98 research outputs found
Gravitational collapse of Type II fluid in higher dimensional space-times
We find the general solution of the Einstein equation for spherically
symmetric collapse of Type II fluid (null strange quark fluid) in higher
dimensions. It turns out that the nakedness and curvature strength of the shell
focusing singularities carry over to higher dimensions. However, there is
shrinkage of the initial data space for a naked singularity of the Vaidya
collapse due to the presence of strange quark matter.Comment: RevTex4 style, 4 pages; Accepted in Phys. Rev.
The first 62 AGN observed with SDSS-IV MaNGA - IV: gas excitation and star-formation rate distributions
We present maps of the ionized gas flux distributions, excitation,
star-formation rate SFR, surface mass density , and obtain total
values of SFR and ionized gas masses {\it M} for 62 Active Galactic Nuclei
(AGN) observed with SDSS-IV MaNGA and compare them with those of a control
sample of 112 non-active galaxies. The most luminous AGN -- with
L(\rm{[OIII]}\lambda 5007) \ge 3.8\times 10^{40}\,\mbox{erg}\,\mbox{s}^{-1},
and those hosted by earlier-type galaxies are dominated by Seyfert excitation
within 0.2 effective radius from the nucleus, surrounded by LINER
excitation or transition regions, while the less luminous and hosted by
later-type galaxies show equally frequent LINER and Seyfert excitation within
. The extent of the region ionized by the AGN follows the
relation -- as in the case of the Broad-Line
Region. The SFR distribution over the region ionized by hot stars is similar
for AGN and controls, while the integrated SFR -- in the range
\,M\,yr is also similar for the late-type
sub-sample, but higher in the AGN for 75\% of the early-type sub-sample. We
thus conclude that there is no signature of AGN quenching star formation in the
body of the galaxy in our sample. We also find that 66\% of the AGN have higher
ionized gas masses than the controls -- in the range
10\,M -- while 75\% of the AGN have higher
within than the control galaxies
Dimensionally continued Oppenheimer-Snyder gravitational collapse. I - solutions in even dimensions
The extension of the general relativity theory to higher dimensions, so that
the field equations for the metric remain of second order, is done through the
Lovelock action. This action can also be interpreted as the dimensionally
continued Euler characteristics of lower dimensions. The theory has many
constant coefficients apparently without any physical meaning. However, it is
possible, in a natural way, to reduce to two (the cosmological and Newton's
constant) these several arbitrary coefficients, yielding a restricted Lovelock
gravity. In this process one separates theories in even dimensions from
theories in odd dimensions. These theories have static black hole solutions. In
general relativity, black holes appear as the final state of gravitational
collapse. In this work, gravitational collapse of a regular dust fluid in even
dimensional restricted Lovelock gravity is studied. It is found that black
holes emerge as the final state for these regular initial conditions.Comment: Late
The first 62 AGN observed with SDSS-IV MaNGA -- III: stellar and gas kinematics
We investigate the effects of Active Galactic Nuclei (AGN) on the gas
kinematics of their host galaxies, using MaNGA data for a sample of 62 AGN
hosts and 109 control galaxies (inactive galaxies). We compare orientation of
the line of nodes (kinematic Position Angle - PA) measured from the gas and
stellar velocity fields for the two samples. We found that AGN hosts and
control galaxies display similar kinematic PA offsets between gas and stars.
However, we note that AGN have larger fractional velocity dispersion
differences between gas and stars [] when compared to their controls, as
obtained from the velocity dispersion values of the central (nuclear) pixel
(2.5" diameter). The AGN have a median value of of
, while the the median value for the control
galaxies is . 75% of the AGN show
, while 75% of the normal galaxies show , thus we suggest that the parameter can be
used as an indicative of AGN activity. We find a correlation between the
[OIII]5007 luminosity and for our sample. Our main
conclusion is that the AGN already observed with MaNGA are not powerful enough
to produce important outflows at galactic scales, but at 1-2 kpc scales, AGN
feedback signatures are always present on their host galaxies.Comment: 19 pages, 8 figures, published in MNRA
Naked singularities in Tolman-Bondi-de Sitter collapse
We study the formation of central naked singularities in spherical dust
collapse with a cosmological constant. We find that the central curvature
singularity is locally naked, Tipler strong, and generic, in the sense that it
forms from a non-zero-measure set of regular initial data. We also find that
the Weyl and Ricci curvature scalars diverge at the singularity, with the
former dominating over the latter, thereby signaling the non-local origin of
the singularity.Comment: 8 pages, RevTeX, 1 eps figure; accepted for publication in Phys. Rev.
Dual embedding of the Lorentz-violating electrodinamics and Batalin-Vilkovisky quantization
Modifications of the electromagnetic Maxwell Lagrangian in four dimensions
have been considered by some authors. One may include an explicit massive term
(Proca) and a topological but not Lorentz-invariant term within certain
observational limits.
We find the dual-corresponding gauge invariant version of this theory by
using the recently suggested gauge embedding method. We enforce this
dualisation procedure by showing that, in many cases, this is actually a
constructive method to find a sort of parent action, which manifestly
establishes duality. We also use the gauge invariant version of this theory to
formulate a Batalin-Vilkovisky quantization and present a detailed discussion
on the excitation spectrum.Comment: 8 page
Identificação do estado de portador sadio de Babesia bigemina em bovinos através da técnica de PCR
Neste trabalho foi comparada a técnica de reação em cadeia da polimerase (PC R) com o procedimento de subinoculação para a identificação de portadores sadios
Ionised gas kinematics in MaNGA AGN: Extents of the narrow-line and kinematically disturbed regions
Context. Feedback from active galactic nuclei (AGNs) in general seems to play an important role in the evolution of galaxies, although the impact of AGN winds on their host galaxies is still unknown in the absence of a detailed analysis. Aims. We aim to analyse the kinematics of a sample of 170 AGN host galaxies as compared to those of a matched control sample of non-active galaxies from the MaNGA survey in order to characterise and estimate the extents of the narrow-line region (NLR) and of the kinematically disturbed region (KDR) by the AGN. Methods. We defined the observed NLR radius (rNLR,âo) as the farthest distance from the nucleus within which both [OâŻIII]/HÎČ and [NâŻII]/Hα ratios fall in the AGN region of the BPT diagram, and the Hα equivalent width was required to be larger than 3.0 Ă
. The extent of the KDR (rKDR,âo) is defined as the distance from the nucleus within which the AGN host galaxies show a more disturbed gas kinematics than the control galaxies. Results. The AGN [OâŻIII]λ5007 luminosity ranges from 1039 to 1041 erg sâ1, and the kinematics derived from the [OâŻIII] line profiles reveal that, on average, the most luminous AGNs (L[OâŻIII] > 3.8â
Ăâ
1040 erg sâ1) possess higher residual differences between the gaseous and stellar velocities and velocitie dispersions than their control galaxies in all the radial bins. Spatially resolved NLRs and KDRs were found in 55 and 46 AGN host galaxies, with corrected radii 0.2â<ârKDR,âcâ<â2.3 kpc and 0.4â<ârNLR,âcâ<â10.1 kpc and a relation between the two given by log rKDR,âcâ=â(0.53â
屉
0.12)âlog rNLR,âcâ
+â
(1.07â
屉
0.22), respectively. On average, the extension of the KDR corresponds to about 30% of that of the NLR. Assuming that the KDR is due to an AGN outflow, we have estimated ionised gas mass outflow rates that range between 10â5 and âŒ1 Mâ yrâ1, and kinetic powers that range from 1034 to 1040 erg sâ1. Conclusions. Comparing the power of the AGN ionised outflows with the AGN luminosities, they are always below the 0.05 LAGN model threshold for having an important feedback effect on their respective host galaxies. The mass outflow rates (and power) of our AGN sample correlate with their luminosities, populating the lowest AGN luminosity range of the correlations previously found for more powerful sources. © ESO 2022.This study was funded in part by the Coordenação de Aperfeiçoamento de Pessoal de NĂvel Superior â Brasil (CAPES) â Finance Code 001, Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq) and Fundação de Amparo Ă pesquisa do Estado do RS (FAPERGS). ADM acknowledges financial support from the Spanish MCIU grant PID2019-106027GB-C41 and from the State Agency for Research of the Spanish MCIU through the âCenter of Excellence Severo Ochoaâ award for the Instituto de AstrofĂsica de AndalucĂa (SEV-2017-0709). ADM also acknowledges the support of the INPhINIT fellowship form âla Caixaâ Foundation (ID 100010434), under the fellowship code LCF/BQ/DI19/11730018. SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofisica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut fĂŒr Astrophysik Potsdam (AIP), Max-Planck-Institut fĂŒr Astronomie (MPIA Heidelberg), Max-Planck-Institut fĂŒr Astrophysik (MPA Garching), Max-Planck-Institut fĂŒr Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, ObservatĂłrio Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional AutĂłnoma de MĂ©xico, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.Peer reviewe
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