Prolonged sub-luminous state of the new transitional pulsar candidate CXOU J110926.4−650224

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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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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Exceptionally bright optical emission from a rare and distant gamma-ray burst

10.21203/rs.3.rs-1101440/v1 ◽

2021 ◽

Author(s):

Gor Oganesyan ◽

Sergey Karpov ◽

Martin Jelinek ◽

Gregory Beskin ◽

Samuele Ronchini ◽

...

Keyword(s):

Gamma Ray ◽

Massive Stars ◽

Optical Emission ◽

Gamma Ray Bursts ◽

Additional Component ◽

Relativistic Jets ◽

X Ray ◽

Forward Shock ◽

Multi Wavelength ◽

Wavelength Emission

Abstract Long gamma-ray bursts (GRBs) are produced by the dissipation of ultra-relativistic jets launched by newly-born black holes after the collapse of massive stars. Right after the luminous and highly variable gamma-ray emission, the multi-wavelength afterglow is released by the external dissipation of the jet in circumburst medium. We report the discovery of a very bright (10 mag) optical emission 28 s after the explosion of the extremely luminous and energetic GRB 210619B located at redshift 1.937. Early multi-filter observations allowed us to witness the end of the shock wave propagation into the GRB ejecta. We observed the spectral transition from a bright reverse to the forward shock emission, demonstrating that the early and late GRB multi-wavelength emission is originated from a very narrow jet propagating into an unusually rarefied interstellar medium. We also find evidence of an additional component of radiation, coming from the jet wings which is able explain the uncorrelated optical/X-ray emission.

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Multi-wavelength Behaviour of III Zw2

Publications of the Astronomical Society of Australia ◽

10.1071/as01093 ◽

2002 ◽

Vol 19 (1) ◽

pp. 73-76

Author(s):

Nikita Salvi ◽

Mat J. Page ◽

Jason A. Stevens ◽

Keith O. Mason ◽

Kinwah Wu

Keyword(s):

Synchrotron Radiation ◽

Optical Emission ◽

High Energy ◽

X Rays ◽

X Ray ◽

High Energy Electrons ◽

Photon Index ◽

Multi Wavelength ◽

Wavelength Light ◽

Gaussian Line

AbstractIII Zw2 was observed with XMM-Newton in July 2000. Its X-ray spectrum can be described by a power law of photon index Γ≈1.7 with a Gaussian line at 6.7 KeV. There is no significant evidence of intrinsic absorption within the source or of a soft X-ray excess. Multi-wavelength light curves over a period of 25 years show related variations from the radio to X-rays. We interpret the radio to optical emission as synchrotron radiation, self-absorbed in the radio/millimetre region, and the X-rays as mainly due to Compton up-scattering of low energy photons by the population of high energy electrons that give rise to the synchrotron radiation.

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Superluminal Motion in the Gamma-Ray Blazar 3C 279

International Astronomical Union Colloquium ◽

10.1017/s0252921100044572 ◽

1998 ◽

Vol 164 ◽

pp. 69-70 ◽

Cited By ~ 6

Author(s):

S.C. Unwin ◽

A.E. Wehrle ◽

W. Xu ◽

A.C. Zook ◽

A.P. Marscher

Keyword(s):

Gamma Ray ◽

Spectral Energy Distribution ◽

Broad Band ◽

Spectral Energy ◽

Radio Sources ◽

X Ray ◽

Relativistic Jet ◽

Superluminal Motion ◽

Multi Wavelength ◽

Wavelength Monitoring

AbstractThe blazar 3C 279 is one of the strongest extragalactic sources of γ-rays, and is also one of the best studied superluminal radio sources. Definitive testing of models of the broad-band spectral energy distribution, especially in the X-ray and γ-ray regions requires knowledge of the evolution of the spectrum with time. Within the context of the relativistic jet model, multi-wavelength monitoring of the parsec-scale radio jet is also required. We present here the first steps toward such a test, using extensive VLBI monitoring over a 13 year interval at 22 GHz, and γ-ray observations between 1991 and 1996.

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Magnetar X-ray emission mechanisms

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312023484 ◽

2012 ◽

Vol 8 (S291) ◽

pp. 160-160

Author(s):

Silvia Zane

Keyword(s):

Spectral Analysis ◽

Physical Interpretation ◽

Spectral Properties ◽

Gamma Ray ◽

X Ray ◽

Spectral Components ◽

Self Consistent ◽

Photon Index ◽

Index 2 ◽

Surface Fields

AbstractSoft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are peculiar X-ray sources which are believed to be magnetars: ultra-magnetized neutron stars which emission is dominated by surface fields (often in excess of 1E14 G, i.e. well above the QED threshold).Spectral analysis is an important tool in magnetar astrophysics since it can provide key information on the emission mechanisms. The first attempts at modelling the persistent (i.e. outside bursts) soft X-ray (¡10 keV) spectra of AXPs proved that a model consisting of a blackbody (kT 0.3-0.6 keV) plus a power-law (photon index 2-4) could successfully reproduce the observed emission. Moreover, INTEGRAL observations have shown that, while in quiescence, magnetars emit substantial persistent radiation also at higher energies, up to a few hundreds of keV. However, a convincing physical interpretation of the various spectral components is still missing.In this talk I will focus on the interpretation of magnetar spectral properties during quiescence. I will summarise the present status of the art and the currents attempts to model the broadband persistent emission of magnetars (from IR to hard Xrays) within a self consistent, physical scenario.

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CALET UPPER LIMITS ON X-RAY AND GAMMA-RAY COUNTERPARTS OF GW151226

The Astrophysical Journal ◽

10.3847/2041-8205/829/1/l20 ◽

2016 ◽

Vol 829 (1) ◽

pp. L20 ◽

Cited By ~ 17

Author(s):

O. Adriani ◽

Y. Akaike ◽

K. Asano ◽

Y. Asaoka ◽

M. G. Bagliesi ◽

...

Keyword(s):

Gamma Ray ◽

X Ray ◽

Upper Limits

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Review of GRANAT Observations of AGNs

Symposium - International Astronomical Union ◽

10.1017/s0074180900174856 ◽

1994 ◽

Vol 159 ◽

pp. 63-72 ◽

Cited By ~ 2

Author(s):

E. Churazov ◽

M. Gilfanov ◽

A. Finoguenov ◽

R. Sunyaev ◽

M. Chernyakova ◽

...

Keyword(s):

Time Scales ◽

Gamma Ray ◽

Broad Band ◽

Band 3 ◽

X Rays ◽

X Ray ◽

X Ray Background

Brief review of AGNs observations in the X-ray / soft gamma-ray bands with the orbital observatory GRANAT is presented.For three well known bright objects (3C273, NGC4151 and Cen A) broad band (3 keV–few hundreds keV) spectra have been obtained. Imaging capabilities allowed accurate (several arcminutes) identification of these objects with sources of hard X-rays.The spectrum of NGC4151 above ≈ 50 keV was found to be much steeper than that in most of the previous observations, while in standard X-ray band the spectrum agrees with observed previously. The comparison of the observed spectra with that of the X-Ray Background (XRB) indicates that sources similar to NGC4151 could reproduce the shape of XRB spectrum in 3–60 keV band.Cen A was observed in the very low state during most of observations in 1990–1993, except for two observations in 1991. The variability of the hard X-ray flux has been detected on the time scales of several days.

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Broad-band study of high-synchrotron-peaked BL Lac object 1ES 1218+304

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1893 ◽

2020 ◽

Vol 496 (4) ◽

pp. 5518-5527

Author(s):

N Sahakyan

Keyword(s):

Energy Distribution ◽

Electron Energy ◽

Power Law ◽

Spectral Energy Distribution ◽

Broad Band ◽

Energy Distributions ◽

X Ray ◽

Bl Lac ◽

Photon Index ◽

Γ Ray

ABSTRACT The origin of the multiwavelength emission from the high-synchrotron-peaked BL Lac 1ES 1218+304 is studied using the data from SwiftUVOT/XRT, NuSTAR, and Fermi-LAT. A detailed temporal and spectral analysis of the data observed during 2008–2020 in the γ-ray (>100 MeV), X-ray (0.3–70 keV), and optical/UV bands is performed. The γ-ray spectrum is hard with a photon index of 1.71 ± 0.02 above 100 MeV. The SwiftUVOT/XRT data show a flux increase in the UV/optical and X-ray bands; the highest 0.3–3 keV X-ray flux was (1.13 ± 0.02) × 10−10 erg cm−2 s−1. In the 0.3–10 keV range, the averaged X-ray photon index is >2.0 which softens to 2.56 ± 0.028 in the 3–50 keV band. However, in some periods, the X-ray photon index became extremely hard (<1.8), indicating that the peak of the synchrotron component was above 1 keV, and so 1ES 1218+304 behaved like an extreme synchrotron BL Lac. The hardest X-ray photon index of 1ES 1218+304 was 1.60 ± 0.05 on MJD 58489. The time-averaged multiwavelength spectral energy distribution is modelled within a one-zone synchrotron self-Compton leptonic model using a broken power law and power law with an exponential cutoff electron energy distributions. The data are well explained when the electron energy distribution is $E_{\rm e}^{-2.1}$ extending up to γbr/cut ≃ (1.7 − 4.3) × 105, and the magnetic field is weak (B ∼ 1.5 × 10−2 G). By solving the kinetic equation for electron evolution in the emitting region, the obtained electron energy distributions are discussed considering particle injection, cooling, and escape.

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Multiwavelength observations of PSR J2032+4127 during the 2017 periastron passage

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1181 ◽

2020 ◽

Vol 495 (1) ◽

pp. 365-374 ◽

Cited By ~ 1

Author(s):

M Chernyakova ◽

D Malyshev ◽

P Blay ◽

B van Soelen ◽

S Tsygankov

Keyword(s):

Gamma Ray ◽

Broad Band ◽

Joint Analysis ◽

Spectral Evolution ◽

Optical Telescope ◽

X Ray ◽

Broad Band Emission ◽

Band Emission ◽

Mass Outflow ◽

Be Star

ABSTRACT PSR J2032+4127 is only the second known gamma-ray binary where it is confirmed that a young radio pulsar is in orbit around a Be-star. The interaction of the pulsar wind with the mass outflow from the companion leads to broad-band emission from radio up to TeV energies. In this paper we present results of optical monitoring of the 2017 periastron passage with the Nordic Optical Telescope. These observations are complemented by X-ray (Swift/XRT, NuSTAR) and GeV (Fermi/LAT) monitoring. Joint analysis of the evolution of the parameters of the H α line and the broad-band (X-ray to TeV) spectral shape allows us to propose a model linking the observed emission to the interaction of the pulsar and Be-star winds under the assumption of the inclined disc geometry. Our model allows the observed flux and spectral evolution of the system to be explained in a self-consistent way.

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