269 research outputs found
Broad spectral line and continuum variabilities in QSO spectra induced by microlensing of diffusive massive substructure
We investigate the variability of the continuum and broad lines in QSO
spectra (particularly in the H line and continuum at 5100 \AA
) caused by microlensing of a diffuse massive structure (like an open star
cluster). We modeled the continuum and line emitting region and simulate a
lensing event by a star cluster located in an intervening galaxy. Such a type
of microlensing event can have a significant influence on magnification and
centroid shift of the broad lines and continuum source. We explore
relationships between the continuum and broad line flux variability during the
microlensing event.Comment: 19 pages, 11 figure
Spectro-photometric variability of quasars caused by lensing of diffuse massive substructure: Consequences on flux anomaly and precise astrometric measurements
We investigate the spectro-photometric variability of quasars due to lensing
of small mass substructure (from several tens to several hundreds solar
masses). The aim of this paper is to explore the milli/microlensing influence
on the flux anomaly observed between images of a lensed quasar in different
spectral bands and possible influence of small mass structure lensing of
non-macrolensed quasars.We find that spectro-photometric variability may be
also caused by lensing of small mass diffuse structure and can produce the flux
anomaly which is sometimes seen in different images of a lensed quasar.
Additionally, we found that the lensing by small mass diffuse structure may
produce significant changes in photo-center position of a quasar, and sometimes
can split or deviate images of one source that can be detected as separate from
the scale from 0.1 to several milliarcseconds. This can be measured ith
Gaialike space astrometric missions. We point out a special case where a low
redshifted deflector zd = 0.01 is lensing a high redshifted source, for which
the variability in the flux and photocenter (several milliarcseconds) may be
detected on a relatively short time scale.Comment: 10-pages, 10-figures, 3-table
Stark broadening data for spectral lines of rare-earth elements: Nb III
The electron-impact widths for 15 doubly charged Nb ion lines have been
theoretically determined by using the modified semiempirical method. Using the
obtained results, we considered the influence of the electron-impact mechanism
on line shapes in spectra of chemically peculiar stars and white dwarfs.Comment: 10 pages, 2 figures, 1 table, accepted in Advances in Space Researc
Gravitational microlensing of AGN dusty tori
We investigated the gravitational microlensing of active galactic nucleus
dusty tori in the case of lensed quasars in the infrared domain. The dusty
torus is modeled as a clumpy two-phase medium. To obtain spectral energy
distributions and images of tori at different wavelengths, we used the 3D Monte
Carlo radiative transfer code SKIRT. A ray-shooting technique has been used to
calculate microlensing magnification maps. We simulated microlensing by the
stars in the lens galaxy for different configurations of the lensed system and
different values of the torus parameters, in order to estimate (a) amplitudes
and timescales of high magnification events, and (b) the influence of
geometrical and physical properties of dusty tori on light curves in the
infrared domain. We found that, despite their large size, dusty tori could be
significantly affected by microlensing in some cases, especially in the
near-infrared domain (rest-frame). The very long time-scales of such events, in
the range from several decades to hundreds of years, are limiting the practical
use of this method to study the properties of dusty tori. However, our results
indicate that, when studying flux ratios between the images in different
wavebands of lensed quasars, one should not disregard the possibility that the
near and mid-infrared flux ratios could be under the influence of microlensing.Comment: 10 pages, 6 figures, 1 table, MNRAS accepted. V3: corrected values in
Table
Black Hole Mass Estimation in Type 1 AGN: H vs. Mg II lines and the role of Balmer continuum
Here we investigate the H and Mg II spectral line parameters used for
the black hole mass (M) estimation for a sample of Type 1 Active
Galactic Nuclei (AGN) spectra selected from the Sloan Digital Sky Survey (SDSS)
database. We have analyzed and compared the virialization of the H and
Mg II emission lines, and found that the H line is more confident virial
estimator than Mg II. We have investigated the influence of the Balmer
continuum emission to the M estimation from the UV parameters, and
found that the Balmer continuum emission can contribute to the overestimation
of the M on average for ~ 5% (up to 10%).Comment: 9 pages, 3 figures, Accepted for publication in Frontiers in
Astronomy and Space Science
The shape of Fe K line emitted from relativistic accretion disc around AGN black holes
The relativistically broadened Fe K line, originating from the
accretion disc in a vicinity of a super massive black hole, is observed in only
less than 50\% of type 1 Active Galactic Nuclei (AGN). In this study we
investigate could this lack of detections be explained by the effects of
certain parameters of the accretion disc and black hole, such as the
inclination, the inner and outer radius of disc and emissivity index. In order
to determine how these parameters affect the Fe K line shape, we
simulated about 60,000 Fe K line profiles emitted from the
relativistic disc.
Based on simulated line profiles, we conclude that the lack of the Fe
K line detection in type 1 AGN could, be caused by the specific
emitting disc parameters, but also by the limits in the spectral resolution and
sensitivity of the X-ray detectors.Comment: Based on the talk presented Balkan Workshop BW2018 (10-14 June 2018,
Ni\v{s}, Serbia), accepted for publishing in International Journal of Modern
Physics A, 8 figures, 1 table, 15 page
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