160 research outputs found
Birds in Coastal and Marine Environments
In Costa Rican coastal and marine environments (e.g., estuaries, mud- flats, islands, open ocean) 96 bird species have been recorded, 11% of the total avifauna in the country. This high diversity is primarily explained by the complex topography of the coasts, the large variety of habitats available for coastal and marine birds, and Isla del Coco, a volcanic island that includes a particular marine avifauna. The Pacific coast, including Isla del Coco, possesses a much higher diversity of birds (93 species) than the Caribbean coast (54 species). This difference is likely explained by higher fluctuation in tides, larger extension, and greater topographical complexity on the Pacific coast. There are only 15 coastal or marine birds that reproduce (but not exclusively) in the country. From a conservation perspective, coastal and marine birds have received little attention in Costa Rica. Consequently, contamination, caused by pesticides, sewage, and solid trash, and habitat destruction, due to the construction of tourist infrastructure, seriously threaten the coastal and marine avifauna in Costa Rica.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí
Active galactic nuclei, gravitational redshifts, and cosmological tensions
Gravitational redshift is a classical effect of Einstein's General
Relativity, already measured in stars, quasars and clusters of galaxies. We
here identify the signature of gravitational redshift in the emission lines of
active galaxies due to supermassive black holes and discuss their impact on
cosmological inference from type Ia supernovae. Firstly, from the full width at
half maximum of lines of 75 Seyfert type I galaxies of the AGN
Black Hole Mass Database, we derive a gravitational redshift . Expanding this analysis to 86755 quasars from DR14 of
SDSS we have a mean value . Then, by comparing
the redshifts of 34 lines measured at the central and outer regions of LINER
galaxies in the SAMI survey we obtain .
These numbers are compatible with central black holes of solar
masses and broad line regions of ~pc. For non-AGN galaxies the
gravitational redshift is compatible with zero and, as they constitute most of
SNe Ia host galaxies, the impact on the cosmological parameters is negligible.Comment: 5 pages, 5 figure
Subhalo abundance matching and assembly bias in the EAGLE simulation
Subhalo abundance matching (SHAM) is a widely used method to connect galaxies with dark matter structures in numerical simulations. SHAM predictions agree remarkably well with observations, yet they still lack strong theoretical support. We examine the performance, implementation, and assumptions of SHAM using the ‘Evolution and Assembly of Galaxies and their Environment’ (EAGLE) project simulations. We find that Vrelax, the highest value of the circular velocity attained by a subhalo while it satisfies a relaxation criterion, is the subhalo property that correlates most strongly with galaxy stellar mass (Mstar). Using this parameter in SHAM, we retrieve the real-space clustering of EAGLE to within our statistical uncertainties on scales greater than 2 Mpc for galaxies with 8.77 < log 10(Mstar[M⊙]) < 10.77. Conversely, clustering is overestimated by 30 per cent on scales below 2 Mpc for galaxies with 8.77 < log 10(Mstar[M⊙]) < 9.77 because SHAM slightly overpredicts the fraction of satellites in massive haloes compared to EAGLE. The agreement is even better in redshift space, where the clustering is recovered to within our statistical uncertainties for all masses and separations. Additionally, we analyse the dependence of galaxy clustering on properties other than halo mass, i.e. the assembly bias. We demonstrate assembly bias alters the clustering in EAGLE by 20 per cent and Vrelax captures its effect to within 15 per cent. We trace small differences in the clustering to the failure of SHAM as typically implemented, i.e. the Mstar assigned to a subhalo does not depend on (i) its host halo mass, (ii) whether it is a central or a satellite. In EAGLE, we find that these assumptions are not completely satisfied
Seed dissemination by frugivorous birds from forest fragments to adjacent pastures on the western slope of Volcán Barva, Costa Rica
Logging, cattle raising, and agricultural activities have caused the destruction of most forested áreas in Costa Rica. In some middle and highlands the abrupt topography delayed the complete destruction of montane forest. Consequently, some fragments of almost pristine forest remain along streams that run in deep canyons. Frequently, these remnants serve as corridors between larger forested areas and as routes for movement of frugivorous birds. Eighteen bird species, e.g., Turdus plebejus, Elaenia frantzii and Ptilogonys caudatus are common dwellers of forest patches throughout the Pacific slope of the Volcán Barva. These species fly fre- quently from forest fragments to adjacent pastures. They defecated and regurgitated seeds of 28 plant species on stumps scattered on pasture areas. Isolated trees and specially the stumps are suitable microhabitats for germination of seeds and establishment of seedlings.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí
J-NEP: 60-band photometry and photometric redshifts for the James Webb Space Telescope North Ecliptic Pole Time-Domain Field
The J-PAS survey will observe ~1/3 of the northern sky with a set of 56
narrow-band filters using the dedicated 2.55 m JST telescope at the Javalambre
Astrophysical Observatory. Prior to the installation of the main camera, in
order to demonstrate the scientific potential of J-PAS, two small surveys were
performed with the single-CCD Pathfinder camera: miniJPAS (~1 deg2 along the
Extended Groth Strip), and J-NEP (~0.3 deg2 around the JWST North Ecliptic Pole
Time Domain Field), including all 56 J-PAS filters as well as u, g, r, and i.
J-NEP is ~0.5-1.0 magnitudes deeper than miniJPAS, providing photometry for
24,618 r-band detected sources and photometric redshifts (photo-z) for the
6,662 sources with r<23.
In this paper we describe the photometry and photo-z of J-NEP and demonstrate
a new method for the removal of systematic offsets in the photometry based on
the median colours of galaxies, dubbed "galaxy locus recalibration". This
method does not require spectroscopic observations except in a few reference
pointings and, unlike previous methods, is applicable to the whole J-PAS
survey.
We use a spectroscopic sample of 787 galaxies to test the photo-z performance
for J-NEP and in comparison to miniJPAS. We find that the deeper J-NEP
observations result in a factor ~1.5-2 decrease in sigma_NMAD (a robust
estimate of the standard deviation of the photo-z error) and the outlier rate
relative to miniJPAS for r>21.5 sources, but no improvement in brighter ones.
We find the same relation between sigma_NMAD and odds in J-NEP and miniJPAS,
suggesting sigma_NMAD can be predicted for any set of J-PAS sources from their
odds distribution alone, with no need for additional spectroscopy to calibrate
the relation. We explore the causes for photo-z outliers and find that
colour-space degeneracy at low S/N, photometry artifacts, source blending, and
exotic spectra are the most important factors.Comment: 16 pages, 25 figures, accepted for publication in Astronomy and
Astrophysic
The European Marine Observation and Data Network (EMODnet): Visions and roles of the gateway to marine data in Europe
Marine data are needed for many purposes: for acquiring a better scientific understanding of the marine environment, but also, increasingly, as marine knowledge for decision making as well as developing products and services supporting economic growth. Data must be of sufficient quality to meet the specific users' needs. It must also be accessible in a timely manner. And yet, despite being critical, this timely access to known-quality data proves challenging. Europe's marine data have traditionally been collected by a myriad of entities with the result that much of our data are scattered throughout unconnected databases and repositories. Even when data are available, they are often not compatible, making the sharing of the information and data aggregation particularly challenging. In this paper, we present how the European Marine Observation and Data network (EMODnet) has developed over the last decade to tackle these issues. Today, EMODnet is comprised of more than 150 organizations which gather marine data, metadata, and data products and make them more easily accessible for a wider range of users. EMODnet currently consists of seven sub-portals: bathymetry, geology, physics, chemistry, biology, seabed habitats, and human activities. In addition, Sea-basin Checkpoints have been established to assess the observation capacity in the North Sea, Mediterranean, Atlantic, Baltic, Artic, and Black Sea. The Checkpoints identify whether the observation infrastructure in Europe meets the needs of users by undertaking a number of challenges. To complement this, a Data Ingestion Service has been set up to tackle the problem of the wealth of marine data that remain unavailable, by reaching out to data holders, explaining the benefits of sharing their data and offering a support service to assist them in releasing their data and making them available through EMODnet. The EMODnet Central Portal (www.emodnet.eu) provides a single point of access to these services, which are free to access and use. The strategic vision of EMODnet in the next decade is also presented, together with key focal areas toward a more user-oriented service, including EMODnet for business, internationalization for global users, and stakeholder engagement to connect the diverse communities across the marine knowledge value chain
TOPz: Photometric redshifts for J-PAS
The importance of photometric galaxy redshift estimation is rapidly
increasing with the development of specialised powerful observational
facilities. We develop a new photometric redshift estimation workflow TOPz to
provide reliable and efficient redshift estimations for the upcoming
large-scale survey J-PAS which will observe 8500 deg2 of the northern sky
through 54 narrow-band filters. TOPz relies on template-based photo-z
estimation with some added J-PAS specific features and possibilities. We
present TOPz performance on data from the miniJPAS survey, a precursor to the
J-PAS survey with an identical filter system. First, we generated spectral
templates based on the miniJPAS sources using the synthetic galaxy spectrum
generation software CIGALE. Then we applied corrections to the input photometry
by minimising systematic offsets from the template flux in each filter. To
assess the accuracy of the redshift estimation, we used spectroscopic redshifts
from the DEEP2, DEEP3, and SDSS surveys, available for 1989 miniJPAS galaxies
with r < 22 magAB. We also tested how the choice and number of input templates,
photo-z priors, and photometric corrections affect the TOPz redshift accuracy.
The general performance of the combination of miniJPAS data and the TOPz
workflow fulfills the expectations for J-PAS redshift accuracy. Similarly to
previous estimates, we find that 38.6% of galaxies with r < 22 mag reach the
J-PAS redshift accuracy goal of dz/(1 + z) < 0.003. Limiting the number of
spectra in the template set improves the redshift accuracy up to 5%, especially
for fainter, noise-dominated sources. Further improvements will be possible
once the actual J-PAS data become available.Comment: 20 pages, 24 figure
The miniJPAS survey: Identification and characterization of the emission line galaxies down to in the AEGIS field
The Javalambre-Physics of the Accelerating Universe Astrophysical Survey
(J-PAS) is expected to map thousands of square degrees of the northern sky with
56 narrowband filters in the upcoming years. This will make J-PAS a very
competitive and unbiased emission line survey compared to spectroscopic or
narrowband surveys with fewer filters. The miniJPAS survey covered 1 deg,
and it used the same photometric system as J-PAS, but the observations were
carried out with the pathfinder J-PAS camera. In this work, we identify and
characterize the sample of emission line galaxies (ELGs) from miniJPAS with a
redshift lower than . Using a method based on artificial neural networks,
we detect the ELG population and measure the equivalent width and flux of the
, , [OIII], and [NII] emission lines. We explore the
ionization mechanism using the diagrams [OIII]/H versus [NII]/H
(BPT) and EW(H) versus [NII]/H (WHAN). We identify 1787 ELGs
(%) from the parent sample (2154 galaxies) in the AEGIS field. For the
galaxies with reliable EW values that can be placed in the WHAN diagram (2000
galaxies in total), we obtained that %, % , and
% are star-forming (SF), active galactic nucleus (Seyfert), and
quiescent galaxies, respectively. Based on the flux of we find that
the star formation main sequence is described as SFR and has an intrinsic scatter of . The cosmic evolution of the SFR density ()
is derived at three redshift bins: , , and
, which agrees with previous results that were based on
measurements of the emission line.Comment: 22 pages, 19 figure
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