Observations of the γ-ray pulsar J1932+1916 in X-rays

AbstractSuper-hard γ-ray radiation spectra have been calculated. This radiation is generated near the velocity-of-light cylinder through the process of inverse-Compton scattering of relativistic electrons by thermal photons radiated by a neutron star. These calculations have been compared with observations of the Crab and Vela pulsars at 1000-GeV γ-ray energies. A correlation between γ-ray flares and those in soft (Ex ≃ lkeV) X-rays are predicted.

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The Flare of 1989 September 9, 09:09 UT: Does Coronal Loop Collision Initiate Efficient Gamma-Ray Emission?

International Astronomical Union Colloquium ◽

10.1017/s0252921100078003 ◽

1994 ◽

Vol 142 ◽

pp. 707-711

Author(s):

H. Aurass ◽

A. Hofmann ◽

E. Rieger

Keyword(s):

Current Sheet ◽

Gamma Rays ◽

Coronal Loop ◽

Gamma Ray ◽

High Energy ◽

X Rays ◽

Subject Headings ◽

Γ Ray ◽

Gamma Ray Emission ◽

Magnetogram Data

AbstractVector magnetogram data and Hα pictures together with data published by Chupp et al. lead us to conjecture that in the presented case a contact between the rising two-ribbon flare current sheet and a coronal loop connecting two nearby plage regions initiates efficient high-energy γ-ray emission.Subject headings: Sun: corona — Sun: flares — Sun: X-rays, gamma rays

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Gamma-ray-emitting narrow-line Seyfert 1 galaxies: the Swift view

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1580 ◽

2020 ◽

Vol 496 (2) ◽

pp. 2213-2229 ◽

Cited By ~ 1

Author(s):

F D’Ammando

Keyword(s):

Gamma Ray ◽

Thermal Emission ◽

Optical Emission ◽

X Rays ◽

Narrow Line ◽

X Ray ◽

Relativistic Jet ◽

Photon Index ◽

Γ Ray ◽

Lower Variability

ABSTRACT We report the analysis of all Swift observations available up to 2019 April of γ-ray-emitting narrow-line Seyfert 1 galaxies (NLSy1). The distribution of X-ray luminosities (and fluxes) indicates that the jet radiation significantly contributes to their X-ray emission, with Doppler boosting making values higher than other radio-loud NLSy1. The 0.3–10 keV photon indices are on average harder with respect to radio-quiet and radio-loud NLSy1, confirming a dominant jet contribution in X-rays. However, the lower variability amplitude with respect to blazars and the softening of the spectrum in some periods suggests that also the corona radiation contributes to the X-ray emission. In optical and ultraviolet (UV) significant flux changes have been observed on daily, weekly, and monthly time-scale, providing a clear indication of the significant contribution of the jet radiation in this part of spectrum. A strong correlation between X-ray, UV, and optical emission and simultaneous flux variations have been observed in 1H 0323+342, SBS 0846+513, PMN J0948+0022 as expected in case the jet radiation is the dominant mechanism. Correlated multiband variability favours the jet-dominated scenario also in FBQS J1644+2619 and PKS 2004−447. The summed X-ray Telescope spectra of 1H 0323+342, SBS 0846+513, PMN J0948+0022, and FBQS J1644+2619 are well fitted by a broken power law with a break around 2 keV. The spectrum above 2 keV is dominated by the non-thermal emission from a beamed relativistic jet, as suggested by the hard photon index. A Seyfert-like feature like the soft X-ray excess has been observed below 2 keV, making these γ-ray-emitting NLSy1 different from typical blazars.

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A New Chapter in Hard X-rays of the M87 AGN

Proceedings ◽

10.3390/proceedings2019017009 ◽

2019 ◽

Vol 17 (1) ◽

pp. 9

Author(s):

Ka-Wah Wong ◽

Rodrigo S. Nemmen ◽

Jimmy A. Irwin ◽

Dacheng Lin

Keyword(s):

High Energy ◽

X Rays ◽

X Ray ◽

Accretion Flow ◽

Relativistic Jet ◽

Very High Energy ◽

Γ Ray ◽

High Energy Emission ◽

First Time ◽

Very High

The nearby M87 hosts an exceptional relativistic jet. It has been regularly monitored in radio to TeV bands, but little has been done in hard X-rays ≳10 keV. For the first time, we have successfully detected hard X-rays up to 40 keV from its X-ray core with joint Chandra and NuSTAR observations, providing important insights to the X-ray origins: from the unresolved jet or the accretion flow. We found that the hard X-ray emission is significantly lower than that predicted by synchrotron self-Compton models introduced to explain very-high-energy γ -ray emission above a GeV. We discuss recent models to understand these high energy emission processes.

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A NuSTAR view of powerful γ-ray loud blazars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935750 ◽

2019 ◽

Vol 627 ◽

pp. A72 ◽

Cited By ~ 2

Author(s):

G. Ghisellini ◽

M. Perri ◽

L. Costamante ◽

G. Tagliaferri ◽

T. Sbarrato ◽

...

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Peak Frequency ◽

High Energy ◽

Spectral Energy ◽

X Rays ◽

X Ray ◽

Γ Ray ◽

The Universe ◽

Jet Power

We observed three blazars at z > 2 with the NuSTAR satellite. These were detected in the γ-rays by Fermi/LAT and in the soft X-rays, but have not yet been observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to estimate their total electromagnetic output and peak frequency. For some of them we were able to study the source in different states, and investigate the main cause of the different observed spectral energy distribution. We then collected all blazars at redshifts greater than 2 observed by NuSTAR, and confirm that these hard and luminous X-ray blazars are among the most powerful persistent sources in the Universe. We confirm the relation between the jet power and the disk luminosity, extending it at the high-energy end.

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Semi-Insulating InP Particle Detectors For X- And γ-Ray Detection

MRS Proceedings ◽

10.1557/proc-487-477 ◽

1997 ◽

Vol 487 ◽

Cited By ~ 5

Author(s):

P. G. Pelfer ◽

F. Dubecký ◽

R. Fomari ◽

M. Pikna ◽

M. Krempaský ◽

...

Keyword(s):

Electrical Properties ◽

Energy Resolution ◽

Collection Efficiency ◽

Charge Collection ◽

Back Contact ◽

X Rays ◽

Particle Detectors ◽

Charge Collection Efficiency ◽

Γ Ray ◽

Α Particles

AbstractA study of electrical properties and detection performances of the semi-insulating (SI) InP based detectors is presented. Detectors with a top P+ layer and a Schottky back contact give the charge collection efficiency about 90 % and an energy resolution 3.7% (FWHM) for 5.48MeV α-particles at 250 K. Detection of X-rays (122 keV and 60 keV) photons in temperature region 220–250 K is demonstrated. Multiple peaking observed during detection of photons is discussed.

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A time-luminosity correlation for γ-ray bursts in the X-rays

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1111/j.1745-3933.2008.00560.x ◽

2008 ◽

Vol 391 (1) ◽

pp. L79-L83 ◽

Cited By ~ 96

Author(s):

M. G. Dainotti ◽

V. F. Cardone ◽

S. Capozziello

Keyword(s):

X Rays ◽

Γ Ray

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Middle aged γ-ray pulsar J1957+5033 in X-rays: pulsations, thermal emission and nebula

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3991 ◽

2020 ◽

Author(s):

D A Zyuzin ◽

A V Karpova ◽

Y A Shibanov ◽

A Y Potekhin ◽

V F Suleimanov

Keyword(s):

Neutron Star ◽

Neutron Stars ◽

Power Law ◽

Thermal Emission ◽

Single Pulse ◽

X Rays ◽

Middle Aged ◽

X Ray ◽

Photon Index ◽

Γ Ray

Abstract We analyze new XMM-Newton and archival Chandra observations of the middle-aged γ-ray radio-quiet pulsar J1957+5033. We detect, for the first time, X-ray pulsations with the pulsar spin period of the point-like source coinciding by position with the pulsar. This confirms the pulsar nature of the source. In the 0.15–0.5 keV band, there is a single pulse per period and the pulsed fraction is ≈18 ± 6 per cent. In this band, the pulsar spectrum is dominated by a thermal emission component that likely comes from the entire surface of the neutron star, while at higher energies (≳ 0.7 keV) it is described by a power law with the photon index Γ ≈ 1.6. We construct new hydrogen atmosphere models for neutron stars with dipole magnetic fields and non-uniform surface temperature distributions with relatively low effective temperatures. We use them in the spectral analysis and derive the pulsar average effective temperature of ≈(2 − 3) × 105 K. This makes J1957+5033 the coldest among all known thermally emitting neutron stars with ages below 1 Myr. Using the interstellar extinction–distance relation, we constrain the distance to the pulsar in the range of 0.1–1 kpc. We compare the obtained X-ray thermal luminosity with those for other neutron stars and various neutron star cooling models and set some constraints on latter. We observe a faint trail-like feature, elongated ∼8 arcmin from J1957+5033. Its spectrum can be described by a power law with a photon index Γ = 1.9 ± 0.5 suggesting that it is likely a pulsar wind nebula powered by J1957+5033.

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A radio-fluorogenic polymer-gel makes fixed fluorescent images of complex radiation fields

10.20944/preprints201806.0238.v1 ◽

2018 ◽

Author(s):

John Warman ◽

Matthijs deHaas ◽

Leonard Luthjens ◽

Antonia Denkova ◽

Tiantian Yao

Keyword(s):

Radioactive Isotope ◽

Three Dimensional ◽

Organic Polymer ◽

X Rays ◽

Polymer Gel ◽

Tertiary Butyl ◽

Pyrene Fluorescence ◽

Radiation Fields ◽

Radiation Induced ◽

Γ Ray

Abstract: We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g. maleimido-pyrene (MPy). The radio-fluorogenic effect depends on copolymerization of the MPy into growing chains of TBA on radiation-induced polymerization. This converts the maleimido residue, which quenches the pyrene fluorescence, into a succinimido moeity (SPy), which doesn't. The intensity of the fluorescence is proportional to the yield of free-radicals formed and hence to the local dose deposited. Because the SPy moieties are built into the cross-linked polymer matrix the image is fixed. The method of preparing the gel and imaging the radiation-induced fluorescence are presented and discussed. The effect is illustrated with fluorescent images of the energy deposited in the gel by beams of X-rays, electrons and protons as well as a radioactive isotope.

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Theories of discrete X-ray and γ-ray sources: (Invited discourse)

Symposium - International Astronomical Union ◽

10.1017/s0074180900004332 ◽

1970 ◽

Vol 37 ◽

pp. 216-237

Author(s):

James E. Felten

Keyword(s):

Synchrotron Radiation ◽

Supernova Remnants ◽

Galactic Plane ◽

Theoretical Work ◽

X Rays ◽

X Ray ◽

Γ Ray ◽

Low Efficiency ◽

Optical Flux ◽

Galactic Sources

This is a critical review of theories of known discrete X-ray sources. The Crab is omitted, having been dealt with in Woltjer's review. Two of the identified sources, Sco X-1 and Cyg X-2, seem to be of the same sort. A binary or gas-stream model like that of Prendergast and Burbidge, with dimension R ∼ 109 cm and density n ∼ 1016 cm−3, appears reconcilable with the observed features of these sources, though much detailed work remains to be done. Neither object is yet known to be binary. Theoretical work becomes more difficult if, as appears to be the case at least for Sco X-1, the objects are optically thick due to electron scattering; this may affect the optical and X-ray spectra.The recent searches for iron lines in the X-ray spectrum of Sco X-1 are reviewed briefly. The calculations and the energy resolution are not yet good enough to make this a dependable test of models.Several possibilities are offered for explaining the excess radio flux from Sco X-1.Other theories of Sco X-1-type sources are discussed briefly. The theory of Manley and Olbert seems a little superfluous when the gas-stream theory is still in a strong position.There are serious discrepancies between X-ray and optical estimates of the distance to Sco X-1. 21-cm measurements must also be considered. The situation is reviewed, and ways out of the difficulty are discussed.Cen X-2 seems to be like Sco X-1, but several other unidentified sources have hard spectra like the Crab. It is tempting to speculate that most of the galactic sources are supernova remnants.The extended γ-ray source in the galactic plane may be the extrapolated unresolved sum of galactic X-ray sources, as suggested by Ogelman. There are several other possibilities.M87 is the only established extragalactic source. Radio, optical and X-ray observations are summarized and graphed. A power-law extrapolation to the X-ray band is far from mandatory; nevertheless the optical flux from the jet is known to be synchrotron radiation. The time-scale difficulties in the jet are described, and several theories of the survival of the optical electrons are reviewed.Processes for producing X-rays other than thermal bremsstrahlung and synchrotron radiation are listed. These other processes are characterized by low efficiency, and are likely to be unimportant in discrete sources, though several have attracted attention with reference to the diffuse background.

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