Gamma Radiation from PSR B1055-52 (original) (raw)
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8 Gamma Radiation from PSR B1055−52
2016
The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055−52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics which distinguish this pulsar: the light curve is complex; there is no detectable unpulsed emission; the energy spectrum is flat, with no evidence of a sharp high-energy cutoff up to >4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.
Discovery of the Binary Pulsar PSR B1259-63 in VHE Gamma Rays
AIP Conference Proceedings, 2005
The detection of the binary system PSR B1259¦ 63 / SS 2883 with the High Energy Stereoscopic System (H.E.S.S.) of four imaging atmospheric Cherenkov telescopes is reported. PSR B1259¦ 63, a radio pulsar with a highly eccentric orbit around a very luminous, massive star was observed around its periastron passage in February/March 2004. Very high energy (VHE) gamma-ray emission has been predicted to be produced in the interaction region of the pulsar wind and the photon field of the star, where accelerated electrons are believed to undergo Inverse Compton scattering. The flux of the gamma-ray emission should then depend on the pulsar orbital phase. Gamma-ray signals with a significance § 10σ were detected above an energy threshold of 380 GeV. The measured flux varies significantly on timescales of days. The spectrum derived from the pre-periastron data has a flux level of 7% of the Crab Nebula flux and a photon index of Γ © 2 7 0 3 stat .
AGILE OBSERVATIONS OF THE "SOFT" GAMMA-RAY PULSAR PSR B1509-58
2010
We present the results of new AGILE observations of PSR B1509-58 performed over a period of ∼2.5 years following the detection obtained with a subset of the present data. The modulation significance of the lightcurve above 30 MeV is at a 5σ confidence level and the lightcurve is similar to those found earlier by COMPTEL up to 30 MeV: a broad asymmetric first peak reaching its maximum 0.39 ± 0.02 cycles after the radio peak plus a second peak at 0.94 ± 0.03. The gamma-ray spectral energy distribution of the pulsed flux detected by COMP-TEL and AGILE is well described by a power-law (photon index α = 1.87±0.09)
Gamma-ray pulsars: the Compton Observatory contribution to the study of isolated neutron stars
AIP Conference Proceedings
The four instruments on the Compton Gamma Ray Observatory have identi ed at least seven isolated neutron stars by their pulsed gamma-ray emission. For all of these, the gamma radiation represents the largest observable fraction of the spin-down luminosi ty, making the gamma rays important diagnostics of particle acceleration and interaction in the neutron star magnetospheres. Several other \candidate" pulsars have tentative identi cations based on pulsed radiation or positional association. The ense mble of CGRO pulsar detections, possible detections, and upper limits yields a number of patterns, most of which have exceptions. Some examples: (1) All except PSR B1509?58 have light curves consistent with double pulses; (2) All except the Crab have radio pulses out of phase with the gamma-ray pulses (the relative phase of the recently-reported radio pulse from Geminga is not known as of this w riting); (3) Except possibly for PSR B1509?58 and PSR B0656+14, the gamma-ray energy spectra atten with increasing pulsar age; (4) All except PSR B1951+32 show evidence of having high-energy spectral cuto s in the CGRO energy band; (5) The pulsed u x from all the pulsars is relatively constant with time; (6) There is a trend for the pulsar luminosity to increase with increasing polar-cap current (or open eld line voltage, or _ E, all of which are similar), although the candidate PSR B065 6+14 does not t well. The diversity in the phenomenology of gamma-ray pulsars presents challenges to pulsar models. For example, doublepole models, often invoked by radio astronomers, now seem problematic. Most models! have evolved signi cantly in response to the CGRO discoveries, and no comprehensive explanation for all the observations is yet in hand.
The Astrophysical Journal, 2010
The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057−5226, PSR J1709−4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from these pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.
PSR J1838–0537: Discovery of a Young, Energetic Gamma-Ray Pulsar
The Astrophysical Journal, 2012
We report the discovery of PSR J1838−0537, a gamma-ray pulsar found through a blind search of data from the Fermi Large Area Telescope (LAT). The pulsar has a spin frequency of 6.9 Hz and a frequency derivative of −2.2 × 10 −11 Hz s −1 , implying a young characteristic age of 4970 years and a large spin-down power of 5.9 × 10 36 erg s −1. Follow-up observations with radio telescopes detected no pulsations, thus PSR J1838−0537 appears radio-quiet as viewed from Earth. In September 2009 the pulsar suffered the largest glitch so far seen in any gamma-ray-only pulsar, causing a relative increase in spin frequency of about 5.5 × 10 −6. After the glitch, during a putative recovery period, the timing analysis is complicated by the sparsity of the LAT photon data, the weakness of the pulsations, and the reduction in average exposure from a coincidental, contemporaneous change in the LAT's sky-survey observing pattern. The pulsar's sky position is coincident with the spatially extended TeV source HESS J1841−055 detected by the High Energy Stereoscopic System (H.E.S.S.). The inferred energetics suggest that HESS J1841−055 contains a pulsar wind nebula powered by the pulsar.
Studies of high-energy pulsars: The special case of PSR J1849-0001
Nuclear and Particle Physics Proceedings, 2018
We present the results from the data analysis of the XMM-Newton observation (53.6 ks) on PSR J1849-0001. We studied in detail the X-ray emission of this pulsar and we found extended emission (up to ≈ 100 arcsec) from the Pulsar Wind Nebula (PWN), confirming that this is a case of a Pulsar/PWN system and strengthening the evidence that X-ray, hard X-ray and TeV gamma-ray sources are manifestations of the same system. Another important result of our study is the clear evidence that the X-ray PWN of PSR J1849-0001 is asymmetric.
GAMMA-RAY AND RADIO PROPERTIES OF SIX PULSARS DETECTED BY THE FERMI LARGE AREA TELESCOPE
The Astrophysical Journal, 2010
We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850 and J1718-3825 using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. The observed phases of the γ-ray light curves are, in general, consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. This allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models.
The Astrophysical Journal, 2009
We report the detection of γ-ray pulsations (≥ 0.1 GeV) from PSR J2229+6114 and PSR J1048−5832, the latter having been detected as a low-significance pulsar by EGRET. Data in the γ-ray band were acquired by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope, while the radio rotational ephemerides used to fold the γ-ray light curves were obtained using the Green Bank Telescope, the Lovell telescope at Jodrell Bank, and the Parkes telescope. The two young radio pulsars, located within the error circles of the previously unidentified EGRET sources 3EG J1048−5840 and 3EG J2227+6122, present spin-down characteristics similar to the Vela pulsar. PSR J1048−5832 shows two sharp peaks at phases 0.15 ± 0.01 and 0.57 ± 0.01 relative to the radio pulse confirming the EGRET light curve, while PSR J2229+6114 presents a very broad peak at phase 0.49 ± 0.01. The γ-ray spectra above 0.1 GeV of both pulsars are fit with power laws having exponential cutoffs near 3 GeV, leading to integral photon fluxes of (2.19 ± 0.22 ± 0.32) × 10 −7 cm −2 s −1 for PSR J1048−5832 and (3.77 ± 0.22 ± 0.44) × 10 −7 cm −2 s −1 for PSR J2229+6114. The first uncertainty is statistical and the second is systematic. PSR J1048−5832 is one of two LAT sources which were entangled together as 3EG J1048−5840. These detections add to the growing number of young γ-ray pulsars that make up the dominant population of GeV γ-ray sources in the Galactic plane.