50 research outputs found
The estimation of black-hole masses in distant radio galaxies
We have estimated the masses of the central supermassive black holes of 2442
radio galaxies froma catalog compiled using data from the NED, SDSS, and CATS
databases. Mass estimates based on optical photometry and radio data are
compared. Relationships between the mass of the central black hole
and the redshift are constructed for both wavelength ranges. The
distribution of the galaxies in these diagrams and systematic effects
influencing estimation of the black-hole parameters are discussed.
Upperenvelope cubic regression fits are obtained using the maximum estimates of
the black-hole masses. The optical and radio upper envelopes show similar
behavior, and have very similar peaks in position, , and
amplitude, = 9.4. This is consistent with a model in which the
growth of the supermassive black holes is self-regulating, with this redshift
corresponding to the epoch when the accretion-flow phase begins to end and the
nuclear activity falls off.Comment: 8 pages, 6 figure
GRB Sky Distribution Puzzles
We analyze the randomness of the sky distribution of cosmic gamma-ray bursts.
These events are associated with massive galaxies, spiral or elliptical, and
therefore their positions should trace the large-scale structure, which, in
turn, could show up in the sky distribution of fluctuations of the cosmic
microwave background (CMB). We test this hypothesis by mosaic correlation
mapping of the distributions of CMB peaks and burst positions, find the
distribution of these two signals to be correlated, and interpret this
correlation as a possible systematic effect.Comment: 12 pages, 16 figures, 1 tabl
Statistics of WMAP ILC map temperature fluctuations towards distant radio galaxies
For 2442 galaxies of the catalog, compiled based on the NED, SDSS, and CATS
survey data with redshifts z, > 0.3 we conducted an analysis of the amplitude
of temperature fluctuations in the cosmic microwave background (CMB) in the
points, corresponding to the direction to these objects. To this end, we used
the ILC map from the WMAP mission seven-year data release. We have estimated
the dipole component of the background and tested the hypothesis of Kashlinsky
on the existence of a "dark bulk flow", determined for the estimated dipole
component of the CMB WMAP by the value of the CMB anisotropy in the direction
to the clusters of galaxies. We show that the amplitude of this dipole T max =
0.012mK is located within the {\sigma} interval, estimated by Monte Carlo
simulations for the Gaussian fluctuations of the CMB signal in the {\Lambda}CDM
model. The low amplitude of the dipole indicates that it is impossible to
confirm this hypothesis from the WMAP data. In addition, we studied the
statistics of the fluctuation amplitude of the microwave signal in the
direction to radio galaxies. A weakening of the absolute value of the mean
signal in the corresponding fields was discovered.Comment: 7 pages,4 figures,1 tabl
On the Spectral Index of Distant Radio Galaxies
The problems of using the spectral index of radio galaxies in various tests,
in particular, in selecting distant radio sources are considered. The history
of the question of choosing a criterion of searching for distant radio galaxies
based on the spectral index is presented. For a new catalog of 2442 radio
galaxies constructed from NED, SDSS, and CATS data, an analytical form of the
sp ectral index.redshift relation has been determined for the first time. The
spectral index.angular size and spectral index.flux density diagrams have also
been constructed. Peculiarities of the distribution of sources on these
diagrams are discussed.Comment: 7 pages,5 figure
Radio properties of high-redshift galaxies at
Study of high-redshift radio galaxies (HzRGs) can shed light on the active
galactic nuclei (AGNs) evolution in massive elliptical galaxies. The vast
majority of observed high-redshift AGNs are quasars, and there are very few
radio galaxies at redshifts . We present the radio properties of 173
sources optically identified with radio galaxies at with flux
densities mJy. Literature data were collected for
compilation of broadband radio spectra, estimation of radio variability, radio
luminosity, and radio loudness. Almost 60% of the galaxies have steep or
ultra-steep radio spectra; 22% have flat, inverted, upturn, and complex
spectral shapes, and 18% have peaked spectra (PS). The majority of the PS
sources in the sample (20/31) are megahertz-peaked spectrum sources candidates,
i.e. possibly very young and compact radio galaxies. The median values of the
variability indices at 11 and 5 GHz are and ,
which generally indicates a weak or moderate character of the long-term
variability of the studied galaxies. The typical radio luminosity and radio
loudness are - erg*s and -
respectively. We have found less prominent features of the bright compact radio
cores for our sample compared to high-redshift quasars at . The variety
of the obtained radio properties shows the different conditions for the
formation of radio emission sources in galaxies
Radio Spectra of Giant Radio Galaxies from RATAN-600 Data
Measurements of the flux densities of the extended components of seven giant
radio galaxies obtained using the RATAN-600 radio telescope at wavelengths of
6.25 and 13 cm ar e presented. The spectra of components of these radio
galaxies are constructed using these new RA TAN-600 data together with data
from the WENSS, NVSS, and GB6 surveys. The spectral indices in the stu died
frequency range are calculated, and the need for detailed estimates of the
integrated contributi on of such objects to the background emission is
demonstrated.Comment: 7 pages, 2 figures, 5 table
V1327 aquilae: A new RR lyrae variable with an extremely high radial velocity
We have carried out photometry and spectroscopy of the star V1327 Aql (R = 16 m ) as part of our program of observations of poorly studied cataclysmic variables using the 1.5-m optical Russian-Turkish telescope (RTT-150, Turkey) and the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. After analyzing our photometry, we have re-classified the variable as an RR Lyrae star. Our BV R photometry during 10 nights reveals brightness variations with the period 12 h49 m, with the B, V, and R amplitudes being 1.36 m , 1.13 m , and 1.11 m , respectively. We derived the first estimates of the star's atmospheric parameters from our moderate-resolution spectra: T eff = 6280 K, log g = 3.3, [M/H] = -1.05. The extremely high radial velocity of the star's motion (V R = -470 km/s) and the star's large distances to the Galactic center (13.1 kpc) and disk (4.2 kpc) testify to a probable extragalactic origin of this object. © 2008 Pleiades Publishing, Ltd
Dominant Multipoles in WMAP5 Mosaic Data Correlation Maps
The method of correlation mapping on the full sphere is used to study the
properties of the ILC map, as well as the dust and synchrotron background
components. An anomalous correlation of the components with the ILC map in the
main plane and in the poles of the ecliptic and equatorial coordinate systems
was discovered. Apart from the bias, a dominant quadrupole contribution in the
power spectrum of the mosaic correlation maps was found in the pixel
correlation histogram. Various causes of the anomalous signal are discussed.Comment: 10 pages,11 figure
V1327 aquilae: A new RR lyrae variable with an extremely high radial velocity
We have carried out photometry and spectroscopy of the star V1327 Aql (R = 16 m ) as part of our program of observations of poorly studied cataclysmic variables using the 1.5-m optical Russian-Turkish telescope (RTT-150, Turkey) and the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. After analyzing our photometry, we have re-classified the variable as an RR Lyrae star. Our BV R photometry during 10 nights reveals brightness variations with the period 12 h49 m, with the B, V, and R amplitudes being 1.36 m , 1.13 m , and 1.11 m , respectively. We derived the first estimates of the star's atmospheric parameters from our moderate-resolution spectra: T eff = 6280 K, log g = 3.3, [M/H] = -1.05. The extremely high radial velocity of the star's motion (V R = -470 km/s) and the star's large distances to the Galactic center (13.1 kpc) and disk (4.2 kpc) testify to a probable extragalactic origin of this object. © 2008 Pleiades Publishing, Ltd
Catalog of Radio Galaxies with z>0.3. I:Construction of the Sample
The procedure of the construction of a sample of distant () radio
galaxies using NED, SDSS, and CATS databases for further application in
statistical tests is described. The sample is assumed to be cleaned from
objects with quasar properties. Primary statistical analysis of the list is
performed and the regression dependence of the spectral index on redshift is
found.Comment: 9 pages, 6 figures, 2 table