269 research outputs found
Statistical multifrequency study of narrow-line Seyfert 1 galaxies
High-energy {\gamma}-rays, which are produced by powerful relativistic jets,
are usually associated with blazars and radio galaxies. In the current active
galactic nuclei (AGN) paradigm, such jets are almost exclusively launched from
massive elliptical galaxies. Recently, however, Fermi/LAT detected
{\gamma}-rays from a few narrow-line Seyfert 1 galaxies and thus confirmed the
presence of relativistic jets in them. Since NLS1 galaxies are assumed to be
young evolving AGN, they offer a unique opportunity to study the production of
relativistic jets in late-type galaxies. Our aim is to estimate by which
processes the emission of various kinds is produced in NLS1 galaxies and to
study how emission properties are connected to other intrinsic AGN properties.
We have compiled the so far largest multiwavelength database of NLS1 sources.
This allowed us to explore correlations between different wavebands and source
properties using, for example, Pearson and Spearman correlations and principal
component analysis. We did this separately for radio-loud and radio-quiet
sources. Multiwavelength correlations suggest that radio-loud sources host
relativistic jets that are the predominant sources of radio, optical, and X-ray
emission. The origin of infrared emission remains unclear. Radio-quiet sources
do not host a jet, or the jet is very weak. In them, radio and infrared
emission is more likely generated via star formation processes, and the optical
and X-ray emission originate in the inner parts of the AGN. We also find that
the black hole mass correlates significantly with radio loudness, which
suggests that NLS1 galaxies with more massive black holes are more likely to be
able to launch powerful relativistic jets.Comment: 29 pages, 7 figures, accepted for publication in Astronomy &
Astrophysic
Starbursts and black hole masses in X-shaped radio galaxies: Signatures of a merger event?
We present new spectroscopic identifications of 12 X-shaped radio galaxies
and use the spectral data to derive starburst histories and masses of the
nuclear supermassive black holes in these galaxies. The observations were done
with the 2.1-m telescope of the Observatorio Astron\'omico Nacional at San
Pedro M\'artir, M\'exico. The new spectroscopic results extend the sample of
X-shaped radio galaxies studied with optical spectroscopy. We show that the
combined sample of the X-shaped radio galaxies has statistically higher
black-hole masses and older episodes of star formation than a control sample of
canonical double-lobed radio sources with similar redshifts and luminosities.
The data reveal enhanced star-formation activity in the X-shaped sample on the
timescales expected in galactic mergers. We discuss the results obtained in the
framework of the merger scenario.Comment: 9 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
Cluster Galaxy Morphologies: The Relationship among Structural Parameters, Activity and the Environment
We use an approach to estimate galaxy morphologies based on an ellipticity
(e) vs. Bulge-to-Total ratio (B/T) plane. We have calibrated this plane by
comparing with Dressler's classifications. With the aid of our calibration, we
have classified 635 galaxies in 18 Abell clusters (0.02 < z < 0.08). Our
approach allowed us to recover the Kormendy's relation. We found that
ellipticals and Spirals are slightly brighter than S0 in R band. As S0 bulges
are brighter than spirals bulges, we believe that ram pressure is not the main
mechanism to generate S0s. In our sample, cluster radio galaxies morphologies
cover the range S0-E-cD and their bulges have absolutes magnitudes distributed
within -21 mag < M < -24.5 mag. If we believe Ferrarese & Merrit's relation,
these radio sources have 10^8-10^9 M black hole mass.Comment: Originally published in the proceedings of the conference "The
Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters", AIP
Conference Proceedings, Volume 1201 edited by Sebastian Heinz and Eric
Wilcots. This version contains slight modification
The XMM spectral catalog of SDSS optically selected Seyfert 2 galaxies
We present an X-ray spectroscopic study of optically selected (SDSS) Seyfert
2 (Sy2) galaxies. The goal is to study the obscuration of Sy2 galaxies beyond
the local universe, using good quality X-ray spectra in combination with high
S/N optical spectra for their robust classification. We analyzed all available
XMM-Newton archival observations of narrow emission line galaxies that meet the
above criteria in the redshift range 0.05<z<0.35. We initially selected narrow
line AGN using the SDSS optical spectra and the BPT classification diagram. We
further modeled and removed the stellar continuum, and we analyzed the residual
emission line spectrum to exclude any possible intermediate-type Seyferts. Our
final catalog comprises 31 Sy2 galaxies with median redshift z~0.1. X-ray
spectroscopy is performed using the available X-ray spectra from the 3XMM and
the XMMFITCAT catalogs. Implementing various indicators of obscuration, we find
seven (~23%) Compton-thick AGN. The X-ray spectroscopic Compton-thick
classification agrees with other commonly used diagnostics, such as the X-ray
to mid-IR luminosity ratio and the X-ray to [OIII] luminosity ratio. Most
importantly, we find four (~13%) unobscured Sy2 galaxies, at odds with the
simplest unification model. Their accretion rates are significantly lower than
the rest of our Sy2 sample, in agreement with previous studies that predict the
absence of the broad line region below a certain Eddington ratio threshold.Comment: 12 pages, 6 figures, accepted for publication in A&
Depresión según el CDI (Children's Depression Inventory) en niños y adolescentes en el H.G.R. 36/I.M.S.S. portadores de enfermedad renal crónica
"La depresión como trastorno del estado de ánimo, según el informe de la Organización Mundial de la Salud, aparece como la principal causa de discapacidad y la cuarta de las 10 causas principales, de morbilidad en el ámbito mundial. La prevalencia exacta, se desconoce, ya que varía según los estudios realizados. Se estima que la depresión entre pacientes con enfermedad médica no psiquiátrica, oscila entre 15-61%. Amy y cols. 2013, en una muestra de 44 niños de 9 a 18 años de edad, portadores de enfermedad renal crónica, reporto una prevalencia de depresión en un 30%.
Targeting the hemangioblast with a novel cell type-specific enhancer
<p>Abstract</p> <p>Background</p> <p>Hemangioblasts are known as the common precursors for primitive hematopoietic and endothelial lineages. Their existence has been supported mainly by the observation that both cell types develop in close proximity and by in vitro differentiation and genetic studies. However, more compelling evidence will arise from tracking their cell fates using a lineage-specific marker.</p> <p>Results</p> <p>We report the identification of a hemangioblast-specific enhancer (Hb) located in the <it>cis</it>-regulatory region of chick <it>Cerberus </it>gene (<it>cCer</it>) that is able to direct the expression of enhanced green fluorescent protein (eGFP) to the precursors of yolk sac blood and endothelial cells in electroporated chick embryos. Moreover, we present the Hb-eGFP reporter as a powerful live imaging tool for visualizing hemangioblast cell fate and blood island morphogenesis.</p> <p>Conclusions</p> <p>We hereby introduce the Hb enhancer as a valuable resource for genetically targeting the hemangioblast population as well as for studying the dynamics of vascular and blood cell development.</p
VLBI and Single Dish Monitoring of 3C84 in the Period of 2009-2011
The radio galaxy 3C 84 is a representative of gamma-ray-bright misaligned
active galactic nuclei (AGNs) and one of the best laboratories to study the
radio properties of the sub-pc jet in connection with the gamma-ray emission.
In order to identify possible radio counterparts of the gamma-ray emissions in
3C 84, we study the change in structure within the central 1 pc and the light
curve of sub-pc-size components C1, C2, and C3. We search for any correlation
between changes in the radio components and the gamma-ray flares by making use
of VLBI and single dish data. Throughout the radio monitoring spanning over two
GeV gamma-ray flares detected by the {\it Fermi}-LAT and the MAGIC Cherenkov
Telescope in the periods of 2009 April to May and 2010 June to August, total
flux density in radio band increases on average. This flux increase mostly
originates in C3. Although the gamma-ray flares span on the timescale of days
to weeks, no clear correlation with the radio light curve on this timescale is
found. Any new prominent components and change in morphology associated with
the gamma-ray flares are not found on the VLBI images.Comment: 6 pages, 3 figures, accepted for publication in MNRAS lette
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