3,515 research outputs found
On the detection of point sources in Planck LFI 70 GHz CMB maps based on cleaned K-map
We use the Planck LFI 70GHz data to further probe point source detection
technique in the sky maps of the cosmic microwave background (CMB) radiation.
The method developed by Tegmark et al. for foreground reduced maps and the
Kolmogorov parameter as the descriptor are adopted for the analysis of Planck
satellite CMB temperature data. Most of the detected points coincide with point
sources already revealed by other methods. However, we have also found 9 source
candidates for which still no counterparts are known.Comment: 11 pages, 3 figures, Accepted for publication in Modern Physics
Letters A. arXiv admin note: substantial text overlap with arXiv:1206.712
On the theory of coherent pair production in crystals in presence of acoustic waves
The influence of hypersonic waves excited in a single crystal is investigated
on the process of electron-positron pair creation by high-energy photons. The
coherent part of the corresponding differential cross-section is derived as a
function of the amplitude and wave number of the hypersound. The values of the
parameters are specified for which the latter affects remarkably on the pair
creation cross-section. It is shown that under certain conditions the presence
of hypersonic waves can result in enhancement of the process cross-section.Comment: 10 pages, 3 EPS figure
Radiation from a charged particle-in-flight from a laminated medium to vacuum
The radiation from a charged particle-in-flight from a semi-infinite
laminated medium to vacuum and back,- from vacuum to the laminated medium, has
been investigated. Expressions for the spectral-angular distribution of
radiation energy in vacuum (at large distances from the boundary of laminated
medium) were obtained for both the cases with no limitations on the amplitude
and variation profile of the laminated medium permittivity. The results of
appropriate numerical calculations are presented and possible applications of
the obtained results are discussed.Comment: 8 pages, 6 figures, contribution to Proceedings of International
Symposium RREPS-2009, 07-11 September, 2009, Zvenigorod, Russi
To the center of cold spot with Planck
The structure of the cold spot, of a non-Gaussian anomaly in the cosmic
microwave background (CMB) sky first detected by Vielva et al. is studied using
the data by Planck satellite. The obtained map of the degree of stochasticity
(K-map) of CMB for the cold spot, reveals, most clearly in 100 GHz band, a
shell-type structure with a center coinciding with the minima of the
temperature distribution. The shell structure is non-Gaussian at a 4\sigma
confidence level. Such behavior of the K-map supports the void nature of the
cold spot. The applied method can be used for tracing voids that have no
signatures in redshift surveys.Comment: A & A (in press), 4 pages, 5 figures; to match the published versio
Excitation of nonlinear two-dimensional wake waves in radially-nonuniform plasma
It is shown that an undesirable curvature of the wave front of
two-dimensional nonlinear wake wave excited in uniform plasma by a relativistic
charged bunch or laser pulse may be compensated by radial change of the
equilibrium plasma density.Comment: 6 pages, 4 figure
Triangulum galaxy viewed by Planck
We used Planck data to study the M33 galaxy and find a substantial
temperature asymmetry with respect to its minor axis projected onto the sky
plane. This temperature asymmetry correlates well with the HI velocity field at
21 cm, at least within a galactocentric distance of 0.5 degree, and it is found
to extend up to about 3 degrees from the galaxy center. We conclude that the
revealed effect, that is, the temperature asymmetry and its extension, implies
that we detected the differential rotation of the M33 galaxy and of its
extended baryonic halo.Comment: 8 pages, 8 figures, in press on Astronomy and Astrophysics, main
journa
Planck's confirmation of the M31 disk and halo rotation
Planck's data acquired during the first 15.4 months of observations towards
both the disk and halo of the M31 galaxy are analyzed. We confirm the existence
of a temperature asymmetry, previously detected by using the 7-year WMAP data,
along the direction of the M31 rotation, therefore indicative of a
Doppler-induced effect. The asymmetry extends up to about 10 degrees (about 130
kpc) from the M31 center. We also investigate the recent issue raised in Rubin
and Loeb (2014) about the kinetic Sunyaev-Zeldovich effect from the diffuse hot
gas in the Local Group, predicted to generate a hot spot of a few degrees size
in the CMB maps in the direction of M31, where the free electron optical depth
gets the maximum value. We also consider the issue whether in the opposite
direction with respect to the M31 galaxy the same effect induces a minimum in
temperature in the Planck's maps of the sky. We find that the Planck's data at
100 GHz show an effect even larger than that expected.Comment: 4 pages, 1 table, 2 figures, in press as a Letter in A&
Planck view of the M82 galaxy
Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz
bands. A substantial north-south and East-West temperature asymmetry is found,
extending up to 1 degree from the galactic center. Being almost
frequency-independent, these temperature asymmetries are indicative of a
Doppler-induced effect regarding the line-of-sight dynamics on the halo scale,
the ejections from the galactic center and, possibly, even the tidal
interaction with M81 galaxy. The temperature asymmetry thus acts as a
model-independent tool to reveal the bulk dynamics in nearby edge-on spiral
galaxies, like the Sunyaev-Zeldovich effect for clusters of galaxies.Comment: 4 pages, 3 figures, in press on A&
Planck revealed bulk motion of Centaurus A lobes
Planck data towards the active galaxy Centaurus A are analyzed in the 70, 100
and 143 GHz bands. We find a temperature asymmetry of the northern radio lobe
with respect to the southern one that clearly extends at least up to 5 degrees
from the Cen A center and diminishes towards the outer regions of the lobes.
That transparent parameter - the temperature asymmetry - thus has to carry a
principal information, i.e. indication on the line-of-sight bulk motion of the
lobes, while the increase of that asymmetry at smaller radii reveals the
differential dynamics of the lobes as expected at ejections from the center.Comment: 4 pages, 3 figures, Astronomy & Astrophysics, Letter to the Editor
(in press
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