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We examined a model of partially screened gap region above the polar cap, in which the electron-positron plasma generated by sparking discharges coexists with thermionic flow ejected by the bombardment of the surface beneath these sparks.…

Astrophysics · Physics 2009-11-11 Janusz Gil , George Melikidze , Bing Zhang

Thermal radiation from hot polar caps is examined in radio pulsars with drifting subpulses. It is argued that if these subpulses correspond to sparking discharges of the inner acceleration region right above the polar cap surface then a…

Astrophysics · Physics 2007-05-23 Janusz Gil , George Melikidze , Bing Zhang

The subpulse drifting phenomenon in pulsar radio emission is considered within the partially screened inner gap model, in which the sub-Goldreich-Julian thermionic flow of iron ions or electrons coexists with the spark-associated…

Astrophysics · Physics 2008-11-26 Janusz Gil , George Melikidze , Bing Zhang

Despite the fact that pulsars have been observed for almost half a century, many questions have remained unanswered. We use the analysis of X-ray observations in order to study the polar cap region of radio pulsars. The size of the hot…

High Energy Astrophysical Phenomena · Physics 2013-04-19 Andrzej Szary

Radio pulsar subpulse drifting has been interpreted as rotation of sub-beams (sparks) of pair plasma produced by intermittent breakdowns of an inner vacuum gap above the pulsar polar cap. This model also predicts strong thermal X-ray…

Astrophysics · Physics 2007-05-23 Bing Zhang , Divas Sanwal , George G. Pavlov

The classical vacuum gap model of Ruderman & Sutherland, in which spark-associated subbeams of subpulse emission circulate around the magnetic axis due to the EB drift, provides a natural and plausible physical mechanism of the subpulse…

Astrophysics · Physics 2009-11-07 Janusz Gil , George I. Melikidze , Ulrich Geppert

We present the timing and spectral analyses of theXMM-newton data on the 17-Myr-old, nearby radio pulsar B0950+08. This observation revealed pulsations of the X-ray flux of the pulsar at its radio period. The pulse shape and pulsed fraction…

Astrophysics · Physics 2009-11-10 V. E. Zavlin , G. G. Pavlov

Observations of the thermal X-ray emission from old radio pulsars implicate that the size of hot spots is much smaller then the size of the polar cap that follows from the purely dipolar geometry of pulsar magnetic field. Plausible…

High Energy Astrophysical Phenomena · Physics 2012-07-20 Andrzej Szary , George Melikidze , Janusz Gil

We report the X-ray observations of two radio pulsars with drifting subpulses: B0834 + 06 and B0826 - 34 using \xmm\. PSR B0834 + 06 was detected with a total of 70 counts from the three EPIC instruments over 50 ks exposure time. Its…

Astrophysics · Physics 2009-11-13 J. Gil , F. Haberl , G. Melikidze , U. Geppert , B. Zhang , G. Melikidze

The origin and radiation mechanisms of high energy emissions from pulsars have remained mysterious since their discovery. Here we report, based on a sample of 68 pulsars, observational connection of non-thermal X-ray emissions from pulsars…

High Energy Astrophysical Phenomena · Physics 2023-02-15 Hsiang-Kuang Chang , Jr-Yue Hsiang , Che-Yen Chu , Yun-Hsin Chung , Tze-Hsiang Su , Tzu-Hsuan Lin , Chien-You Huang

The study of pulsars in the three and a half decades since their discovery has highlighted a handful of issues critical to their understanding. To date there is no consensus on the physical mechanism for their radio radio emission, despite…

Astrophysics · Physics 2009-11-10 Matthew G. Baring

The fastest millisecond pulsar PSR B1937+21 presents an interpulse separated from the main pulse by nealy 180^o at radio frequencies. Recently, the ASCA observations (Takahashi et al. 2001) detected pulsed X-ray emission from this pulsar.…

Astrophysics · Physics 2009-11-07 H. G. Wang , R. X. Xu , G. J. Qiao

We modify the conventional curvature radiation (inverse Compton scattering) + synchrotron radiation polar cap cascade model by including the inverse Compton scattering of the higher generation pairs. Within the framework of the…

Astrophysics · Physics 2009-10-31 Bing Zhang , Alice K. Harding

We show that the soft X-ray spectra and light curves observed with the ROSAT and EUVE from the closest known millisecond pulsar J0437--4715 can be interpreted as thermal radiation from two hot polar caps whose emitting layers (atmospheres)…

Astrophysics · Physics 2008-02-03 V. E. Zavlin , G. G Pavlov

We have completed part of a program to study the X-ray emission properties of old rotation-powered pulsars with XMM-Newton in order to probe and identify the origin of their X-radiation. The X-ray emission from these old pulsars is largely…

The analysis of X-ray observations suggest an ultrastrong ($B\gtrsim 10^{14} \,{\rm G}$) surface magnetic field at the polar cap of pulsars (Szary, 2013). On the other hand, the temperature of the polar caps is about a few millions Kelvin.…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Andrzej Szary , George Melikidze , Janusz Gil

I present an analysis of the XMM-Newton observations of four millisecond pulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The new data provide strong evidence of thermal emission in the X-ray flux detected from the first three…

Astrophysics · Physics 2010-11-11 Vyacheslav E. Zavlin

Coherent radio emission in pulsars is excited due to instabilities in a relativistically streaming non-stationary plasma flow, which is generated from sparking discharges in the inner acceleration region (IAR) near the stellar surface. A…

High Energy Astrophysical Phenomena · Physics 2020-06-10 Rahul Basu , Dipanjan Mitra , George I. Melikidze

The radio-quiet pulsar PSR J2021+4026 is mostly known because it is the only rotation-powered pulsar that shows variability in its {\gamma}-ray emission. Using XMM-Newton archival data, we first confirmed that its flux is steady in the…

High Energy Astrophysical Phenomena · Physics 2021-02-17 Michela Rigoselli , Sandro Mereghetti , Roberto Taverna , Roberto Turolla , Davide De Grandis

For polar-cap models based on electromagnetic cascades induced by curvature radiation of beam particles we calculate broad-band high-energy spe ctra of pulsed emission expected for classical ($\sim 10^{12}\G$) and millisecond pulsars ($\sim…

Astrophysics · Physics 2007-05-23 Bronislaw Rudak , Jaroslaw Dyks
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