scholarly journals IGR J17503–2636: a candidate supergiant fast X-ray transient

2019 ◽  
Vol 624 ◽  
pp. A142 ◽  
Author(s):  
C. Ferrigno ◽  
E. Bozzo ◽  
A. Sanna ◽  
G. K. Jaisawal ◽  
J. M. Girard ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Neutron Star ◽  
Energy Distribution ◽  
Power Law ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
X Ray ◽  
Broad Feature

The object IGR J17503–2636 is a hard X-ray transient discovered by INTEGRAL on 2018 August 11. This was the first ever reported X-ray emission from this source. Following the discovery, follow-up observations were carried out with Swift, Chandra, NICER, and NuSTAR. Here we report on the analysis of all of these X-ray data and the results obtained. Based on the fast variability in the X-ray domain, the spectral energy distribution in the 0.5–80 keV energy range, and the reported association with a highly reddened OB supergiant at ∼10 kpc, we conclude that IGR J17503–2636 is most likely a relatively faint new member of the supergiant fast X-ray transients. Spectral analysis of the NuSTAR data revealed a broad feature in addition to the typical power-law with exponential roll-over at high energy. This can be modeled either in emission or as a cyclotron scattering feature in absorption. If confirmed by future observations, this feature would indicate that IGR J17503–2636 hosts a strongly magnetized neutron star with B ∼ 2 × 1012 G.

scholarly journals The spectral energy distribution of an X-ray pair halo from a gamma-ray source with a power-law continuum

2021 ◽  
Vol 2145 (1) ◽  
pp. 012013
Author(s):  
A Eungwanichayapant ◽  
W Luangtip
Keyword(s):  
Energy Distribution ◽  
Power Law ◽  
Gamma Ray ◽  
Energy Levels ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Maximum Energy ◽  
Spectral Energy ◽  
Power Indices ◽  
X Ray

Abstract Interactions between Very High Energy (VHE) gamma-rays from Active Galactic Nuclei (AGNs) and infrared photons from the Extragalactic Background Light (EBL) can start electromagnetic cascades. If the extragalactic magnetic field near a host galaxy is strong enough (∼1 µG), the cascades would develop isotropically around the AGN. As a result, the electron/positron pairs created along the development of the cascades would create an X-ray halo via synchrotron radiation process. It is believed that the VHE gamma-ray spectra from the AGNs could be approximated by a power-law model which is truncated at high energy end (i.e. maximum energy). In this work we studied the X-ray Spectral Energy Distribution (SED) of the halo generated from the AGN spectra with different power indices and maximum energy levels. The results showed that the SEDs were slightly higher and broader, as they were obtaining higher flux if the power indices were lower. On the other hand, the SEDs were sensitive to the maximum energy levels between 100-300 TeV. More flux could be obtained from the higher maximum energy. However, we found that the SED becomes insensitive to the varied parameters when the maximum energy and the power index are > 500 TeV and < 1.5, respectively.

scholarly journals A NuSTAR view of powerful γ-ray loud blazars

2019 ◽  
Vol 627 ◽  
pp. A72 ◽  
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.

scholarly journals The Soft X-ray Excesses Observed by ROSAT

1994 ◽  
Vol 159 ◽  
pp. 338-338
Author(s):  
R. Walter ◽  
H.H. Fink
Keyword(s):  
Power Law ◽  
Spectral Energy Distribution ◽  
Seyfert Galaxies ◽  
High Energy ◽  
Wide Distribution ◽  
Spectral Energy ◽  
Spectral Slope ◽  
X Ray ◽  
Object A ◽  
The Mean

The properties of the soft X-ray excesses of bright Seyfert 1 galaxies and Quasars are described using the observations obtained with the PSPC (0.1–2.4 keV) detector of the XRT telescope aboard ROSAT during the ROSAT all sky survey (RASS). The sample consists of 58 Seyfert 1 type AGN detected with more than 300 counts during the RASS and observed at least once with IUE.The soft X-ray photon indices of our sample members range from 1.6 to 3.4 in a wide distribution (< Γ > = 2.50, σ = 0.48). The width of the distribution is considerably larger than the mean statistical uncertainty on the individual spectral slopes (σ = 0.33). Excepting for IC 4329A and Mrk 766, the mean contribution of absorbing cold matter intrinsic to the Seyfert galaxies of our sample to the absorbing column density is less than 1020cm−2. In IC 4329A and Mrk 766 intrinsic absorbtion is observed at soft X-ray. Both sources are also strongly reddened by dust.An excess of soft X-ray flux is detected in 90% of the sources above the exptrapolation of the hard X-ray power law. It can be shown that the PSPC spectral slope is a measure of the strength of the soft X-ray excess. If the reddened sources are excluded, a correlation appears between the strength of the ultraviolet blue bump and the soft X-ray photon index (figure 1). The ratio of the ultraviolet to infrared fluxes and the ultraviolet spectral slope are also related to the strength of the blue bump. The observations are compatible with a model where most of the spectral variations arising among the sources studied are driven by the strength of the bump component, which varies by a factor of 100 from object to object. A bump model consisting of a power law with a high energy cutoff at 80 eV can fit most of the sources. In any case, the spectral energy distribution of the ultraviolet to soft X-ray bump is characterised by vFv(1375 Å) = (1–5) ∫ε > 150eVFεdε.

scholarly journals Hard X-ray-to-radio energy distributions in starburst galaxies

1999 ◽  
Vol 193 ◽  
pp. 592-593 ◽  
Author(s):  
Miguel Cerviño ◽  
J. Miguel Mas-Hesse
Keyword(s):  
Energy Distribution ◽  
Mechanical Energy ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Starburst Galaxies ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
High Energy Emission ◽  
X Ray Binaries

We present in this contribution the predictions on the multiwavelength spectral energy distribution of our evolutionary population synthesis models including single and binary stellar systems. The high energy computations include the emission associated to X-ray binaries and supernovae remnants, as well as the mechanical energy released into the interstellar medium, which can be partially reprocessed into thermal X-rays. With these components we compute the spectral energy distribution of starburst galaxies from X-ray to radio ranges, and analyze finally the effects of the high energy emission on the H and He ionizing continuum.

Investigating the multiband non-thermal emission of the 100 TeV source eHWC J2019+368 with a pulsar wind nebula scenario

2020 ◽  
Vol 498 (4) ◽  
pp. 4901-4905
Author(s):  
Jun Fang ◽  
Lu Wen ◽  
Huan Yu ◽  
Songzhan Chen
Keyword(s):  
Energy Distribution ◽  
Power Law ◽  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Recent Measurement ◽  
Inverse Compton Scattering ◽  
Γ Rays ◽  
Pulsar Wind

ABSTRACT eHWC J2019+368 is one of the sources emitting γ-rays with energies higher than 100 TeV based on the recent measurement with the High Altitude Water Cherenkov Observatory (HAWC), and the origin is still in debate. The pulsar PSR J2021+3651 is spatially coincident with the TeV source. We investigate theoretically whether the multiband non-thermal emission of eHWC J2019+368 can originate from the pulsar wind nebula (PWN) G75.2+0.1 powered by PSR J2021+3651. In the model, the spin-down power of the pulsar is transferred to high-energy particles and magnetic field in the nebula. As the particles with an energy distribution of either a broken power law or a power law continually injected into the nebula, the multiband non-thermal emission is produced via synchrotron radiation and inverse Compton scattering. The spectral energy distribution of the nebula from the model with the reasonable parameters is generally consistent with the detected radio, X-ray, and TeV γ-ray fluxes. Our study supports that the PWN has the ability to produce the TeV γ-rays of eHWC J2019+368, and the most energetic particles in the nebula have energies up to about 0.4 PeV.

scholarly journals Detailed spectral and morphological analysis of the shell type supernova remnant RCW 86

2018 ◽  
Vol 612 ◽  
pp. A4 ◽  
Author(s):  
◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
A. G. Akhperjanian ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Spectral Index ◽  
Supernova Remnant ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
X Ray ◽  
Type Ia Supernova ◽  
Type Ia

Aim. We aim for an understanding of the morphological and spectral properties of the supernova remnant RCW 86 and for insights into the production mechanism leading to the RCW 86 very high-energy γ-ray emission.Methods. We analyzed High Energy Spectroscopic System (H.E.S.S.) data that had increased sensitivity compared to the observations presented in the RCW 86 H.E.S.S. discovery publication. Studies of the morphological correlation between the 0.5–1 keV X-ray band, the 2–5 keV X-ray band, radio, and γ-ray emissions have been performed as well as broadband modeling of the spectral energy distribution with two different emission models.Results. We present the first conclusive evidence that the TeV γ-ray emission region is shell-like based on our morphological studies. The comparison with 2–5 keV X-ray data reveals a correlation with the 0.4–50 TeV γ-ray emission. The spectrum of RCW 86 is best described by a power law with an exponential cutoff at Ecut = (3.5 ± 1.2stat) TeV and a spectral index of Γ ≈ 1.6 ± 0.2. A static leptonic one-zone model adequately describes the measured spectral energy distribution of RCW 86, with the resultant total kinetic energy of the electrons above 1 GeV being equivalent to ~0.1% of the initial kinetic energy of a Type Ia supernova explosion (1051 erg). When using a hadronic model, a magnetic field of B ≈ 100 μG is needed to represent the measured data. Although this is comparable to formerly published estimates, a standard E−2 spectrum for the proton distribution cannot describe the γ-ray data. Instead, a spectral index of Γp ≈ 1.7 would be required, which implies that ∼7 × 1049/ncm−3 has been transferred into high-energy protons with the effective density ncm−3 = n/1 cm−3. This is about 10% of the kinetic energy of a typical Type Ia supernova under the assumption of a density of 1 cm−3.

scholarly journals Multimessenger observations of counterparts to IceCube-190331A

2020 ◽  
Vol 497 (3) ◽  
pp. 2553-2561
Author(s):  
Felicia Krauß ◽  
Emily Calamari ◽  
Azadeh Keivani ◽  
Alexis Coleiro ◽  
Phil A Evans ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Ultra High Energy ◽  
X Ray ◽  
High Energy Cosmic Rays ◽  
High Energies ◽  
Neutrino Event ◽  
Promising Tool ◽  
Localization Region

ABSTRACT High-energy neutrinos are a promising tool for identifying astrophysical sources of high and ultra-high energy cosmic rays (UHECRs). Prospects of detecting neutrinos at high energies (≳TeV) from blazars have been boosted after the recent association of IceCube-170922A and TXS 0506+056. We investigate the high-energy neutrino, IceCube-190331A, a high-energy starting event (HESE) with a high likelihood of being astrophysical in origin. We initiated a Swift/XRT and UVOT tiling mosaic of the neutrino localization and followed up with ATCA radio observations, compiling a multiwavelength spectral energy distribution (SED) for the most likely source of origin. NuSTAR observations of the neutrino location and a nearby X-ray source were also performed. We find two promising counterpart in the 90 per cent confidence localization region and identify the brightest as the most likely counterpart. However, no Fermi/LAT γ-ray source and no prompt Swift/BAT source is consistent with the neutrino event. At this point, it is unclear whether any of the counterparts produced IceCube-190331A. We note that the Helix Nebula is also consistent with the position of the neutrino event and we calculate that associated particle acceleration processes cannot produce the required energies to generate a high-energy HESE neutrino.

scholarly journals Spectral Energy Distribution in X-Ray Beam as a Function of Wavelength*

1952 ◽  
Vol 42 (1) ◽  
pp. 6 ◽  
Author(s):  
M. A. Greenfield ◽  
R. D. Specht ◽  
P. M. Kratz ◽  
Katherine Hand
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
X Ray

scholarly journals Constraining X-ray emission in HBL blazars using multiwavelength observations

2020 ◽  
Vol 496 (2) ◽  
pp. 1295-1306
Author(s):  
Alicja Wierzcholska ◽  
Stefan J Wagner
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Neutral Hydrogen ◽  
High Energy ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Additional Absorption ◽  
X Ray ◽  
Uv Excess ◽  
Survey Results

ABSTRACT The X-ray spectrum of extreme high-energy peaked BL Lac-type blazars is located in the synchrotron branch of the broad-band spectral energy distribution (SED), at energies below the peak. A joint fit of the extrapolated X-ray spectra together with a host galaxy template allows characterizing the synchrotron branch in the SED. The X-ray spectrum is usually characterized either with a pure or a curved power-law model. In the latter case, however, it is hard to distinguish an intrinsic curvature from excess absorption. In this paper, we focus on five well-observed blazars: 1ES 0229+200, PKS 0548−322, RX J 1136+6737, 1ES 1741+196, and 1ES 2344+514. We constrain the infrared to X-ray emission of these five blazars using a model that is characterized by the host galaxy, spectral curvature, absorption, and ultraviolet (UV) excess to separate these spectral features. In the case of four sources, namely 1ES 0229+200, PKS 0548−322, 1ES 1741+196, and 1ES 2344+514, the spectral fit with the atomic neutral hydrogen from the Leiden Argentina Bonn Survey results in a significant UV excess present in the broad-band SED. Such excess can be interpreted as an additional component, for example, a blue bump. However, in order to describe spectra of these blazars without such excess, additional absorption to the atomic neutral hydrogen from the Leiden Argentina Bonn Survey is needed.

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