13,819 research outputs found
Scenarios for GCRT J1745-3009
I discuss several scenarios to explain properties of the radio transient
source GCRT J1745-3009. Namely, a highly magnetized neutron star on the
propeller or georotator stage, a transient propeller, and an ejector in a
binary system are discussed. Simple populational estimates favor the transient
propeller model.Comment: 8 pages, no figures, Talk at the conference "VA100 Evolution of
Cosmic Objects Through Their Physical Activity", Yerevan, Armenia 2008. Subm.
to the proceeding
Magneto-rotational and thermal evolution of young neutron stars
After a brief review of population synthesis of close-by cooling neutron
stars, I focus on the interpretation of dichotomy of spin periods of near-by
coolers. The existence of two well separated groups -- short period
(0.1-0.3 s) radio pulsars and long period (3-10 s) radio quiet
sources, aka the Magnificent seven, -- can not be easily explained in unified
models developed recently (Popov et al. 2010, Gull{\'o}n et al. 2014). I
speculate that the most natural solution of the problem can be in bimodal
initial magnetic field distribution related to the existence of an additional
mechanism of field generation in magnetars.Comment: 6 pages, proceedings of STARS201
On the mechanism of low-mass compact object formation
We suggest that low-mass compact objects (hadron stars, quark stars) with
can appear only due to fragmentation of rapidly rotating
proto-neutron stars. Such low-mass stars receive large kicks due to an
explosion of a lighter companion in a pair of fragments, or due to dynamical
ejection of one of the lighter components in the case when three bodies are
formed.
As far as low-mass compact objects are expected to be slowly cooling in all
popular models of thermal evolution possible candidates are expected to be
found among hot high velocity sources.Comment: 4 pages, no figure
Old isolated neutron stars
In this poster I briefly review several articles on astrophysics of old
isolated neutron stars, which were published in 1994-99 by my co-authors and
myself.Comment: 9 pages, 9 PostScript figure
Close by Compact Objects and Recent Supernovae in the Solar Vicinity
I discuss young close-by compact objects, recent supernovae in the solar
neighbourhood, and point to their connection with cosmic ray studies.
Especially the role of the Gould Belt is underlined.Comment: 12 pages, proceedings of the International School of Cosmic Ray
Astrophysics, 14th Course: "Neutrinos and Explosive Events in the Universe
Origin of magnetars in binary systems
I review several scenarios of magnetar formation in binary systems via
spin-up of a progenitor due to interaction with its companion. Mostly, these
evolutionary channels lead to formation of isolated magnetars, and indeed, all
well-established sources of this class are single objects. However, some
binaries can survive, and several candidates to accreting magnetars have been
proposed. I discuss this issue, and conclude that new accretion models can
explain properties of the proposed candidates without large magnetic field in
correspondence with models of magnetic field evolution.Comment: 10 pages, no figures, based on a talk presented at "Ioffe Workshop on
GRBs and other transient sources: 20 Years of Konus-Wind Experiment", subm.
to a special issue of Astron. Astrophys. Tran
Origin of magnetar-scale crustal field in PSR J1852+0040 and "frozen" magnetars
We discuss the origin of strong crustal magnetic field in one of central
compact objects (CCOs) --- a neutron star PSR J1852+0040 in the supernova
remnant Kes 79. Taking into account its relatively long present day spin period
we conclude that the field could not be generated via a dynamo mechanism. If
this neutron star indeed is a magnetar with field submerged during a strong
fall-back episode, then it argues against the dynamo field origin in magnetars.
Otherwise, Kes 79 is not a close relative of normal magnetars. A discovery of
an anti-magnetar with a millisecond period and strong crustal field
identifiable, for example, due to large pulse fraction, would be the proof of
the dynamo field origin. Existence of such sources is in correspondence with
the present standard picture of neutron star unification. However, the fraction
of magnetars with submerged fields can be small --- few percent of the total
number of CCOs.Comment: 4 pages, accepted for publication in PAS
A parameter to quantify dynamics of a researcher's scientific activity
I propose the coefficient, , and its modification which in a
simple way reflect dynamics of scientific activity of an individual researcher.
I determine as a time period (from some moment in the past till the
present moment) during which papers responsible for 1/2 of the total citation
index were published. Parameter represents average of the citation index
over this period: .Comment: 4 pages including 2 figures, article styl
The Zoo of Neutron Stars
In these lecture notes I briefly discuss the present day situation and new
discoveries in astrophysics of neutron stars focusing on isolated objects. The
latter include soft gamma repeaters, anomalous X-ray pulsars, central compact
objects in supernova remnants, the Magnificent seven, and rotating radio
transients. In the last part of the paper I describe available tests of cooling
curves of neutron stars and discuss different additional constraints which can
help to confront theoretical calculations of cooling with observational data.Comment: 12 pages, no figures. To appear in the proceedings of the summer
school "Dense Matter In Heavy Ion Collisions and Astrophysics" in a separate
volume of Particles and Nuclei, Letter
What is the nature of the central compact X-ray source in the supernova remnant RCW 103
In this poster I discuss the nature of the compact X-ray source in the center
of the supernova remnant RCW 103. Several models, based on the accretion onto a
compact object such as a neutron star or a black hole (isolated or binary), are
analyzed. I show that it is more likely that the central X-ray source is an
accreting neutron star than an accreting black hole. I also argue that models
of a disrupted binary system consisting of an old accreting neutron star and a
new one observed as a 69-ms X-ray and radio pulsar are most favored.Comment: 8 pages, no figures, to be presented as a poster at the conference
"Non-accelerator particle astrophysics" 29 June - 10 July 1998, Trieste,
Italy. In the replaced version a short note about earlier discussion by Torii
et al. was adde
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