit low scatter, \sigma() = 91 K, over the temperature range
4500 < (K) < 8500. For stars from the J-PLUS First Data Release
with 4500 < (K) < 6200, 85 3% of stars known to have [Fe/H]
<-2.0 are recovered by SPHINX. A mean metallicity of [Fe/H]=-2.32 0.01,
with a residual spread of 0.3 dex, is determined for M15 using J-PLUS
photometry of 664 likely cluster members. We confirm the performance of SPHINX
within the ranges specified, and verify its utility as a stand-alone tool for
photometric estimation of effective temperature and metallicity, and for
pre-selection of metal-poor spectroscopic targets.Comment: 18 pages, 12 figure
Rules, Standards, and the Internal Point of View
Large scale structure and cosmolog
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&
The GALANTE photometric survey of the northern Galactic plane: Project description and pipeline
The GALANTE optical photometric survey is observing the northern Galactic
plane and some adjacent regions using seven narrow- and intermediate-filters,
covering a total of 1618 square degrees. The survey has been designed with
multiple exposure times and at least two different air masses per field to
maximize its photometric dynamic range, comparable to that of Gaia, and ensure
the accuracy of its photometric calibration. The goal is to reach at least 1%
accuracy and precision in the seven bands for all stars brighter than AB
magnitude 17 while detecting fainter stars with lower values of the
signal-to-noise ratio.The main purposes of GALANTE are the identification and
study of extinguished O+B+WR stars, the derivation of their extinction
characteristics, and the cataloguing of F and G stars in the solar
neighbourhood. Its data will be also used for a variety of other stellar
studies and to generate a high-resolution continuum-free map of the H{\alpha}
emission in the Galactic plane. We describe the techniques and the pipeline
that are being used to process the data, including the basis of an innovative
calibration system based on Gaia DR2 and 2MASS photometry.Comment: 18 pages, accepted for publication in MNRA
The study of soil, hydrological, erosion and vegetation processes following wildfire in the Colmeal study area, central Portugal
The EROSFIRE-II project (PTDC/AGR-CFL/70968/2006) has as overall aim to
predict soil erosion risk in recently burnt forest areas, including following common
post-fire forest management practices. Although the project’s main focus is on onsite erosion processes, also the export of sediments out of small catchments is
addressed. To this end, a study area of about 60 ha located near to the village of
Colmeal (municipality of Góis, central Portugal) was instrumented extensively
following a wildfire during August 2008, and has been monitored intensively
afterwards.(...
J-PLUS: Detecting and studying extragalactic globular clusters -- the case of NGC 1023
Extragalactic globular clusters (GCs) are key objects for studying the
formation and evolution of galaxies. The arrival of wide-field surveys such as
the Javalambre Photometric Local Universe Survey (J-PLUS) offers new
possibilities for the study of GCs. Nevertheless, GCs are not detected a priori
by the data reduction pipeline of J-PLUS and, due to its pixel scale, the
standard techniques of GCs detection are challenged. To fill this gap, we
develop a semi-automatic pipeline to detect GCs in J-PLUS that can also be
adapted to similar surveys. As a case study, we use data from the S0 galaxy NGC
1023 and we also study the stellar population content of GC candidates in the
galaxy. To detect GCs, our methodology is based on Source Extractor and does
not require a previous filtering or modelling of the host galaxy. We study
colors and perform spectral energy distribution (SED) analysis on our final GC
candidate catalog to obtain stellar population parameters. In NGC 1023,
GCFinder identifies 523 GC candidates. We observe evidence of color bimodality
in a few broad-band colors but not on narrow-band colors. The SED analysis
reveals a clear metallicity bimodality and we observe that narrow-band filters
are very useful to constrain metallicities. We also identified a broad
age-metallicity relation as well as a wide metallicity distribution that are
evidence that NGC 1023 experienced accretion events in the past. It is the
first time this kind of study is performed with J-PLUS data. By detecting GC
candidates in wide-field images without modeling the light of the galaxy,
GCFinder becomes considerably faster, at a marginal loss of centrally-located
GC candidates of about 7 percent. As GCFinder is entirely based on Source
Extractor, it could be easily incorporated into automated software handling
wide-field surveys.Comment: 21 pages, 19 figures, submitted to A&
J-PLUS: measuring emission line fluxes in the nearby universe
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 deg2 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.Comment: 13 pages, 8 figures, 3 tables. Submitted to Astronomy and
Astrophysics. Comments are welcom
- …