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: http://www.sao.ru/hq/grb/conf_2015/participants.html
Дата изменения: Unknown Дата индексирования: Sun Apr 10 09:10:03 2016 Кодировка: Windows-1251 Поисковые слова: supernova remnant |
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The International Workshop on
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Participants and presentations
The future next-generation neutrino telescope Baikal-GVD will be a km3-scale
array aimed at detection of astrophysical neutrino fluxes.
It will have a modular structure and consist of functionally independent sub-arrays -
clusters of strings of optical modules. The prototyping phase of
the project has been completed in 2015 with deployment of the first cluster
of Baikal-GVD in the Lake Baikal. We discuss current status and prospects
of the Baikal-GVD project.
Streams of ultracold neutrons are used in experiments on measurement of the dipole moment
of the neutron, and to test the hypothesis of the existence of neutron-antineutron
oscillations with non-conservation of baryon quantum number ΔB = 2.
We tested the possibility of cooling and formation of thermal neutron flux
by a constructive neutron monitor NM - 64 [1] cooled by liquid nitrogen vapors.
For neutron detection in the installation may be used the scintillation method [2]
or proportional counters [3] . We also presented a helium cryostat for
cooling and formation of neutron fluxes. Calculations have been done
for cold neutron flux density by using a cascade generator and reaction t (d, n)
4He at a deuteron energy of 130 keV and for signal/background ratio for various
lengths of neutron-antineutron oscillations in
vacuumed vertically placed pipe with length L ≈ 10 m.
We estimate the energy reservoir available in the deconfinement phase transition
induced collapse of a neutron star to its hybrid star mass twin on the "third family"
branch, using a recent equation of state of dense matter.
The available energy corresponding to the mass-energy difference between configurations
is comparable with energies of the most violent astrophysical burst processes.
An observational outcome of such a dynamical transition might be fast radio bursts,
specifically a recent example of a FRB with a double-peak structure in its light curve.
Results of the search for coincidences of rare events in LVD and Baksan
Underground Scintillation Telescope (BUST) detectors are presented.
We developed a procedure of the search for events in LVD and BUST detectors which could be induced
by interaction between neutrinos and matter contained in them. It was shown that from 2011 to 2014
the coincidences are of random character and their sum quantity remains practically invariable.
Core-collapse of massive stars produces both neutrino signal
and gravitational wave (tensor-transversal plus scalar-longitudinal) bursts.
In the case of GW detectors having low angular resolution the method of
sidereal time analysis of output signals was applied for extraction of GW-bursts
from high level noise. This method was suggested by J.Weber, Phys. Rev. Letters
22, 1320, 1969 for signal analysis of his bar detector and developed
for the case of existing GW detectors in papers by Y.Baryshev and G.Paturel,
A&A, 371, 378, 2001 (arXiv: astro-ph/0104115), P.Astone et al., CQG,
19,5449, 2002 (arXiv: gr-qc/0210053), G.Paturel and Y.Baryshev,
A&A, 398, 377, 2003 (arXiv: astro-ph/0104115), G.Paturel and Y.Baryshev,
ApJ Lett., 592, L99, 2003.
The same sidereal time approach can be also applied for low energy neutrino detectors having many years of observational time (e.g. Super-Kamiokande, LVD, Baksan). This method uses following basic things: 1) difference between sidereal and mean solar time (which help to delete noises related to day-night solar time), 2) directivity diagram (antenna pattern) of the detector (which chooses a particular sky region in particular sidereal time), and 3) known position on the sky the inhomogeneous distribution of the possible sources of SN signals, such as Galactic plane, Galaxy center, closest galaxies, Virgo galaxy cluster, Super-galactic plane, Great Attractor. Main idea is calculation of the expected number of neutrino events as a function of sidereal time (scanning the sky by Earth rotation) produced by possible sources within fixed depth of the survey. The summation of all output signals within one Earth’s revolution (∼23h 56m 04s of mean solar day) during several years of observations will reveal certain structure at predicted sidereal hours (by using directivity pattern of a detector), so the detection has statistical sense.
Recycling scenario imposes important constraints on r-mode instability in neutron stars
and thus on neutron star microphysics. Recent Ref. [1] concluded that
ungapped interacting quark matter model is consistent with recycling scenario,
including radio and x-ray data. However, this model leads to very high neutrino
luminosity, thus high temperatures observed for neutron stars in low mass X-ray
binaries can hardly be explained. On the contrary, our recent model [2] agrees
with these observations, furthermore it is also consistent with neutron star cooling data,
because it appeals to the same microphysical parameters as the minimal cooling model does [3].
Within our model, r-mode instability is suppressed because of the resonant interaction
of oscillation modes at some internal temperatures ("resonant temperatures").
Here we demonstrate that this model agrees as well with observations of millisecond pulsars
and provides observational evidences that the coupling parameter for resonant mode interaction
at low temperatures should be rather large, in agreement with theoretical expectations [2].
This study was partially supported by RFBR (grants 14-02-00868-a and 14-02- 31616-mol-a), and by RF president programme (grants MK-506.2014.2 and NSh-294.2014.2). References [1] M.G. Alford and K. Schwenzer, Phys. Rev. Lett. 113, 251102 (2014). [2] M.E. Gusakov, A.I. Chugunov, and E.M. Kantor, Phys. Rev. Lett. 112, 151101 (2014); Phys. Rev. D 90, 063001 (2014). [3] M.E. Gusakov et al, A&A 423, 1063 (2004); Mon. Not. R. Astron. Soc. 363, 555 (2005).
We present spectral and timing analyses of the X-ray emission from the pulsar wind nebula DA 495
and its central object, J1952.2+2925, suggested to be the pulsar, using archival Chandra and
XMM-Newton data. J1952.2+2925 has a pure thermal spectrum which is equally well fitted either
by the blackbody model with a temperature of 215 eV and an emitting area radius of 0.6?km or
by magnetized neutron star atmosphere models with temperatures of 80-90 eV.
In the latter case, the thermal emission can come from the entire neutron star surface
which temperature is consistent with standard neutron star cooling scenarios.
We place also an upper limit on the J1952.2+2925 non-thermal flux.
The derived spectral parameters are generally compatible with published ones based only
on the Chandra data, but they are much more accurate due to the inclusion of XMM-Newton data.
No pulsations were found and we placed an upper limit for the J1952.2+2925
pulsed emission fraction of 40 per cent. Utilizing the interstellar absorption-distance
relation, we estimated the distance to DA 495, which can be as large as 5 kpc
if J1952.2+2925 emission is described by the atmosphere models. We compiled possible
multiwavelength spectra of the nebula including radio data; they depend on
the spectral model of the central object. Comparing the results with other pulsar
plus wind nebula systems, we set reasonable constraints on the J1952.2+2925
spin-down luminosity and age. We suggest that the Fermi source 3FGL J1951.6+2926 is
the likely gamma-ray counterpart of J1952.2+2925.
We perform the analysis of a data set of Baikal neutrino telescope
NT200 to search for neutrino signals from dark matter annihilation
in the Galactic Center and in Dwarf Galaxies. From this analysis
we set upper limits on dark matter annihilation cross sections for
different annihilation channels. Also we discuss sensitivity of the
gigaton volume telescope Baikal-GVD to this signal.
I will review the two-families scenario in which hadronic stars having rather small radii and masses
not exceeding about 1.5 Ms coexist with quark stars, which can reach masses well above 2 Ms.
I will discuss the implications of this scenario in particular for long and short GRBs, using the results
of our recent work in which the process of quark deconfinement in compact stars has been revisited.
Bibliographical references: 1) "Can very compact and very massive neutron stars both exist?" by Alessandro Drago, Andrea Lavagno, Giuseppe Pagliara. Phys.Rev. D89 (2014) 4, 043014. 2) "Early appearance of Δ isobars in neutron stars" by Alessandro Drago, Andrea Lavagno, Giuseppe Pagliara, Daniele Pigato. Phys.Rev. C90 (2014) 6, 065809. 3) "Combustion of a hadronic star into a quark star: the turbulent and the diffusive regimes" by Alessandro Drago, Giuseppe Pagliara. arXiv:1506.08337 4) "Quark deconfinement and the duration of short Gamma Ray Bursts" by Alessandro Drago, Andrea Lavagno, Giuseppe Pagliara In preparation
We analyze Carpet-2 EAS array data in order to search for events with
anomalously low content of muons with energies Eμ > 1 GeV in extensive
air showers with energy above 100 TeV. Monte-Carlo simulations of showers
induced by primary protons and gammas have been performed using the CORSIKA code.
The estimation of the upper limit on the flux primary gamma rays is presented.
Radiochemical neutrino detectors have played an important role in the study
of neutrinos from the Sun. Features of radiochemical detectors - no external
backgrounds and sensitivity only to electron neutrinos - make them
a powerful tool for precision measurements of neutrino properties
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