6,583 research outputs found
Study of ISM tracers in galaxies
We collected data for two samples of normal and interacting galaxies for a
total of 2953 galaxies having fluxes in one or more of the following wavebands:
FIR, 21 cm line, CO(1-0) lines and soft X-ray. The large set of data obtained
allowed us to revisit some of the already known relations between the different
tracers of the interstellar medium (ISM), such as the link between the FIR flux
and the CO line emission, the relation between X-ray emission and the blue or
FIR luminosity. The relation lacking from observations for early-type galaxies
has been discussed and explained in detail in the frame of a suitable
theoretical model, obtained by coupling chemo-dynamical N-body simulations with
a dusty spectrophotometric code of population synthesis.Comment: 2 pages, o appear in the Proceedings of the Conf. "From Stars to
Galaxies: Building the Pieces to Build Up the Universe", Vallenari et al.
eds., ASP Conf. Serie
Hurricane Beulah Photograph scrapbook
Scrapbook of black and white photographs taken by Merlin E. Rekward, border patrol agent when Hurricane Beulah made landfall. Detailed record can be located here.https://scholarworks.utrgv.edu/beulah/1000/thumbnail.jp
Complexity reduction of astrochemical networks
We present a new computational scheme aimed at reducing the complexity of the
chemical networks in astrophysical models, one which is shown to markedly
improve their computational efficiency. It contains a flux-reduction scheme
that permits to deal with both large and small systems. This procedure is shown
to yield a large speed-up of the corresponding numerical codes and provides
good accord with the full network results. We analyse and discuss two examples
involving chemistry networks of the interstellar medium and show that the
results from the present reduction technique reproduce very well the results
from fuller calculations.Comment: 9 pages, 7 figures, accepted for publication in Monthly Notices of
the Royal Astronomical Society Main Journa
UV slope of z3 bright () Lyman-break galaxies in the COSMOS field
We analyse a unique sample of 517 bright () LBGs at redshift
z3 in order to characterise the distribution of their UV slopes
and infer their dust extinction under standard assumptions. We exploited
multi-band observations over 750 arcmin of the COSMOS field that were
acquired with three different ground-based facilities: the Large Binocular
Camera (LBC) on the Large Binocular Telescope (LBT), the Suprime-Cam on the
SUBARU telescope, and the VIRCAM on the VISTA telescope (ULTRAVISTA DR2). Our
multi-band photometric catalogue is based on a new method that is designed to
maximise the signal-to-noise ratio in the estimate of accurate galaxy colours
from images with different point spread functions (PSF). We adopted an improved
selection criterion based on deep Y-band data to isolate a sample of galaxies
at to minimise selection biases. We measured the UV slopes ()
of the objects in our sample and then recovered the intrinsic probability
density function of values (PDF()), taking into account the
effect of observational uncertainties through detailed simulations. The
galaxies in our sample are characterised by mildly red UV slopes with
throughout the enitre luminosity range that is probed by
our data (). The resulting dust-corrected
star formation rate density (SFRD) is , corresponding to a contribution of about 25% to the
total SFRD at z3 under standard assumptions. Ultra-bright LBGs at match the known trends, with UV slopes being redder at decreasing redshifts,
and brighter galaxies being more highly dust extinct and more frequently
star-forming than fainter galaxies. [abridged]Comment: Matched to journal version. 11 pages, 13 figures, Astronomy &
Astrophysics in pres
Outcome of children with panarteritis nodosa: a series of 30 cases
International audiencepas de résum
Euclid preparation: XXV. The Euclid Morphology Challenge: Towards model-fitting photometry for billions of galaxies
ArtÃculo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMThe European Space Agency's Euclid mission will provide high-quality imaging for about 1.5 billion galaxies. A software pipeline to automatically process and analyse such a huge amount of data in real time is being developed by the Science Ground Segment of the Euclid Consortium; this pipeline will include a model-fitting algorithm, which will provide photometric and morphological estimates of paramount importance for the core science goals of the mission and for legacy science. The Euclid Morphology Challenge is a comparative investigation of the performance of five model-fitting software packages on simulated Euclid data, aimed at providing the baseline to identify the best-suited algorithm to be implemented in the pipeline. In this paper we describe the simulated dataset, and we discuss the photometry results. A companion paper is focussed on the structural and morphological estimates. We created mock Euclid images simulating five fields of view of 0.48 deg2 each in the IE band of the VIS instrument, containing a total of about one and a half million galaxies (of which 350 000 have a nominal signal-to-noise ratio above 5), each with three realisations of galaxy profiles (single and double Sérsic, and 'realistic' profiles obtained with a neural network); for one of the fields in the double Sérsic realisation, we also simulated images for the three near-infrared YE, JE, and HE bands of the NISP-P instrument, and five Rubin/LSST optical complementary bands (u, g, r, i, and z), which together form a typical dataset for an Euclid observation. The images were simulated at the expected Euclid Wide Survey depths. To analyse the results, we created diagnostic plots and defined metrics to take into account the completeness of the provided catalogues, as well as the median biases, dispersions, and outlier fractions of their measured flux distributions. Five model-fitting software packages (DeepLeGATo, Galapagos-2, Morfometryka, ProFit, and SourceXtractor++) were compared, all typically providing good results. Of the differences among them, some were at least partly due to the distinct strategies adopted to perform the measurements. In the best-case scenario, the median bias of the measured fluxes in the analytical profile realisations is below 1% at a signal-to-noise ratio above 5 in IE, and above 10 in all the other bands; the dispersion of the distribution is typically comparable to the theoretically expected one, with a small fraction of catastrophic outliers. However, we can expect that real observations will prove to be more demanding, since the results were found to be less accurate for the most realistic realisation. We conclude that existing model-fitting software can provide accurate photometric measurements on Euclid datasets. The results of the challenge are fully available and reproducible through an online plotting too
- …