210 research outputs found
Synchrotron Self-Absorption Process in GRBs and the Isotropic Energy - Peak Energy Fundamental Relation
The existence of strong correlation between the peak luminosity (and/or
bolometric energetics) of Gamma Ray Bursts (GRB) is one of the most intrigue
problem of GRB physics. This correlation is not yet understood. Here we
demonstrate that this correlation can be explained in framework of synchrotron
self-absorption (SSA) mechanism of GRB prompt emission. We estimate the
magnetic field strength of the central engine at the level , where is the Lorentz factor of fireball.Comment: 5 page
Impact of Baryonic Physics on Intrinsic Alignments
We explore the effects of specific assumptions in the subgrid models of star
formation and stellar and AGN feedback on intrinsic alignments of galaxies in
cosmological simulations of "MassiveBlack-II" family. Using smaller volume
simulations, we explored the parameter space of the subgrid star formation and
feedback model and found remarkable robustness of the observable statistical
measures to the details of subgrid physics. The one observational probe most
sensitive to modeling details is the distribution of misalignment angles. We
hypothesize that the amount of angular momentum carried away by the galactic
wind is the primary physical quantity that controls the orientation of the
stellar distribution. Our results are also consistent with a similar study by
the EAGLE simulation team.Comment: 7 pages, 6 figures, submitted to Ap
Probing the universe with the Lyman- forest; 3, The mean opacity of the IGM
I apply the well controlled Hydro-PM approximation of Gnedin & Hui to study the consistency between the column density distribution of the Lyman-alpha forest and the mean opacity of the IGM for 25 different flat cosmological scenarios, including variants of the standard CDM, tilted CDM, CDM with a cosmological constant, and CHDM models. I show that the observational data of Press, Rybicki, and Schneider are not compatible with the hypothesis that the Lyman-alpha forest arises from fluctuations in the low density IGM, whereas the data of Zuo and Lu and Lu et al. are in a full agreement with the level of the ionizing intensity required to reproduce the observed column density distribution of the Lyman-alpha forest. Thus, either the data of Press, Rybicki, and Schneider are contaminated, or the hypothesis that the Lyman-alpha forest arises from density fluctuations in the IGM is invalid
Probing the universe with the Lyman- forest; 2, The column density distribution
I apply the well controlled Hydro-PM approximation of Gnedin & Hui to model the column density distribution of the Lyman-alpha forest for 25 different flat cosmological scenarios, including variants of the standard CDM, tilted CDM, CDM with a cosmological constant, and CHDM models. I show that within the accuracy of the HPM approximation the slope of the column density distribution reflects the degree of nonlinearity of the cosmic gas distribution and is a function of the rms linear density fluctuation at the characteristic filtering scale only. The amplitude of the column density distribution, expressed as the value for the ionizing intensity, is derived as a function of the cosmological parameters (to about 30% accuracy). The observational data are currently consistent with the value for the ionizing intensity both being constant in the redshift interval z~2-4 and peaking by about 30% at z~3. The majority (if not all) of flat cosmological models have difficulty in simultaneously achieving sufficiently low power spectrum amplitude at the cluster scale to fit the observed cluster abundances, and sufficiently high amplitude at the Lyman-alpha forest scale to reproduce the observed shallow column density distribution. While the discrepancy is not statistically significant at the moment, if confirmed in the future, it may indicate that there exist another population of objects contributing to the unsaturated Lyman-alpha absorption along lines of sight towards distant quasars
Astrophysical Polarimetric Signature Against TeV Fundamental Planck Scale
I present the analysis of data of astrophysical polarimetric observations
that gives the signature of the fundamental extra dimension Planck scale
magnitude essentially higher than . Magnetic conversion of photons into
the fundamental particles (scalars, gravitons) is the probable mechanism that
can produce noticeable amount of polarization of optical radiation of
astrophysical objects, especially, of distant extragalactic sources. The
results of magnetic conversion process of optical light of extragalactic
sources are presented for a number of situations including: (a) intergalactic
magnetic field, (b) galaxy cluster magnetic field, (c) magnetic conversion in
the typical galaxy magnetic field, (d) magnetic conversion of CMB radiation
Constraints on Spin of a Supermassive Black Hole in Quasars with Big Blue Bump
We determined the spin value of supermassive black hole (SMBH) in active
galactic nuclei (AGN) with investigated ultraviolet-to-optical spectral energy
distribution, presented in the sample of Shang et al. (2005). The estimates of
the spin values have been produced at the base of the standard geometrically
thin accretion disk model and with using the results of the polarimetric
observations. The polarimetric observations are very important for determining
the inclination angle of AGN disk. We presented the results of our
determinations of the radiation efficiency of the accretion flow and values of
the spins of SMBHs, that derives the coefficient of radiation efficiency. The
majority of SMBHs of AGNs from Shang et al. (2005) sample are to be the Kerr
black holes with the high spin value.Comment: 5 pages, 1 figur
Magnetic Fields of Black Holes and the Variability Plane
We estimated the magnetic field strength at the horizon radius of black
holes, that is derived by the magnetic coupling process and depended on the
black hole mass and the accretion rate . Our estimation is
based on the use of the fundamental variability plane for stellar mass black
holes, AGNs and QSOs. The typical values of magnetic field strength on the
black hole horizon are appeared at the level of G for stellar
mass black holes and G for the supermassive black holes. We
have obtained the relation between the intrinsic
polarization of the accretion disk radiation and the characteristic frequency
of the black hole X-ray variability.Comment: 4 page
On solar neutrino fluxes in radiochemical experiments
We analyze fluctuations of the solar neutrino flux using data from the
Homestake, GALLEX, GNO, SAGE and Super Kamiokande experiments. Spectral
analysis and direct quantitative estimations show that the most stable
variation of the solar neutrino flux is a quasi-five-year periodicity. The
revised values of the mean solar neutrino flux are presented in Table 4. They
were used to estimate the observed pp-flux of the solar electron neutrinos near
the Earth. We consider two alternative explanations for the origin of a
variable component of the solar neutrino deficit.Comment: 18 pages, 4 figures, 5 tables, 27 references. The paper is extended
version of the report presented on 9th International Pulkovo Conference on
Solar Physics, Saint-Petersburg, Russia, July 4-9, 200
Intrinsic Origin Of Extreme-Scale Rotation Of Quasar Polarization Vectors
Extreme-scale alignment of quasar optical polarization vectors at
cosmological scales () is also characterized by the rotation of mean
position angle with per 1 Gpc. For
observing interval of the total rotation angle acquires the value . We suggest the possible explanation of the half of this rotation
as a consequence of physical transformation of initially vertical magnetic
field , directed along the normal to the surface of
accretion disk, into the horizontal (perpendicular to ) one. We found
asymptotical analytical expressions for axially averaged polarization degree
and mean position angle for various types of magnetized accretion
disks. We found also that during the evolution can be realized the case
where position angle rotates from
to zero. This rotation may occur during fairly great cosmological time
(corresponding to ). The part of rotation can be explained by a mechanism of alignment of
polarization vectors, say distribution of the part of quasars as a spiral in
the cosmic space with slow variation of rotation axis of corresponding
accretion disks. Both mechanisms are mutually related one with another.Comment: 7 page
The Black Hole Mass and Magnetic Field Correlation in AGN: Testing by Optical Polarimetry
We consider the integral light polarization from optically thick accretion
disks. Basic mechanism is the multiple light scattering on free electrons
(Milne's problem) in magnetized atmosphere. The Faraday rotation of the
polarization plane changes both the value of integral polarization degree
and the position angle . Besides, the characteristic spectra of these
values appear. We are testing the known relation between magnetic field of
black hole at the horizon and its mass , and the usual
power-law distribution inside the accretion disk. The formulae for
and depend on a number of parameters describing the particular
dependence of magnetic field in accretion disk (the index of power-law
distribution, the spin of the black hole, etc.). Comparison of our theoretical
values of and with observed polarization can help us to choice more
realistic values of parameters if the accretion disk mechanism gives the main
contribution to the observed integral polarization. The main content is
connected with estimation of validity of the relation between and
. We found for the AGN NGC 4258 that such procedure does not confirm
the mentioned correlation between magnetic field and mass of black hole.Comment: 7 page
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