The Birthrate of Magnetars

Magnetars, neutron stars with ultra strong magnetic fields ($B\sim 10^{14} - 10^{15}$G), manifest their exotic nature in the form of soft gamma-ray repeaters and anomalous X-ray pulsars. This study estimates the birthrate of magnetars to be $\sim$ 0.22 per century with a galactic population comprising of $\sim$17 objects. A population synthesis was carried out based on the five anomalous X-ray pulsars detected in the ROSAT All-Sky Survey by comparing their number to that of massive OB stars in a well defined volume. Additionally, the group of seven X-ray dim isolated neutron stars detected in the same survey were found to have a birthrate of $\sim$ 2 per century with a galactic population of $\sim$ 22,000 objects.Comment: 8 pages, 3 figures, changes to reflect version accepted by Monthly Notices of the Royal Astronomical Societ

Quark-nova remnants III:Application to RRATs

This is the third paper of a series of papers where we explore the evolution of iron-rich ejecta from quark-novae. In the first paper, we explored the case where a quark-nova ejecta forms a degenerate shell, supported by the star's magnetic field, with applications to SGRs. In the second paper we considered the case where the ejecta would have sufficient angular momentum to form a degenerate Keplerian torus and applied such a system to two AXPs, namely 1E2259 + 586 and 4U0142 + 615. Here we explore the late evolution of the degenerate torus and find that it can remain unchanged for $\sim 10^{6}$ years before it becomes non-degenerate. This transition from a degenerate torus (accretion dominated) to a non-degenerate disk (no accretion), occurs about $10^{6}$ years following the quark-nova, and exhibits features that are reminiscent of observed properties of RRATs. Using this model, we can account for the duration of both the radio bursts and the quiet phase, as well as the observed radio flux from RRATs. The unique on and off activity of the radio pulsar PSR B1931 + 24 is similar to that of "old RRATs" in our model. For old RRATs, in our model, the spin-down rate during the radio loud phase is about a factor 1.6 larger than when it is quiet, remarkably similar to what has been measured for PSR B1931 + 24. We discuss a connection between XDINs and RRATs and argue that some XDINs may be ``dead RRATs'' that have already consumed their non-degenerate disk.Comment: submitted to A&

Isolated neutron stars and studies of their interiors

In these lectures presented at Baikal summer school on physics of elementary particles and astrophysics 2011, I present a wide view of neutron star astrophysics with special attention paid to young isolated compact objects and studies of the properties of neutron star interiors using astronomical methods.Comment: 28 pages, lecture notes for the Baikal-2011 summer school on physics of elementary particles and astrophysic

Magnetars, Gamma-ray Bursts, and Very Close Binaries

We consider the possible existence of a common channel of evolution of binary systems, which results in a gamma-ray burst during the formation of a black hole or the birth of a magnetar during the formation of a neutron star. We assume that the rapid rotation of the core of a collapsing star can be explained by tidal synchronization in a very close binary. The calculated rate of formation of rapidly rotating neutron stars is qualitatively consistent with estimates of the formation rate of magnetars. However, our analysis of the binarity of newly-born compact objects with short rotational periods indicates that the fraction of binaries among them substantially exceeds the observational estimates. To bring this fraction into agreement with the statistics for magnetars, the additional velocity acquired by a magnetar during its formation must be primarily perpendicular to the orbital plane before the supernova explosion, and be large.Comment: 16 pages, 4 figure

Strongly magnetized pulsars: explosive events and evolution

Well before the radio discovery of pulsars offered the first observational confirmation for their existence (Hewish et al., 1968), it had been suggested that neutron stars might be endowed with very strong magnetic fields of $10^{10}$-$10^{14}$G (Hoyle et al., 1964; Pacini, 1967). It is because of their magnetic fields that these otherwise small ed inert, cooling dead stars emit radio pulses and shine in various part of the electromagnetic spectrum. But the presence of a strong magnetic field has more subtle and sometimes dramatic consequences: In the last decades of observations indeed, evidence mounted that it is likely the magnetic field that makes of an isolated neutron star what it is among the different observational manifestations in which they come. The contribution of the magnetic field to the energy budget of the neutron star can be comparable or even exceed the available kinetic energy. The most magnetised neutron stars in particular, the magnetars, exhibit an amazing assortment of explosive events, underlining the importance of their magnetic field in their lives. In this chapter we review the recent observational and theoretical achievements, which not only confirmed the importance of the magnetic field in the evolution of neutron stars, but also provide a promising unification scheme for the different observational manifestations in which they appear. We focus on the role of their magnetic field as an energy source behind their persistent emission, but also its critical role in explosive events.Comment: Review commissioned for publication in the White Book of "NewCompStar" European COST Action MP1304, 43 pages, 8 figure

Upper Limits on X-ray Emission from Two Rotating Radio Transients

X-ray emission from the enigmatic Rotating RAdio Transients (RRATs) offers a vital clue to understanding these objects and how they relate to the greater neutron star population. An X-ray counterpart to J1819-1458 is known, and its properties are similar to those of other middle-aged (0.1 Myr) neutron stars. We have searched for X-ray emission with Chandra/ACIS at the positions of two RRATs with arcsecond (or better) localisation, J0847-4316 and J1846-0257. Despite deep searches (especially for J1847-0257) we did not detect any emission with 0.3-8 keV count-rate limits of 1 counts/ks and 0.068 counts/ks, respectively, at 3sigma confidence. Assuming thermal emission similar to that seen from J1819-1458 (a blackbody with radius of approximately 20 km), we derive effective temperature limits of 77 eV and 91 eV for the nominal values of the distances and column densities to both sources, although both of those quantities are highly uncertain and correlated. If we instead fix the temperature of the emission (a blackbody with kT=0.14 keV), we derive unabsorbed luminosity limits in the 0.3-8 keV range of 1e32 erg/s and 3e32 erg/s. These limits are considerably below the luminosity of J1819-1458 (4e33 erg/s), suggesting that RRATs J0847-4316 and J1846-0257 have cooled beyond the point of visibility (plausible given the differences in characteristic age). However, as we have not detected X-ray emission, it may also be that the emission from RRATs J0847-4316 and J1846-0257 has a different character from that of J1819-1458. The two non-detections may prove a counterpoint to J1819-1458, but more detections are certainly needed before we can begin to derive general X-ray emission properties for the RRAT populations.Comment: 7 pages, 2 figures, 1 table, accepted by MNRA

Economic Ideas and Institutional Change: Evidence from Soviet Economic Discourse 1987-1991

In recent years, institutional and evolutionary economists have become increasingly aware that ideas play an important role in economic development. In the current literature, the problem is usually elaborated upon in purely theoretical terms. In the present paper it is argued that ideas are always also shaped by historical and cultural factors. Due to this historical and cultural specificity theoretical research must be supplemented by historical case studies. The paper analyses the shift in ideas that took place in Soviet economic thought between 1987 and 1991. This case study, it is argued, may contribute to our understanding of the links between ideas and institutions. More specifically, it sheds new light on the issue of whether the evolution of economic ideas is pathdependent, so that they change only incrementally, or whether their development takes place in a discontinuous way that can best be compared with revolutions

The Rebellion Against Keynesianism: Milton Friedman

Our journal is continuing to introduce the readers to Nobel Prize winners in economics. The present issue publishes an abstract of a collection of Milton Friedman's selected works.

Economic Reform in the Country and the Capital

At the request of Ekonomika i zhizn readers, G. Popov, mayor of Moscow and chairman of the Russian Democratic Reform Movement (RDRM), shares his views of the current socioeconomic situation.