X-Ray Emission of the γ-ray-loud Young Radio Galaxy NGC 3894

Abstract The radio source 1146+596 is hosted by the elliptical/S0 galaxy NGC 3894, with a low-luminosity active nucleus. The radio structure is compact, suggesting a very young age for the jets in the system. Recently, the source has been confirmed as a high-energy (HE; >0.1 GeV) γ-ray emitter in the most recent accumulation of Fermi Large Area Telescope data. Here we report on the analysis of the archival Chandra X-ray Observatory data for the central part of the galaxy, consisting of a single 40 ks long exposure. We have found that the core spectrum is best fitted by a combination of an ionized thermal plasma with a temperature of ≃0.8 keV, and a moderately absorbed power-law component (photon index Γ = 1.4 ± 0.4, hydrogen column density N H/1022 cm−2 = 2.4 ± 0.7). We have also detected the iron Kα line at 6.5 ± 0.1 keV, with a large equivalent width of 1.0 − 0.5 + 0.9 keV. Based on the simulations of Chandra's point-spread function, we have concluded that while the soft thermal component is extended on the scale of the galaxy host, the hard X-ray emission within the narrow photon energy range 6.0–7.0 keV originates within the unresolved core (effectively the central kiloparsec radius). The line is therefore indicative of the X-ray reflection from a cold neutral gas in the central regions of NGC 3894. We discuss the implications of our findings in the context of the X-ray Baldwin effect. NGC 3894 is the first young radio galaxy detected in HE γ-rays with the iron Kα line.

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AstroSat view of GRS 1915+105 during the soft state: detection of HFQPOs and estimation of mass and spin

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3135 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5891-5901

Author(s):

H Sreehari ◽

Anuj Nandi ◽

Santabrata Das ◽

V K Agrawal ◽

Samir Mandal ◽

...

Keyword(s):

Broad Band ◽

Power Spectra ◽

Periodic Oscillation ◽

High Energy ◽

Energy Spectra ◽

Large Area ◽

X Ray ◽

Soft State ◽

Photon Index ◽

Area X

ABSTRACT We report the results of AstroSat observations of GRS 1915+105 obtained using 100 ks Guaranteed Time during the soft state. The colour–colour diagram indicates a variability class of δ with the detection of high-frequency quasi-periodic oscillation (HFQPO) in the power density spectra. The HFQPO is seen to vary in the frequency range of 67.96–70.62 Hz with percentage rms ∼0.83–1.90 per cent and significance varying from 1.63 to 7.75. The energy dependent power spectra show that the HFQPO features are dominant only in 6–25 keV energy band. The broad-band energy spectra (0.7–50 keV) of Soft X-ray Telescope and Large Area X-ray Proportional Counter modelled with nthComp and powerlaw imply that the source has an extended corona in addition to a compact ‘Comptonizing corona’ that produces high-energy emission and exhibits HFQPOs. The broad-band spectral modelling indicates that the source spectra are well described by thermal Comptonization with electron temperature (kTe) of 2.07–2.43 keV and photon index (Γnth) between 1.73 and 2.45 with an additional powerlaw component of photon index (ΓPL) between 2.94 and 3.28. The norm of nthComp component is high (∼8) during the presence of strong HFQPO and low (∼3) during the absence of HFQPO. Further, we model the energy spectra with the kerrbb model to estimate the accretion rate, mass, and spin of the source. Our findings indicate that the source accretes at super-Eddington rate of $1.17\!-\!1.31~ \dot{M}_{\rm Edd}$. Moreover, we find the mass and spin of the source as 12.44–13.09 M⊙ and 0.990–0.997 with $90{{\ \rm per\ cent}}$ confidence suggesting that GRS 1915+105 is a maximally rotating stellar mass X-ray binary black hole source.

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Exploring the multiphase medium in MKW 08: from the central active galaxy up to cluster scales

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935660 ◽

2019 ◽

Vol 629 ◽

pp. A82

Author(s):

A. Tümer ◽

F. Tombesi ◽

H. Bourdin ◽

E. N. Ercan ◽

M. Gaspari ◽

...

Keyword(s):

Galaxy Clusters ◽

Galactic Center ◽

Galaxy Cluster ◽

Pressure Profile ◽

Nearby Galaxy ◽

Cluster Galaxy ◽

X Ray ◽

The Galaxy ◽

Central Regions ◽

Photon Index

Context. The study of the brightest cluster galaxy (BCG) coronae embedded in noncool core (NCC) galaxy clusters is crucial to understand the BCG’s role in galaxy cluster evolution as well as the activation of the self-regulated cooling and heating mechanism in the central regions of galaxy clusters. Aims. We explore the X-ray properties of the intracluster medium (ICM) of the NCC galaxy cluster MKW 08 and the BCG corona, along with their interface region. With recent and deep archival Chandra observations, we study the BCG corona in detail, and with archival XMM-Newton observations, we investigate the implications of the central active galactic nuclei (AGN) on the BCG. Methods. We carry out imaging and spectral analyses of MKW 08 with archival XMM-Newton and Chandra X-ray observations. Results. Our spectral analysis suggests the presence of a central AGN by a power-law with a photon index of Γ ≃ 1.8 at the core of its BCG. Although the ICM does not exhibit a cluster scale cool core, the BCG manifests itself as a mini cool core characterized by a cooling time as short as 64 Myr at r = 3 kpc centered at the galaxy. The isothermality of the BCG corona seems to favor mechanical feedback from the central AGN as the major source of gas heating. The gas pressure profile of this mini cool core suggests that the BCG coronal gas reaches pressure equilibrium with the hotter and less dense ICM inside an interface of nearly constant pressure, delimited by radii 4 ≤ r ≤ 10 kpc at the galactic center. As revealed by the presence of a metal enriched tail (Z ≃ 0.5–0.9 Z⊙) extending up to 40 kpc, the BCG corona seems to be experiencing ram-pressure stripping by the surrounding ICM and/or interacting with a nearby galaxy, IC 1042.

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Investigating source confusion in PMN J1603–4904

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732338 ◽

2018 ◽

Vol 610 ◽

pp. L8 ◽

Cited By ~ 2

Author(s):

F. Krauß ◽

M. Kreter ◽

C. Müller ◽

A. Markowitz ◽

M. Böck ◽

...

Keyword(s):

Gamma Ray ◽

Radio Galaxy ◽

Radio Galaxies ◽

High Energy ◽

Large Area ◽

X Ray ◽

Long Baseline ◽

Localization Analysis ◽

Source Confusion ◽

Rare Class

PMN J1603–4904 is a likely member of the rare class of γ-ray emitting young radio galaxies. Only one other source, PKS 1718–649, has been confirmed so far. These objects, which may transition into larger radio galaxies, are a stepping stone to understanding AGN evolution. It is not completely clear how these young galaxies, seen edge-on, can produce high-energy γ rays. PMN J1603–4904 has been detected by TANAMI Very Long Baseline Interferometry (VLBI) observations and has been followed-up with multiwavelength observations. A Fermi Gamma-ray Space Telescope Large Area Telescope (Fermi-LAT) γ-ray source has been associated with this young galaxy in the LAT catalogs. We have obtained Chandra observations of the source to consider the possibility of source confusion due to the relatively large positional uncertainty of Fermi-LAT. The goal was to investigate the possibility of other X-ray bright sources in the vicinity of PMN J1603–4904 that could be counterparts to the γ-ray emission. With Chandra/ACIS, we find no other sources in the uncertainty ellipse of Fermi-LAT data, which includes an improved localization analysis of eight years of data. We further study the X-ray fluxes and spectra. We conclude that PMN J1603–4904 is indeed the second confirmed γ-ray bright young radio galaxy.

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Diffuse γ-ray emission toward the massive star-forming region, W40

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037580 ◽

2020 ◽

Vol 639 ◽

pp. A80

Author(s):

Xiao-Na Sun ◽

Rui-Zhi Yang ◽

Yun-Feng Liang ◽

Fang-Kun Peng ◽

Hai-Ming Zhang ◽

...

Keyword(s):

Cosmic Ray ◽

High Energy ◽

Young Star ◽

Gas Content ◽

Large Area ◽

Stellar Cluster ◽

Production Region ◽

Star Forming ◽

Photon Index ◽

Young Star Clusters

We report the detection of high-energy γ-ray signal towards the young star-forming region, W40. Using 10-yr Pass 8 data from the Fermi Large Area Telescope (Fermi-LAT), we extracted an extended γ-ray excess region with a significance of ~18σ. The radiation has a spectrum with a photon index of 2.49 ± 0.01. The spatial correlation with the ionized gas content favors the hadronic origin of the γ-ray emission. The total cosmic-ray (CR) proton energy in the γ-ray production region is estimated to be the order of 1047 erg. However, this could be a small fraction of the total energy released in cosmic rays (CRs) by local accelerators, presumably by massive stars, over the lifetime of the system. If so, W40, together with earlier detections of γ-rays from Cygnus cocoon, Westerlund 1, Westerlund 2, NGC 3603, and 30 Dor C, supports the hypothesis that young star clusters are effective CR factories. The unique aspect of this result is that the γ-ray emission is detected, for the first time, from a stellar cluster itself, rather than from the surrounding “cocoons”.

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X-ray Properties of 3C 111: Separation of Primary Nuclear Emission and Jet Continuum

Universe ◽

10.3390/universe6110219 ◽

2020 ◽

Vol 6 (11) ◽

pp. 219

Author(s):

Elena Fedorova ◽

B.I. Hnatyk ◽

V.I. Zhdanov ◽

A. Del Popolo

Keyword(s):

Accretion Disk ◽

Power Law ◽

Line Emission ◽

High Energy ◽

Power Law Model ◽

X Ray ◽

Additional Information ◽

Observational Dataset ◽

Simple Power ◽

Photon Index

3C111 is BLRG with signatures of both FSRQ and Sy1 in X-ray spectrum. The significant X-ray observational dataset was collected for it by INTEGRAL, XMM-Newton, SWIFT, Suzaku and others. The overall X-ray spectrum of 3C 111 shows signs of a peculiarity with the large value of the high-energy cut-off typical rather for RQ AGN, probably due to the jet contamination. Separating the jet counterpart in the X-ray spectrum of 3C 111 from the primary nuclear counterpart can answer the question is this nucleus truly peculiar or this is a fake “peculiarity” due to a significant jet contribution. In view of this question, our aim is to estimate separately the accretion disk/corona and non-thermal jet emission in the 3C 111 X-ray spectra within different observational periods. To separate the disk/corona and jet contributions in total continuum, we use the idea that radio and X-ray spectra of jet emission can be described by a simple power-law model with the same photon index. This additional information allows us to derive rather accurate values of these contributions. In order to test these results, we also consider relations between the nuclear continuum and the line emission.

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Correlation Between the V-I Characteristics of (0001) 4H-SiC PN Junctions Having Different Structural Features and Synchrotron X-ray Topography

MRS Proceedings ◽

10.1557/proc-1069-d07-21 ◽

2008 ◽

Vol 1069 ◽

Author(s):

Ryoji Kosugi ◽

Toyokazu Sakata ◽

Yuuki Sakuma ◽

Tsutomu Yatsuo ◽

Hirofumi Matsuhata ◽

...

Keyword(s):

High Energy ◽

Structural Features ◽

Incidence Geometry ◽

Voltage Source ◽

Large Area ◽

Chip Area ◽

Power Mosfets ◽

X Ray ◽

Pn Junctions ◽

The Difference

ABSTRACTIn practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

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Radio and X-ray Observations of the Restarted Radio Galaxy in the Galaxy Cluster CL 0838+1948

Galaxies ◽

10.3390/galaxies9040108 ◽

2021 ◽

Vol 9 (4) ◽

pp. 108

Author(s):

Simona Giacintucci ◽

Tracy Clarke ◽

Namir E. Kassim ◽

Wendy Peters ◽

Emil Polisensky

Keyword(s):

Radio Source ◽

Survey Data ◽

Radio Galaxy ◽

Galaxy Cluster ◽

Gas Emission ◽

Low Frequencies ◽

Nuclear Activity ◽

X Ray ◽

Hot Gas ◽

The Galaxy

We present VLA Low-band Ionosphere and Transient Experiment (VLITE) 338 MHz observations of the galaxy cluster CL 0838+1948. We combine the VLITE data with Giant Metrewave Radio Telescope 610 MHz observations and survey data. The central galaxy hosts a 250 kpc source whose emission is dominated by two large lobes at low frequencies. At higher frequencies, a pair of smaller lobes (∼30 kpc) is detected within the galaxy optical envelope. The observed morphology is consistent with a restarted radio galaxy. The outer lobes have a spectral index αout=1.6, indicating that they are old, whereas the inner lobes have αinn=0.6, typical for an active source. Spectral modeling confirms that the outer emission is a dying source whose nuclear activity switched off not more than 110 Myr ago. Using archival Chandra X-ray data, we compare the radio and hot gas emission. We find that the active radio source is contained within the innermost and X-ray brightest region, possibly a galactic corona. Alternatively, it could be the remnant of a larger cool core whose outer layers have been heated by the former epoch of activity that has generated the outer lobes.

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Fermi-LAT and WMAP observations of the supernova remnant Puppis A

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313009617 ◽

2013 ◽

Vol 9 (S296) ◽

pp. 295-299

Author(s):

Marie-Hélène Grondin ◽

John W. Hewitt ◽

Marianne Lemoine-Goumard ◽

Thierry Reposeur ◽

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Gamma Ray ◽

High Energy ◽

Radio Spectrum ◽

Wilkinson Microwave Anisotropy Probe ◽

Large Area ◽

X Ray ◽

Inverse Compton Scattering ◽

Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

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Energy-dependent nebula extent and spatially resolved spectra of the pulsar wind nebula 3C 58

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2338 ◽

2020 ◽

Vol 498 (2) ◽

pp. 1911-1919

Author(s):

Fang-Wu Lu ◽

Quan-Gui Gao ◽

Li Zhang

Keyword(s):

Surface Brightness ◽

Spectral Energy Distribution ◽

High Energy ◽

Spatial Variations ◽

Spectral Energy ◽

X Ray ◽

Spatially Resolved ◽

Photon Index ◽

Pulsar Wind ◽

Energy Dependent

ABSTRACT 3C 58 is a pulsar wind nebula (PWN) that shows an interesting energy-dependent nebula extent and spatial variations of the photon index and surface brightness in the X-ray band. These observations provide useful information with which to study the spatially dependent radiative cooling of electrons and the energy-dependent transport mechanisms within the nebula. In this paper, the energy-dependent nebula extent and spatially resolved spectra of this PWN are investigated in the framework of a spatially dependent particle transport model. The observations of the nebula, including the photon spectral energy distribution, spatial variations of the X-ray spectrum, and measurements of the nebula extent, can be naturally explained in this model. Our results show that the energy-dependent nebula extent favours an advection–diffusion scenario with advection-dominated transport, and the variations of the nebula extent with energy in the X-ray band can be attributed to the cooling losses of high-energy electrons affected by synchrotron burn-off. Particle diffusion plays an important role in modifying the spatial variations of the photon index and surface brightness in the X-ray band. The radial extents of the nebula at radio, GeV and TeV energies are predicted by the model, indicating that the nebula extent of 3C 58 varies with energy in these bands. The analyses show that the dependence of the adiabatic cooling rate and synchrotron radiation on the spectral index of injected particles is important for changing the nebula extent at different energies.

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NGC 3894: a young radio galaxy seen by Fermi-LAT

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937049 ◽

2020 ◽

Vol 635 ◽

pp. A185 ◽

Cited By ~ 4

Author(s):

G. Principe ◽

G. Migliori ◽

T. J. Johnson ◽

F. D’Ammando ◽

M. Giroletti ◽

...

Keyword(s):

Radio Galaxy ◽

Radio Galaxies ◽

High Energy ◽

Apparent Velocity ◽

Large Area ◽

Long Baseline ◽

Full Period ◽

Very Long Baseline Array ◽

High Energy Emission ◽

First Time

Context. According to radiative models, radio galaxies may produce γ-ray emission from the first stages of their evolution. However, very few such galaxies have been detected by the Fermi Large Area Telescope (LAT) so far. Aims. NGC 3894 is a nearby (z = 0.0108) object that belongs to the class of compact symmetric objects (CSOs, i.e., the most compact and youngest radio galaxies), which is associated with a γ-ray counterpart in the Fourth Fermi-LAT source catalog. Here we present a study of the source in the γ-ray and radio bands aimed at investigating its high-energy emission and assess its young nature. Methods. We analyzed 10.8 years of Fermi-LAT data between 100 MeV and 300 GeV and determined the spectral and variability characteristics of the source. Multi-epoch very long baseline array (VLBA) observations between 5 and 15 GHz over a period of 35years were used to study the radio morphology of NGC 3894 and its evolution. Results. NGC 3894 is detected in γ-rays with a significance >9σ over the full period, and no significant variability has been observed in the γ-ray flux on a yearly time-scale. The spectrum is modeled with a flat power law (Γ = 2.0 ± 0.1) and a flux on the order of 2.2 × 10−9 ph cm−2 s−1. For the first time, the VLBA data allow us to constrain with high precision the apparent velocity of the jet and counter-jet side to be βapp, NW = 0.132 ± 0.004 and βapp, SE = 0.065 ± 0.003, respectively. Conclusions. Fermi-LAT and VLBA results favor the youth scenario for the inner structure of this object, with an estimated dynamical age of 59 ± 5 years. The estimated range of viewing angle (10° < θ < 21°) does not exclude a possible jet-like origin of the γ-ray emission.

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