X-ray and gamma-ray upper limits for pulsed emission from radio pulsars

We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4−650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of ∼20.1 (3300–10500 Å). The optical emission was variable on timescales from hundreds to thousands of seconds. The spectrum showed prominent emission lines with variable profiles at different epochs. Simultaneous XMM-Newton and NuSTAR observations revealed a bimodal distribution of the X-ray count rates on timescales as short as tens of seconds, as well as sporadic flaring activity. The average broad-band (0.3–79 keV) spectrum was adequately described by an absorbed power law model with photon index of Γ = 1.63 ± 0.01 (at 1σ c.l.), and the X-ray luminosity was (2.16 ± 0.04) × 1034 erg s−1 for a distance of 4 kpc. Based on observations with different instruments, the X-ray luminosity has remained relatively steady over the past ∼15 years. J1109 is spatially associated with the gamma-ray source FL8Y J1109.8−6500, which was detected with Fermi at an average luminosity of (1.5 ± 0.2) × 1034 erg s−1 (assuming the distance of J1109) over the 0.1–300 GeV energy band between 2008 and 2016. The source was undetected during ATCA radio observations that were simultaneous with NuSTAR, down to a 3σ flux upper limit of 18 μJy beam−1 (at 7.25 GHz). We show that the phenomenological properties of J1109 point to a binary transitional pulsar candidate currently in a sub-luminous accretion disk state, and that the upper limits derived for the radio emission are consistent with the expected radio luminosity for accreting neutron stars at similar X-ray luminosities.

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Sigma upper limits to the hard X-ray/soft gamma-ray emission from the millisecond pulsars of the nearby globular cluster 47 Tucunae

The Astrophysical Journal ◽

10.1086/186765 ◽

1993 ◽

Vol 405 ◽

pp. L59 ◽

Cited By ~ 2

Author(s):

D. Barret ◽

P. Mandrou ◽

M. Denis ◽

J. F. Olive ◽

P. Laurent ◽

...

Keyword(s):

Globular Cluster ◽

Gamma Ray ◽

Millisecond Pulsars ◽

X Ray ◽

Upper Limits ◽

Gamma Ray Emission

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X-ray and Gamma-ray Observations of Pulsars

Symposium - International Astronomical Union ◽

10.1017/s0074180900092974 ◽

1981 ◽

Vol 95 ◽

pp. 241-250 ◽

Cited By ~ 2

Author(s):

R. Buccheri

Keyword(s):

Gamma Ray ◽

Theoretical Models ◽

Radio Pulsars ◽

X Ray ◽

Special Regard ◽

Energy Domain ◽

Similarities And Differences

Measurements of pulsars in the energy domain above ~ 1 keV have provided in the last few years new and interesting results. This paper presents a review of the observational features of PSR 0531+21 and PSR 0833–45 (the Crab and Vela pulsars). Searches for pulsed emission from old radio pulsars in the same energy domain are also reviewed and results assessed. The comparison of the observed features with each other and with the corresponding features observed at lower energies reveals similarities and differences capable to constrain theoretical models with special regard to the geometry of the emission mechanisms.

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Searching for X-ray counterparts of Fermi Gamma-ray pulsars in Suzaku observations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312013130 ◽

2011 ◽

Vol 7 (S279) ◽

pp. 317-318 ◽

Cited By ~ 1

Author(s):

Yu Aoki ◽

Takahiro Enomoto ◽

Yoichi Yatsu ◽

Nobuyuki Kawai ◽

Takeshi Nakamori ◽

...

Keyword(s):

Gamma Ray ◽

Thermal Emission ◽

Flux Ratio ◽

Radio Pulsars ◽

Pulsar Wind Nebulae ◽

X Ray ◽

Absorbed Power ◽

Pulsar Wind ◽

Error Circle

AbstractWe report the Suzaku follow-up observations of the Gamma-ray pulsars, 1FGL J0614,13328, J1044.55737, J1741.82101, and J1813.31246, which were discovered by the Fermi Gamma-ray observatory. Analysing Suzaku/XIS data, we detected X-ray counterparts of these pulsars in the Fermi error circle and interpreted their spectra with absorbed power-law functions. These results indicate that the origin of these X-ray sources is non-thermal emission from the pulsars or from Pulsar Wind Nebulae (PWNe) surrounding them. Moreover we found that J1741.82101 exhibits a peculiar profile: spin-down luminosity vs flux ratio between X- and gamma-rays is unusually large compared to usual radio pulsars.

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Emission of particles and photons in the pulsar polar cap

International Astronomical Union Colloquium ◽

10.1017/s0252921100060346 ◽

2000 ◽

Vol 177 ◽

pp. 473-478

Author(s):

A. I. Tsygan

Keyword(s):

Gamma Ray ◽

Radio Pulsars ◽

Polar Cap ◽

X Ray ◽

Polar Caps ◽

Electron Positron ◽

Inertial Frames ◽

General Relativistic ◽

Star Surface ◽

General Relativistic Effect

AbstractWe study emission of particles and photons from a pulsar polar cap. The Goldreich-Julian model for the regime of free emission of charged particles from the neutron star surface is used. In this case the electric field is generated due to the general relativistic effect of dragging of inertial frames. The spectra and shapes of gamma-ray pulses, the parameters of the electron-positron plasma and the intensity of X-ray emission from hot spots in the polar region of radio pulsars are discussed. The effect of non-dipole magnetic field on X-ray emission of polar caps is considered. It is shown that the increase of magnetic line curvature leads to much smaller temperatures and X-ray luminosities of the polar caps as compared with the purely dipole field.

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COS−B upper limits on gamma-ray emission from radio pulsars

10.1063/1.34083 ◽

1983 ◽

Author(s):

R. Buccheri

Keyword(s):

Gamma Ray ◽

Radio Pulsars ◽

Upper Limits ◽

Gamma Ray Emission

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Periodic Analysis of Gamma-Ray Data

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000022153 ◽

1987 ◽

Vol 7 (2) ◽

pp. 167-172 ◽

Cited By ~ 11

Author(s):

R. J. Protheroe

Keyword(s):

Gamma Ray ◽

Delta Function ◽

Confidence Bands ◽

Light Curves ◽

Periodic Signal ◽

X Ray ◽

Power Of Tests ◽

Upper Limits ◽

Periodic Analysis ◽

The Family

AbstractIn γ-ray astronomy one often wishes to search for a periodic signal from a suspected point source. Either one knows the period in advance, for example in the case of a radio pulsar, or at least a range of possible periods, or one has no information and is searching “blind”, as in the case of SN1987a, unidentified sources in the COS-B catalogue, or binary X-ray sources without known pulse periods. In both cases one should adopt a strategy which give the best chance of obtaining a statistically significant result. The power of tests using the family of statistics based on the Rayleigh statistic is discussed for two extreme forms of possible light curves: a uniform distribution plus a delta function, and a cartoid distribution. Strategies for using these statistics are discussed. Methods of obtaining confidence bands, and in the case of an unsuccessful search, upper-limits to any pulsed component are described, and graphs given which enable these to be calculated readily given the value of the statistic obtained.

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