251 research outputs found
Magnetic Fields of Nearby Active Galactic Nuclei and Correlation of the Highest-Energy Cosmic Rays with their Positions
The correlation between the pointing direction of ultra high energy cosmic
rays and AGN observed by the Pierre Auger Collaboration is explained in the
framework of acceleration process in AGN. This acceleration process is produced
by a rotating accretion disk around a black hole that is frozen-in magnetic
field. In a result the accretion disk is acting as a induction accelerator of
cosmic rays. We estimate the resulting magnetic field in the framework of the
magnetic coupling process. The results of our calculations allow to make the
conclusion that the Flat Spectrum Radio Quasars appear the effective cosmic
accelerators. We estimate also the attenuation of highest-energy cosmic rays in
a result of their interaction with ambient radiation field.Comment: 5 page
Photon-Axion-Like Particle Coupling Constant and Cosmological Observations
We estimated the photon-pseudoscalar particle mixing constant from the effect
of cosmological alignment and cosmological rotation of polarization plane of
distant QSOs. This effect is explained in terms of birefringent phenomenon due
to photon-pseudoscalar (axion-like) particle mixing in a cosmic magnetic field.
On the contrary, one can estimate the strength of the cosmic magnetic field
using the constraints on the photon-axion-like particle coupling constant from
the CAST experiment and from SNe Ia dimming effect. In a result, the lower
limit on the intergalactic () magnetic field appears at the
level of about G.Comment: 8 page
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
Magnetic fields of active galaxy nuclei and cosmological models
We present the review of various methods of detection of magnetic field
strengths in the nearest regions of the active galaxy nuclei (AGN) which are
the high energetic machines. Original spectropolarimetric method developed in
the Pulkovo Observatory allows us to determine the magnitude and geometry of
the magnetic field in the region of the optical and more hard electromagnetic
radiation. The results of theoretical calculations are compared to the results
of spectropolarimetric observations of AGN. We used the method of determining
magnetic fields through the spectrum synchrotron radiation in the region of
synchrotron self-absorption. As the magnitude of magnetic field of the
extragalactic source depends very strongly on the angular size of extragalactic
source and therefore on the photometric distance the calculated magnetic field
magnitudes depends very strongly on the definite cosmological model. This
result allows us to present the new method for determination of the most
important cosmological parameters including dark matter and dark energy
parameters.Comment: 8 pages, 7 figure
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
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