Search

General relativity has predicted the existence of gravitational waves (GW), which are waves of the distortions of space-time with two degrees of polarization and the propagation speed of light. Alternative theories predict more polarizations, up to a maximum of six, and possible deviation of propagation speed from the light speed. The present paper reviews recent proposals to test the gravity theories in the radiation regime by observing GWs using pulsar timing arrays., Comment: 4 pages, 2 figures, PULSAR CONFERENCE 2010, Chia Laguna Resort, Sardinia, Italy, 10-15 October, 2010

Radio giant pulses provide a unique opportunity to study the pulsar radio emission mechanism in exquisite detail. Previous studies have revealed a wide range of properties and phenomena, including extraordinarily high brightness temperatures, sub-nanosecond emission features, and banded dynamic spectra. New measurements of giant pulse characteristics can help guide and test theoretical emission models. To this end, an extensive observation campaign has begun which will provide more than 500 hours on the Crab with a 34-meter antenna located in California, USA. The observations are being done as part of an educational outreach program called the Goldstone-Apple Valley Radio Telescope (GAVRT). This antenna has a novel wide bandwidth receiver which provides up to 8 GHz of instantaneous bandwidth in the range of 2.5 to 14 GHz. These observations will provide detailed information about the variability, amplitude distribution, and detailed frequency structure of radio giant pulses. In addition, a database of pulses from these observations and others of the Crab pulsar is being created which will simplify multiwavelength correlation analysis., Comment: 4 pages, 1 figure. AIP Conference Proceedings of Pulsar Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe", Sardinia, October 2010

With a distance of 170 pc, PSR J2144-3933 is the closest isolated radio pulsar currently known. It is also the slowest and least energetic radio pulsar; indeed, its radio emission is difficult to account for with standard pulsar models, since its position in the P-Pdot diagram is far beyond typical "death lines". Here we present the first deep X-ray and optical observations of PSR J2144-3933, performed in 2009 with XMM-Newton and the VLT, from which we can set one of the most robust upper limits on the surface temperature of a neutron star. We have also explored the possibility of measuring the neutron star mass from the gravitational lensing effect on a background optical source., 4 pages, 3 figures; to appear in the Proceedings of the Pulsar Conference 2010, Chia, Sardinia (Italy), 10-15 October 2010

We compare population synthesis results for inner and outer magnetosphere emission models with the various characteristics measured in the first LAT pulsar catalogue for both the radio-loud and radio-weak or radio-quiet gamma-ray pulsars. We show that all models fail to reproduce the observations: for each model there is a lack of luminous and energetic objects that suggest a non dipolar magnetic field structure or spin-down evolution. The large dispersion that we find in the simulated gamma-ray luminosity versus spin-down power relation does not allow to use the present trend seen in the Fermi data to distinguish among models. For each model and each Fermi detected pulsar, we have generated light curves as a function of obliquity and inclination angles. The theoretical curves were fitted to the observed one, using a maximum-likelihood approach, to derive the best-fit orientations and to compare how well each model can reproduce the data. Including the radio light-curve gives an additional key constraint to restrict the orientation space, 4 pages, 3 figures, to appear in the proceedings of the Pulsar 2010 Conference, Italy, 10 - 15 October 2010

We present results of our pulsar population synthesis of normal pulsars from the Galactic disk using our previously developed computer code. On the same footing, we use slot gap and outer gap models for gamma-ray emission from normal pulsars to obtain statistics of radio-loud and radio-quiet gamma-ray pulsars. From recently improved understanding of HII and star forming regions in the Galaxy, we develop a new surface density model of the birth location of neutron stars. We explore models of neutron star evolution with magnetic field-decay, and with different initial period and magnetic field distributions. We present preliminary results including simulated population statistics that are compared with recent detections by Fermi of normal, isolated pulsars., 4 pages, 3 figures, to appear in the proceedings of the Pulsar 2010 Conference, Italy, 10 - 15 October 2010

We present the radio observations of two isolated neutron stars: XDINS 1RXS J1308.6+212708 and 1RXS J214303.7+065419. The observations were carried out on two sensitive transit radio telescopes at a few low frequencies with using new digital receiver. We have obtained pulse profiles and dynamic spectra and have estimated the main parameters of radio emission for two objects. Results of the correlation analysis of data, allowing to define a dispersion measure by independent method, are given as well. Comparison with X‐ray data shows large differences in the mean pulse widths and luminosities.

The Parkes multi‐beam pulsar survey (PMPS) [1] is the most successful pulsar survey ever undertaken, discovering 786 pulsars (including those from this work) and 30 RRATs (e.g. [2] and references therein). Previous analyses of the survey have not been fully sensitive to relativistic binary systems, where the spin period of the pulsar varies significantly over the duration of the 35 minute observations because of the Doppler effect. The aim of this latest re‐analysis was to partially combat such selection effects and to find any relativistic binary systems that were missed in previous searches. In total 16 pulsars have been discovered including one MSP binary and a possible intermittent pulsar.

We present the status of the Sardinia Radio Telescope (SRT) project, a new general purpose, fully steerable 64 m diameter parabolic radio telescope under construction in Sardinia. The instrument is funded by Italian Ministry of University and Research (MIUR), by the Sardinia Regional Government (RAS), and by the Italian Space Agency (ASI), and it is charge to three research structures of the National Institute for Astrophysics (INAF): the Institute of Radio Astronomy of Bologna, the Cagliari Astronomical Observatory (in Sardinia), and the Arcetri Astrophysical Observatory in Florence. The radio telescope has a shaped Gregorian optical configuration with a 8 m diameter secondary mirror and additional Beam‐Wave Guide (BWG) mirrors. One of the most challenging feature of SRT is the active surface of the primary reflector which provides good efficiency up to about 100 GHz. This paper reports on the most recent advances of the construction.

The Square‐Kilometre‐Array (SKA) represents the future of radio astronomy and will have a profound impact on a wide range of science. In particular, it will completely change the field of pulsar astronomy, providing not only a vast number of sources that can be studied but will also deliver an unprecedented sensitivity and timing precision for such studies. The result will be applications impossible with current technology, for example, in the field of gravitational physics. With the SKA we will study the nHz‐gravitational wave sky, will probe the properties of gravitational waves and will also establish the properties of black holes.

The last few years have seen a revolution in very high γ‐ray astronomy (VHE; E>100 GeV) driven largely by a new generation of Cherenkov telescopes. These new facilities, namely H.E.S.S. (High Energy Stereoscopic System), MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescope) and its upgrade MAGIC 2, Veritas (Very Energetic Radiation Imaging Telescope Array System) and CANGAROO (Collaboration of Australia and Nippon for a Gamma Ray Observatory in the Outback) were designed to increase the flux sensitivity in the energy regime of hundreds of GeV, expanding the observed energy range from 100 (50) GeV to multi‐TeV, and fostered as a result a period of rapid growth in our understanding of the Non‐Thermal Universe. As a result of this fast development the number of pulsar wind nebulae (PWNe) detected has increased from a few in the early 90’s to more than two dozen of firm candidates nowadays. A review of the most relevant VHE results concerning pulsars and their relativistic winds is discussed here in the...

In this project single pulse energy histograms of five pulsars in three different wavelengths—2.8 cm, 6 cm, 21 cm‐were constructed. Not only have we constructed the ON‐pulse histograms, but also the histograms of individual components. Furthermore we have estimated the fraction of null pulses for the ON‐pulse window and for each component individually.

Observations of twelve newly discovered pulsars were performed at 610 MHz using GMRT. We have found some candidates for pulsars with Gigahertz‐Peaked Spectra (GPS) with PSR J1705−3950 and PSR J1852−0635 being the most promising.

Pulsars, and more in general rotating neutron stars, are expected to permanently emit gravitational waves, mainly at the double of the rotational frequency. This type of signals requires long observation times in order to distinguish the peak at the emission frequency in the antenna signal spectrum from the incoherent noise floor. The energy of the signal spectral peak is smeared by the Doppler phase modulation due to the antenna motion with respect to the source and by the phase shift induced by the source rotational frequency slowing because of energy losses due to emissions. The correction to these effects requires, in general, the knowledge of the source emission frequency, of the spin‐down and of the source sky position. We propose a very effective method to compensate for Doppler and spin‐down. The technique is particularly useful for semi‐targeted searches. It consists in a fast resampling of the antenna signal aimed to synchronize with a large accuracy the detector time with the source one. The ap...

We present the new pulsars discovered in the 350‐MHz survey with the Green Bank Telescope. The survey took advantage of the time available during the track refurbishing during the Northern hemisphere summer of 2007. So far we have discovered 26 new pulsars, including 5 millisecond pulsars, 6 binary pulsars, and 1 rotating radio transient in the 1491 hours of data. Many exciting pulsars have been discovered but in the present work together with the survey overview we highlight only one pulsar, J2222−0137, a pulsar with a minimum mass companion of 1.1 M⊙ and the second lowest dispersion measure of any known binary pulsar.

γ‐ray telescopes cannot focus incident high‐energy radiation, and the background emission from sources nearby in projection can obscure the periodic emission from pulsars, making unambiguous detection of pulsations difficult. In the context of the Fermi Large Area Telescope (LAT), we present modified statistical tests for periodicity in which each photon is weighted by its probability to have originated from the candidate pulsar. Since the probabilities are calculated using the instrument response function and a full spectral model, they provide powerful background rejection. With Monte Carlo methods, we demonstrate that the new tests increase the sensitivity to pulsars by more than 50% under a wide range of conditions.

The ∼800 yr‐old pulsar PSR J1846‐0258 in the supernova remnant Kes 75 is a unique transition object between rotation‐powered pulsars and magnetars. While it typically behaves as a rotation‐powered pulsar, in 2006 it exhibited a distinctly magnetar‐like outburst accompanied by a large glitch with an unusual over‐recovery. We present X‐ray timing observations taken with the Rossi X‐ray Timing Explorer after the X‐ray outburst and accompanying glitch had recovered. We observe that the braking index of the pulsar, previously measured to be n = 2.65±0.01 has decreased by 18±5%. We also note a persistent increase in the timing noise relative to the pre‐outburst level, reminiscent of behavior previously observed from some magnetars.

An intriguing paper has recently been published claiming that the long‐sought Rosetta Stone needed to decipher the nature of pulsar radio emission has been finally identified as the bifurcated features in averaged pulsar profiles. The authors argued that highly symmetric bifurcated features observed in PSR J1012+5307 and other pulsars are produced by a split‐fan beams of extraordinary‐mode curvature radiation emitted by thin streams of sources conducted by a very narrow bundles of magnetic field lines. We examined the arguments leading to such a profound conclusion and found at least one fatal flaw. Using an elementary pulsar physics we showed that there is not enough energy to power the bifurcated feature in J1012+5307 within a split‐fan beams model. If the source streams are indeed so thin that their emission can reveal the signatures of elementary radiation mechanism, then the energy deficit reaches several orders of magnitude.

Soft gamma-ray repeaters and anomalous X-ray pulsars are a small (but growing) group of X-ray sources characterized by the emission of short bursts and by a large variability in their persistent flux. They are believed to be magnetars, i.e. neutron stars powered by extreme magnetic fields 1E14-1E15 G). We found evidence for a magnetar with a low magnetic field, SGR 0418+5729, recently detected after it emitted bursts similar to those of soft gamma-ray repeaters. New X-ray observations show that its dipolar magnetic field cannot be greater than 8E12 G, well in the range of ordinary radio pulsars, implying that a high surface dipolar magnetic field is not necessarily required for magnetar-like activity. The magnetar population may thus include objects with a wider range of magnetic-field strengths, ages and evolutionary stages than observed so far., Comment: 4 pages, 2 figures; to appear in the Proceedings of the Pulsar Conference 2010, Chia, Sardinia (Italy), 10-15 October 2010

“Tsubame” is a university‐built small satellite mission that measures polarization of hard X‐ray photons (30–100 keV) from gamma‐ray bursts (GRB) using azimuthal angle anisotropy of Compton scattering. The satellite is intended for a piggy‐back launch on the H‐IIA rocket. It uses Control moment gyros to quickly orient itself to GRBs within 15 seconds from triggers. We are now developing the engineering model of the two detector systems on Tsubame, the polarimeter and the bust monitor. In this paper, we present an overview of the Tsubame mission, and detail of development of engineering model of our polarimeter and burst monitor.

The recycling model argues the existence of an evolutionary connection between low mass X-ray binaries and radio millisecond pulsars. The main difficulties which this model finds in predict the parameters of the fully recycled millisecond pulsars, as mass and spin period, can be overcome by the onset of the so-called radio-ejection mechanism. This work is to provide observational support to the radio-ejection mechanism by inspecting the orbital and spin parameters of the known population of fully recycled radio pulsars and compare these with the expectation for the occurrence of this mechanism.

Terzan5 is the globular cluster (GC)-like stellar system harboring the largest known population of MSPs. Using the Multi-Conjugate Adaptive Optics demonstrator MAD at the ESO - VLT, we recently obtained a superb (K, J - K) color-magnitude diagram, which has revealed the existence of two horizontal branches (HBs) well separated in magnitude and colour (Ferraro et al. 2009, Nature,462, 483). A prompt spectroscopic follow-up with NIRSPEC@Keck has shown that the two populations have (1) significantly different iron content ([Fe/H]= -0.2 and +0.3 for the faint and the bright HB, respectively), (2) distinct [alpha/Fe] abundance patterns and (3) no evidence of the Al-O anti-correlation commonly observed in GCs. All these properties suggest that Ter 5 is far from being a genuine globular. Instead it has experienced the explosion of a huge number of supernovae (SNe), thus accounting for its high metal content and it should have been much more massive in the past than today, thus to retain the SN ejecta within its potential well. The many type II SNe should have also produced a large number of neutron stars (NSs), which could finally explain its exceptionally large population of MSPs., Comment: Contributed Talk at the conference "Radio Pulsars: a key to unlock the secrets of the Universe", Baia Chia, Sardinia, Italy, 11-15 Oct. 2010, 4 pages, 2 figures

Don Backer was a true founding father of pulsar astronomy, a dedicated and passionate scientist who, alongside a career of tremendous and varied scientific accomplishment, was friendly, easy‐going, dignified, and kind. This tribute summarizes Don’s work, highlighting his many contributions to pulsar astronomy and other fields.

To search for extragalactic pulsars we carried out observations of six nearby galaxies at 820 MHz with the 100‐m Robert C. Byrd Green Bank radio telescope. All target galaxies of the Local Group are at high galactic latitudes |b|>30°, that provides much less Galactic contribution to dispersion measures of extragalactic pulsars, and is crucial to detect them. In the present work we report about our preliminary results.

We describe our studies of the radio and high-energy properties of Rotating Radio Transients (RRATs). We find that the radio pulse intensity distributions are log-normal, with power-law tails evident in two cases. For the three RRATs with coverage over a wide range of frequency, the mean spectral index is -1.7\pm0.1, roughly in the range of normal pulsars. We do not observe anomalous magnetar-like spectra for any RRATs. Our 94-ks XMM-Newton observation of the high magnetic field RRAT J1819-1458 reveals a blackbody spectrum (kT ~130 eV) with an unusual absorption feature at ~1 keV. We find no evidence for X-ray bursts or other X-ray variability. We performed a correlation analysis of the X-ray photons with radio pulses detected in concurrent observations with the Green Bank, Effelsberg, and Parkes telescopes. We find no evidence for any correlations between radio pulse emission and X-ray photons, perhaps suggesting that sporadicity is not due to variations in magnetospheric particle density but to changes in beaming or coherence., 4 pages, 2 figures, to appear in AIP Conference Proceedings of Pulsar Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe", Sardinia, October 2010

We report a discovery of a phase‐related subpulse drift pattern in the relatively less studied pulsar, B1039−19, using high sensitivity GMRT observations at 325 MHz. We observe simultaneous occurrence of four/three drift regions—evident subpulse drifting under the leading and the trailing peaks, less evident subpulse drifting under the small peak near to the leading peak and under the inner saddle region. Subpulse drifting in all the four regions appear to be locked in phase.

Observational evidences of erratic 1(st) harmonic pulse phase shifts in accreting millisecond X-ray pulsars pulse phase evolution was reported by several authors. This effect always go together with much more stable 2(nd) harmonics pulse phase delays. Different possible explanations of these phase shifts have been given in literature. But all these interpretations do not explain why the 2(nd) harmonic are more stable than the 1(st) harmonic. The explanation of such a behaviour is of fundamental importance in order to gain an insight on the NS rotational behaviour and to remove the still present interpretative ambiguity on the results of timing analysis. We propose a simple toy-model to interpret these phenomena as effect of small variations of the ratio between the fluxes from the two hot-spots. We show how it affects the phase of the overall pulse profile, when the two amplitudes are similar and the two hot-spots are not perfectly antipodal. Using this model, we give a detailed explanation of the phase jump observed in the 2002 outburst of SAX J1808.4-3658.

We have built two single photon very high speed photometers (AquEYE for the Asiago 1.8 m telescope and IquEYE for the 3.5 m ESO NTT) as prototypes of a quantum photometer for the 42 m European Extremely Large Telescope (E‐ELT). The two photometers are the most accurate time machines available to optical astronomy. The arrival time of each detected photon is referenced to UTC with a precision better than 500 picoseconds, continuously for hours of data acquisition. We report timing results for three optical pulsars.

We report on a new 3D fully relativistic, modular, parallel and scalable Particle‐In‐Cell (PIC) code currently being developed at the Computational Astrophysics Laboratory in the National University of Ireland, Galway and its initial test applications to the plasma distribution in the vicinity of a rapidly rotating neutron star. We find that Plasma remains confined by trapping surfaces close to the star as opposed to propagating to a significant portion of the light‐cylinder distance as predicted in this early work. We discuss planned future modifications and applications of the developed code.

When the line of sight of a pulsar is close to the Sun, the electron density and magnetic field from the solar wind will strongly affect the dispersion and rotation measure of the pulsar. Here we present the effect from pulsar observations and describe our model of the solar wind.

Mildly recyled pulsars (MRP), conventionally defined as neutron star having spin period in the 20–100 ms range and surface magnetic field

We have applied a cross correlation analysis to timing observations of 20 pulsars to study the isotropic, stochastic gravitational‐wave background signal. No gravitational‐wave signal was detected. We showed that, because of the variable data spans and noise levels across the 20 time series, only a few pulsars contribute to estimating the gravitational‐wave signal. This prohibits the calculation of a 95% confidence upper bound on the amplitude of the gravitational‐wave background.

We present results of electron‐positron pair cascade simulations in a dipole magnetic field whose polar cap is offset from the dipole axis. In such a field geometry, the polar cap is displaced a small fraction of the neutron star radius from the star symmetry axis and the field line radius of curvature is modified. Using the modified parallel electric field near the offset polar cap, we simulate pair cascades to determine the pair deathlines and pair multiplicities as a function of the offset. We find that the pair multiplicity can change dramatically with a modest offset, with a significant increase on one side of the polar cap. Lower pair deathlines allow a larger fraction of the pulsar population, that include old and millisecond pulsars, to produce cascades with high multiplicity. The results have some important implications for pulsar particle production, high‐energy emission and cosmic‐ray contribution.

The 43m telescope at the NRAO site in Green Bank, WV has recently been outfitted with a clone of the Green Bank Ultimate Pulsar Processing Instrument (GUPPI \cite{Ransom:2009}) backend, making it very useful for a number of pulsar related studies in frequency ranges 800-1600 MHz and 220-440 MHz. Some of the recent science being done with it include: monitoring of the Crab pulsar, a blind search for transient sources, pulsar searches of targets of opportunity, and an all-sky mapping project. For the Crab monitoring project, regular observations are searched for giant pulses (GPs), which are then correlated with $\gamma$-ray photons from the \emph{Fermi} spacecraft. Data from the all-sky mapping project are first run through a pipeline that does a blind transient search, looking for single pulses over a DM range of 0-500 pc~cm$^{-3}$. These projects are made possible by MIT Lincoln Labs., Comment: 2 pages, 1 figure, to appear in AIP Conference Proceedings of Pulsar Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe", Sardinia, October 2010

We demonstrate that the high‐magnetic field pulsar J1119−6127 exhibits three different types of behaviour in the radio band. Trailing the “normal” profile peak there is an “intermittent” peak and these components are flanked by two additional components showing very erratic “RRAT‐like” emission. Both the intermittent and RRAT‐like events are extremely rare and are preceded by a large amplitude glitch in the spin‐down parameters. The post‐glitch spin‐down rate is smaller than the pre‐glitch rate, which is very unusual for the pulsar population as a whole, but is observed in the glitch recovery of a RRAT. If the abnormal radiative behaviour in PSR J1119−6127 is indeed glitch induced then there might exist a population of neutron stars which only become visible in the radio band for a short duration in the immediate aftermath of glitch activity. These neutron stars will be visible in the radio band as sources that only emit some clustered pulses every so many years.

Several models have been proposed for the description of anomalous X‐ray pulsars (AXPs) and soft gamma‐ray repeaters (SGRs). The most widely discussed is the magnetar model, which involves a neutron stars with a surface magnetic field of the order of 1014÷1015 G [1]. Some other models put forward to explain the observed peculiarities of AXPs and SGRs. There is currently no model that can satisfactorily describe all the observational properties of these objects. We develope the drift model. Here, we discuss the applicability of the magnetar model and consider the feasibility of the drift model.Several models have been proposed for the description of anomalous X‐ray pulsars (AXPs) and soft gamma‐ray repeaters (SGRs). The most widely discussed is the magnetar model, which involves a neutron stars with a surface magnetic field of the order of 1014÷1015 G [1]. Some other models put forward to explain the observed peculiarities of AXPs and SGRs. There is currently no model that can satisfactorily describe all the observational properties of these objects. We develope the drift model. Here, we discuss the applicability of the magnetar model and consider the feasibility of the drift model.

The High Time Resolution Universe survey for pulsars and fast transients has yielded the discovery of a slow radio pulsar, PSR J1622−4950, that despite its high dispersion measure exhibited a highly variable flux density and integrated pulse profile. The pulsar shares many properties with the two previously known magnetars that emit radio pulsations, including a similarly high inferred magnetic field strength. In contrast to other magnetars, PSR J1622−4950 shows no observed variations in X‐ray emission.

High‐precision pulsar timing relies on a solar system ephemeris in order to convert times of arrival (TOAs) of pulses measured at an observatory to the solar system barycenter. Any error in the conversion to the barycentric TOAs leads to a systematic variation in the observed timing residuals; specifically, an incorrect planetary mass leads to a predominantly sinusoidal variation having a period and phase associated with the planet’s orbital motion about the Sun. By using an array of pulsars (PSRs J0437−4715, J1744−1134, J1857+0943, J1909−3744), the masses of the planetary systems from Mercury to Saturn have been determined. These masses are consistent with the best‐known masses determined by spacecraft observations, with the mass of the Jovian system, 9.547921(2)×10−4M⊙, being significantly more accurate than the mass determined from the Pioneer and Voyager spacecraft, and consistent with but less accurate than the value from the Galileo spacecraft. While spacecraft are likely to produce the most accurat...

The results of radio emission observations from AXP 1E 2259+586 and 4U 0142+61 are reported. The observations were carried out on two sensitive transit radio telescopes at two frequencies 111 and 62 MHz. New data of pulse profiles and dynamic spectra are presented. Comparison with X‐ray data shows large differences in the mean pulse widths and the flux variations.

Millisecond pulsars are intrinsically very stable clocks and precise measurement of their observed pulse periods can be used to study a wide variety of astrophysical phenomena. In particular, observations of a large sample of millisecond pulsars at regular intervals, constituting a Pulsar Timing Array (PTA), can be used as a detector of low-frequency gravitational waves and to establish a standard of time independent of terrestrial atomic timescales. Three major timing array projects have been established: The European Pulsar Timing Array (EPTA), the North American pulsar timing array (NANOGrav) and the Parkes Pulsar Timing Array (PPTA). Results from the PPTA project are described in some detail and future prospects for PTA projects are discussed., Comment: 8 pages, 3 figures, to appear in the AIP Conference Proceedings for the Pulsar Conference 2010, Sardinia, Italy, October 2010

Fermi‐LAT and AGILE have already detected more than 70 rotation‐powered pulsars at GeV energies, opening a new era of pulsar physics. In particular, Fermi has unveiled the existence of a large population of Geminga‐like pulsars, γ‐ray bright but radio‐silent. We used XMM‐Newton, Chandra and Swift to study such new, γ‐ray selected, pulsar population and to compare its X‐ray behaviour with that of the radio pulsars. While radio‐loud and radio‐quiet pulsars need not to be different objects, their different viewing geometry with respect to the observer does influence the ratio between γ and X‐ray emissions. When plotting the distance‐indipendent γ to X‐ray flux ratios as a function of the pulsars’ rotational energy losses, one immediately sees that pulsars with similar energetics have Fγ/FX spanning 3 decades. Such spread, most probably stemming from vastly different geometrical configurations of the X and γ‐ray emitting regions, defies any straightforward interpretation of the plot. We find that, on average,...

The Double Pulsar (J0737‐3039) is an exceptional physical laboratory. It allows us to probe pulsar emission mechanisms, physical processes related to pulsars and General Relativity tests. In this poster we examine a mechanism where spin‐down is caused by the field lines which are open with respect to the magnetosphere. The orbital variation of the magnetosphere adds a periodic imprint to the derivative of the spin frequency of pulsar B which will be observed as a higher order correction on the phase. This modulation can be used to provide information for clearing the signal received from Pulsar B from the noise which is essential for high precision General Relativity tests. We also evaluate the magnetic field of Pulsar B and the shape of the boundary.

We consider the radiative transfer problem in a plane‐parallel slab of thermal electrons in presence of an ultra‐strong magnetic field (B≳4.4×1013 G). Under such conditions, the magnetic field behaves as a birefringent medium for the propagating photons, and the electromagnetic radiation is splitted into two polarization modes, ordinary and extraordinary, having different cross‐sections. When the optical depth of the slab is large, the ordinary‐mode photons are significantly more Comptonized and the photon field is dominated by the isotropic component. For sub‐relativistic electron temperatures, it is possible to treat the full kinetic Boltzmann equation for such photons using the Fokker‐Planck approximation. The full solution is then obtained by the method of variable separation. We report the numerical solution obtained for eigenvalues and eigenfunctions of the space operator, and consider the emerging Comptonization spectrum of the ordinary‐mode photons for energies significantly less than the cyclotro...

We investigate the unique nulling properties PSR B0818−41 with the GMRT at 325 and 610 MHz. A strong trend in the intensity fluctuations of the individual pulses just before and after the nulls is observed by us for this pulsar. In addition, we report a possible connection between the intensity fluctuations and the drift rate of subpulses just before and after the nulls. We find some very specific and well correlated changes in the radio emission properties of PSR B0818−41 when the emission restarts after a null. These could imply that the phenomenon of nulling is associated with some kind of a “reset” of the pulsar radio emission engine.