Upper limits to soft gamma-ray flux from seven X-ray sources and from the galactic plane

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

The Astrophysical Journal ◽

10.1086/160276 ◽

1982 ◽

Vol 260 ◽

pp. 553 ◽

Cited By ~ 11

Author(s):

F. K. Knight ◽

J. L. Matteson ◽

L. E. Peterson ◽

R. E. Rothschild

Keyword(s):

Gamma Ray ◽

Radio Pulsars ◽

X Ray ◽

Upper Limits

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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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Interstellar Matter in Globular Clusters

Symposium - International Astronomical Union ◽

10.1017/s0074180900042637 ◽

1988 ◽

Vol 126 ◽

pp. 411-422

Author(s):

Morton S. Roberts

Keyword(s):

Mass Loss ◽

Globular Clusters ◽

Galactic Plane ◽

Interstellar Matter ◽

Sherlock Holmes ◽

Night Time ◽

X Ray ◽

Upper Limits ◽

Intracluster Matter

“Is there any point to which you would wish to draw my attention?”“To the curious incident of the dog in the night-time.”“The dog did nothing in the night-time.”“That was the curious incident,” remarked Sherlock Holmes.Memoirs of Sherlock HolmesThe source for intracluster matter is seen in various mass loss processes ongoing within clusters and is supported by the theoretical need for mass loss to explain the morphology of cluster colormagnitude diagrams. A variety of techniques ranging from X-ray to radio wavelengths have been employed to search for such matter but with few exceptions has not been found. The amount of material expected to collect between cleansing passages through the galactic plane has variously been estimated at between ∼ 102 and ∼ 103 M⊙. In contrast, observed upper limits for many clusters are well below these values, often > 1 M⊙. The few detections are at levels of ≲10−2 M⊙.

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The population of TeV pulsar wind nebulae in the H.E.S.S. Galactic Plane Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201629377 ◽

2018 ◽

Vol 612 ◽

pp. A2 ◽

Cited By ~ 48

Author(s):

◽

H. Abdalla ◽

A. Abramowski ◽

F. Aharonian ◽

F. Ait Benkhali ◽

...

Keyword(s):

Gamma Ray ◽

Galactic Plane ◽

High Energy ◽

Pulsar Wind Nebulae ◽

Upper Limits ◽

Very High Energy ◽

Consistent Picture ◽

Pulsar Wind ◽

Asymmetric Environment ◽

First Time

The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of TeV pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spin-down power Ė. This seems to be caused both by an increase of extension with decreasing Ė, and hence with time, compatible with a power law RPWN(Ė) ~Ė−0.65±0.20, and by a mild decrease of TeV gamma-ray luminosity with decreasing Ė, compatible with L1−10 TeV ~Ė0.59±0.21. We also find that the offsets of pulsars with respect to the wind nebula centre with ages around 10 kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar offset is correlated with a high apparent TeV efficiency L1−10 TeV∕Ė. In addition to 14 HGPS sources considered firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that are likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.

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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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