Gamma‐Ray Emission Properties from Mature Pulsars in the Galaxy and in the Gould Belt

Cheng, K. S.; Zhang, L.; Leung, P.; Jiang, Zewen

doi:10.1086/386537

Cited by 19 publications

(29 citation statements)

References 43 publications

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“…However, since their simulation accounts for only $1/4 of the total unidentified -ray population, the hypothesis that all of the sources are pulsars would suggest that $15 radio-loud pulsars ought to have been detectable in our sample of EGRET sources. A similar study by Cheng et al (2004), based on the outer gap emission model, finds $4 radio-loud pulsars from the Gould Belt and another four from the remainder of the Galaxy at jbj > 5 . The total number of pulsars at midlatitudes from this simulation accounts for $1/2 the total unidentified population, indicating that our survey should have detected $8 associated radio pulsars.…”

Section: Discussionmentioning

confidence: 69%

“…This luminosity limit is lower than the 1400 MHz luminosity of all but two pulsars for which this quantity has been measured and published (Manchester et al 2005). 12 The surveys used for the studies mentioned above were typically $4 times less sensitive than our survey (assuming an average spectral index of À2 for pulsars, as was assumed by Cheng et al 2004). Our results suggest that the simulations significantly overestimate the radio-loud -ray pulsar population at midlatitudes and do not support the hypothesis that middle-aged, nearby pulsars make up the majority of the unidentified sources.…”

Section: Discussionmentioning

confidence: 72%

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A Survey of 56 Midlatitude EGRET Error Boxes for Radio Pulsars

Crawford

Roberts

Hessels

et al. 2006

ApJ

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We have conducted a radio pulsar survey of 56 unidentified -ray sources from the third EGRET catalog that are at intermediate Galactic latitudes (5 < jbj < 73 ). For each source, four interleaved 35 minute pointings were made with the 13 beam, 1400 MHz multibeam receiver on the Parkes 64 m radio telescope. This covered the 95% error box of each source at a limiting sensitivity of $0.2 mJy to pulsed radio emission for periods P k 10 ms and dispersion measures P50 pc cm À3. Roughly half of the unidentified -ray sources at jbj > 5 with no proposed active galactic nucleus counterpart were covered in this survey. We detected nine isolated pulsars and four recycled binary pulsars, with three from each class being new discoveries. Timing observations suggest that only one of the pulsars has a spin-down luminosity that is even marginally consistent with the inferred luminosity of its coincident EGRET source. Our results suggest that population models, which include the Gould Belt as a component, overestimate the number of isolated pulsars among the midlatitude Galactic -ray sources, and that it is unlikely that Gould Belt pulsars make up the majority of these sources. However, the possibility of steep pulsar radio spectra and the confusion of terrestrial radio interference with long-period pulsars (P k 200 ms) having very low dispersion measures (P10 pc cm À3, expected for sources at a distance of less than about 1 kpc) prevent us from strongly ruling out this hypothesis. Our results also do not support the hypothesis that millisecond pulsars make up the majority of these sources. Nonpulsar source classes should therefore be further investigated as possible counterparts to the unidentified EGRET sources at intermediate Galactic latitudes.

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Section: Discussionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 72%

A Survey of 56 Midlatitude EGRET Error Boxes for Radio Pulsars

Crawford

Roberts

Hessels

et al. 2006

ApJ

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“…The basic procedure of the Monte Carlo method and the evolution of pulsar parameters are described in our previous works Zhang & Cheng 1999;Zhang et al 2000Zhang et al , 2004Cheng et al 2004). We have made two improvements in our Monte Carlo simulation: (i) Parkes 70 cm survey and Princeton NRAO survey data are used and (ii) the distance model of Cordes & Lazio (2002) is used to estimate the dispersion measure of the simulated pulsars.…”

Section: Monte Carlo Simulation Of γ-Ray Pulsarsmentioning

confidence: 99%

“…Based on the polar cap models, Harding & Zhang (2001) suggested that the off-beam γ-rays come from high-altitude curvature emission of primary particles and can radiate over a large solid angle and have a much softer spectrum than those of the main beams, and at least some of radio-quiet Gould belt sources detected by EGRET could be such off-beam γ-ray pulsars. In the framework of the outer gap model, Cheng et al (2004) investigated the emission properties of γ-ray pulsars in Galaxy and in the Gould belt.…”

Section: Introductionmentioning

confidence: 99%

Gamma-ray luminosity properties of gamma-ray pulsars

Zhang

Han

Jiang

2004

A&A

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Abstract. Based on a new self-consistent outer gap model, we statistically study luminosity properties of γ-ray pulsars with ages of ≤2 × 10 7 yr in the Galaxy as well as those with ages of ≤5 × 10 6 yr in the Gould belt using a Monte Carlo method, where the γ-ray beaming effect has been included. Generally, the relation between γ-ray luminosity, L γ , and pulsar spin-down power,, where δ is a parameter that depends on the galactic latitude and the γ-ray threshold. For a given γ-ray threshold (for example, the EGRET threshold or GLAST threshold), the parameter δ is an increasing function of the galactic latitude. For the EGRET threshold, δ changes smoothly with the galactic latitude. For the GLAST threshold, however, δ has a minimum at |b| ≤ 5• , and δ increases by a factor of ∼2 at the range of |b| = 5 • −10 • relative to δ at |b| ≤ 5• , and then increases smoothly as the galactic latitude further increases. The reason for this is that high galactic latitude γ-ray pulsars are dominated by mature pulsars. In fact, the ratio of γ-ray pulsars with their ages of >10 6 yr to all simulated γ-ray pulsars also increases with the galactic latitude. For the γ-ray pulsars produced in a fixed range of galactic latitude, the parameter δ increases slightly with the sensitivity of γ-ray detector.

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“…The thresholds of EGRET and GLAST included in Fig. 3 were taken from Cheng et al (2004) and McEnery et al (2004). With the high sensitivity of GLAST, which will be launched at the end of 2007, we should be able to detect the increase in gamma-ray flux.…”

Section: Discussionmentioning

confidence: 99%

Transient X-ray emission from normal galactic nuclei

Wong

Huang

Cheng

2007

A&A

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X-ray transients appearing in optically non-active galactic nuclei have been observed in recent years. The most popular model explaining this kind of phenomena is the conventional tidal disruption model. In this model, when a star moves within the tidal radius of a black hole, part of the star materials will fall into the black hole through an accretion disk, which gives rise to the luminous flare. We propose that the X-ray emission may not necessarily come from radiation of the accretion disk alone. Instead, it may be related to a jet. As the jet travels in the interstellar medium, a shock is produced and synchrotron radiation is expected. We compared the model light curve and the synchrotron radiation spectrum with the observed data and find that our model explains the observed light curve and late-time spectrum well. Our model predicts that these transient active galactic nuclei could be sources for study by the future gamma-ray satellites, e.g. GLAST, and the emission region will be expanding with time.

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Gamma‐Ray Emission Properties from Mature Pulsars in the Galaxy and in the Gould Belt

Cited by 19 publications

References 43 publications

A Survey of 56 Midlatitude EGRET Error Boxes for Radio Pulsars

A Survey of 56 Midlatitude EGRET Error Boxes for Radio Pulsars

Gamma-ray luminosity properties of gamma-ray pulsars

Transient X-ray emission from normal galactic nuclei

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