Non-thermal emission and spectral evolution properties of G54.1+0.3

2019 ◽  
Vol 487 (4) ◽  
pp. 5781-5787
Author(s):  
Ji-Yang Ren ◽  
Quan-Gui Gao ◽  
Huai-Zhen Li ◽  
Ju Ma ◽  
Shan-Shan Zhao ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Photon Emission ◽  
Dynamical Evolution ◽  
Spectral Energy ◽  
Model Parameters ◽  
Spectral Evolution ◽  
Proton Proton ◽  
X Ray ◽  
Γ Ray

ABSTRACT The multiband photon emission and spectral evolution of G54.1+0.3 are investigated in the framework of leptonic and leptonic–hadronic models. We model the spectral energy distribution (SED) of the pulsar wind nebula (PWN) and find that both the leptonic and leptonic–hadronic models can well reproduce the multiband observations of the nebula with appropriate model parameters. Combining with dynamical evolution of the PWN, we investigate the time evolution of photon SED and radiative luminosity in the X-ray and TeV γ-ray bands of G54.1+0.3. The results indicate that the synchrotron spectrum and radiative luminosity in the X-ray band of the PWN calculated with these two models have obvious differences as the age increases to about 4 kyr, and the largest difference is present at about 40 kyr. The γ-ray luminosity calculated by the leptonic–hadronic model shows that the contribution of TeV photons arising from the decay of neutral pions produced in proton–proton interaction also changes with time and is always important for modifying the TeV γ-ray spectrum of G54.1+0.3 during the evolution of the PWN.

scholarly journals Non-thermal emission in radio galaxy lobes – II. Centaurus A, Centaurus B, and NGC 6251

2019 ◽  
Vol 490 (2) ◽  
pp. 1489-1497 ◽  
Author(s):  
Massimo Persic ◽  
Yoel Rephaeli
Keyword(s):  
Thermal Emission ◽  
Background Radiation ◽  
Spectral Energy Distribution ◽  
Recent Analysis ◽  
Spectral Energy ◽  
Energetic Proton ◽  
X Ray ◽  
Radiation Fields ◽  
Γ Ray ◽  
Centaurus A

ABSTRACT Radio and γ-ray measurements of large lobes of several radio galaxies provide adequate basis for determining whether emission in these widely separated spectral regions is largely by energetic electrons. This is very much of interest as there is of yet no unequivocal evidence for a significant energetic proton component to account for γ-ray emission by neutral pion decay. A quantitative assessment of the pion yield spectral distribution necessitates full accounting of the local and background radiation fields in the lobes; indeed, doing so in our recent analysis of the spectral energy distribution of the Fornax A lobes considerably weakened previous conclusions on the hadronic origin of the emission measured by the Fermi satellite. We present the results of similar analyses of the measured radio, X-ray, and γ-ray emission from the lobes of Centaurus A, Centaurus B, and NGC 6251. The results indicate that the measured γ-ray emission from these lobes can be accounted for by Compton scattering of the radio-emitting electrons off the superposed radiation fields in the lobes; consequently, we set upper bounds on the energetic proton contents of the lobes.

scholarly journals Tracing the high energy emission of γ-ray detected radio loud quasars

2014 ◽  
Vol 10 (S313) ◽  
pp. 225-230
Author(s):  
Giulia Migliori
Keyword(s):  
Spectral Energy Distribution ◽  
High Energy ◽  
Host Galaxy ◽  
Spectral Energy ◽  
X Ray ◽  
Relativistic Jet ◽  
Quasar Jets ◽  
Γ Ray ◽  
High Energy Emission ◽  
Jet Power

AbstractWe present a multiwavelength study of the core and relativistic jet of the radio loud (RL) quasar RGB J1512+020A (z=0.20). We report the discovery of a bright, 13” extended X-ray jet with a short Chandra observation. We discuss the origin of the jet X-ray emission and its properties in comparison with sample of X-ray quasar jets. The broadband core spectrum is contributed by the emission of the central quasar, by a blazar component, responsible for the γ-ray emission detected by Fermi, and by the host galaxy. We model the non-thermal blazar spectral energy distribution (SED) and constrain the total jet power. The jet power inferred from the blazar SED modeling is in agreement with the values obtained from the total radio power, pointing to a jet that efficiently carries its power up to kiloparsec scales. The quasar emission appears intrinsically weak in the optical-UV band. The disk luminosity estimated from the broad emission lines is lower than the jet power, in agreement with recent results from observations and theory.

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 Multiwavelength characterization of the accreting millisecond X-ray pulsar and ultracompact binary IGR J17062–6143

2019 ◽  
Vol 488 (4) ◽  
pp. 4596-4606 ◽  
Author(s):  
J V Hernández Santisteban ◽  
V Cúneo ◽  
N Degenaar ◽  
J van den Eijnden ◽  
D Altamirano ◽  
...  
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Mass Transfer Rate ◽  
Current Data ◽  
Accretion Disc ◽  
Spectral Energy ◽  
Companion Star ◽  
X Ray ◽  
Binary Evolution

ABSTRACT IGR J17062–6143 is an ultracompact X-ray binary (UCXB) with an orbital period of 37.96 min. It harbours a millisecond X-ray pulsar that is spinning at 163 Hz and and has continuously been accreting from its companion star since 2006. Determining the composition of the accreted matter in UCXBs is of high interest for studies of binary evolution and thermonuclear burning on the surface of neutron stars. Here, we present a multiwavelength study of IGR J17062–6143 aimed to determine the detailed properties of its accretion disc and companion star. The multi-epoch photometric UV to near-infrared spectral energy distribution (SED) is consistent with an accretion disc Fν ∝ ν1/3. The SED modelling of the accretion disc allowed us to estimate an outer disc radius of $R_{\rm out} = 2.2^{+0.9}_{-0.4} \times 10^{10}$ cm and a mass-transfer rate of $\dot{m} = 1.8^{+1.8}_{-0.5}\times 10^{-10}$ M⊙ yr−1. Comparing this with the estimated mass-accretion rate inferred from its X-ray emission suggests that ≳90 per cent of the transferred mass is lost from the system. Moreover, our SED modelling shows that the thermal emission component seen in the X-ray spectrum is highly unlikely from the accretion disc and must therefore represent emission from the surface of the neutron star. Our low-resolution optical spectrum revealed a blue continuum and no emission lines, i.e. lacking H and He features. Based on the current data we cannot conclusively identify the nature of the companion star, but we make recommendations for future study that can distinguish between the different possible evolution histories of this X-ray binary. Finally, we demonstrate how multiwavelength observations can be effectively used to find more UCXBs among the LMXBs.

scholarly journals Leptonic modelling of Ton 599 in flare and quiescent states

2019 ◽  
Vol 492 (1) ◽  
pp. 72-78
Author(s):  
S R Patel ◽  
V R Chitnis
Keyword(s):  
Dynamic Range ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Spectral Energy ◽  
Model Parameters ◽  
Quiescent State ◽  
High Flux ◽  
Two Component ◽  
Γ Ray ◽  
Flux State

ABSTRACT The flat-spectrum radio quasar Ton 599 attained its highest ever γ-ray flux state during the first week of 2017 November. Observations of the source by the Swift satellite during this period made it possible to generate a simultaneous high flux state broad-band spectral energy distribution (SED). The high flux state activity of Ton 599 is modelled in this work for the first time. We modelled one high flux state and one quiescent state of the source in order to characterize the evolution of SEDs covering the entire dynamic range of γ-ray flux observed by Fermi-LAT. An attempt was made to model the 2017 November state of the source using an external Compton (EC) model in the leptonic scenario. We reproduce the broad-band flaring state SED using a two-component leptonic emission model. We considered one component as an EC+synchrotron self-Compton (SSC) component and the other as pure SSC, lying further down in the jet. The EC+SSC component was located outside the broad-line region (BLR). It mainly reproduces the GeV emission by an EC process with a dusty torus (DT) photon field providing seed photons. We reproduce the broad-band emission from Ton 599 satisfactorily during its peculiar flaring state with a leptonic two-component model. Besides this, we compare the model parameters of a quiescent-state SED with the available average state model parameters in the literature.

scholarly journals The first broad-band X-ray view of the narrow-line Seyfert 1 Ton S180

2020 ◽  
Vol 497 (2) ◽  
pp. 2352-2370 ◽  
Author(s):  
G A Matzeu ◽  
E Nardini ◽  
M L Parker ◽  
J N Reeves ◽  
V Braito ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Outer Part ◽  
Spectral Energy ◽  
X Rays ◽  
Narrow Line ◽  
X Ray ◽  
Extreme Uv ◽  
Reflection Grating

ABSTRACT We present joint XMM–Newton and NuSTAR observations of the ‘bare’ narrow-line Seyfert 1 Ton S180 (z = 0.062), carried out in 2016 and providing the first hard X-ray view of this luminous galaxy. We find that the 0.4–30 keV band cannot be self-consistently reproduced by relativistic reflection models, which fail to account simultaneously for the soft and hard X-ray emission. The smooth soft excess prefers extreme blurring parameters, confirmed by the nearly featureless nature of the Reflection Grating Spectrometer (RGS) spectrum, while the moderately broad Fe K line and the modest hard excess above 10 keV appear to arise in a milder gravity regime. By allowing a different origin of the soft excess, the broad-band X-ray spectrum and overall spectral energy distribution (SED) are well explained by a combination of (a) direct thermal emission from the accretion disc, dominating from the optical to the far/extreme UV; (b) Comptonization of seed disc photons by a warm (kTe ∼ 0.3 keV) and optically thick (τ ∼ 10) corona, mostly contributing to the soft X-rays; (c) Comptonization by a standard hot ($kT_{\rm \mathrm{ e}}\gtrsim 100$ keV) and optically thin (τ < 0.5) corona, responsible for the primary X-ray continuum; and (d) reflection from the mid/outer part of the disc. The two coronae are suggested to be rather compact, with $R_{\rm hot}\lesssim R_{\rm warm}\lesssim 10\, r_{\rm g}$. Our SED analysis implies that Ton S180 accretes at super-Eddington rates. This is a key condition for the launch of a wind, marginal (i.e. 3.1σ significance) evidence of which is indeed found in the RGS spectrum.

scholarly journals Identification of a new ultraluminous X-ray source in NGC 1316

2020 ◽  
Vol 499 (4) ◽  
pp. 5682-5689
Author(s):  
S Allak ◽  
A Akyuz ◽  
N Aksaker ◽  
M Ozdogan Ela ◽  
S Avdan ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Spectral Energy ◽  
Model Parameters ◽  
Wide Field ◽  
X Ray ◽  
Blackbody Model

ABSTRACT In this study, we report identification of a new ultraluminous X-ray source (ULX) named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.1 × 1039 erg s−1 using the two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and was included in the source list of the NGC 1316 as CXOUJ032240.8−371224 with a luminosity of 5.7 × 1038 erg s−1. Present luminosity implies a luminosity increase of a factor of ∼4. The best-fitting spectral model parameters indicate that X-7 has a relatively hot disc and hard spectra. If explained by a disc blackbody model, the mass of compact object is estimated as ∼8 M⊙ which is in the range of a stellar-mass black hole. The X-7 shows a relatively long-term count rate variability while no short-term variability is observed. We also identified a unique optical candidate within 0.22 arcsec error circle at 95 per cent confidence level for X-7 using the archival HST/ACS (Hubble Space Telescope/Advanced Camera for Surveys) and HST/WFC3 (The Wide Field Camera 3) data. Absolute magnitude (MV) of this candidate is −7.8 mag. Its spectral energy distribution is adequately fitted a blackbody model with a temperature of 3100 K indicating an M type supergiant, assuming the donor star dominates the optical emission. In addition, we identified a transient ULX candidate (XT-1) located 6 arcsec away from X-7 has a (high) luminosity of ∼1039 erg s−1 with no visible optical candidate.

scholarly journals Searches for pulsar-like candidates from unidentified objects in the Third Catalog of Hard Fermi-LAT Sources with machine learning techniques

2020 ◽  
Vol 495 (1) ◽  
pp. 1093-1109 ◽  
Author(s):  
C Y Hui ◽  
Jongsu Lee ◽  
K L Li ◽  
Sangin Kim ◽  
Kwangmin Oh ◽  
...  
Keyword(s):  
Machine Learning ◽  
Globular Clusters ◽  
Classification Scheme ◽  
Spectral Energy Distribution ◽  
Machine Learning Techniques ◽  
Spectral Energy ◽  
Periodic Signal ◽  
X Ray ◽  
The Third ◽  
Γ Ray

ABSTRACT We report the results of searching pulsar-like candidates from the unidentified objects in the Third Catalog of Hard Fermi-LAT Sources (3FHL). Using a machine-learning-based classification scheme with a nominal accuracy of $\sim \!98{{\, \rm per\, cent}}$, we have selected 27 pulsar-like objects from 200 unidentified 3FHL sources for an identification campaign. Using archival data, X-ray sources are found within the γ-ray error ellipses of 10 3FHL pulsar-like candidates. Within the error circles of the much better constrained X-ray positions, we have also searched for the optical/infrared counterparts and examined their spectral energy distributions. Among our shortlisted candidates, the most secure identification is the association of 3FHL J1823.3–1339 and its X-ray counterpart with the globular cluster Mercer 5. The γ-rays from the source can be contributed by a population of millisecond pulsars residing in the cluster. This makes Mercer 5 as one of the slowly growing hard γ-ray population of globular clusters with emission >10 GeV. Very recently, another candidate picked by our classification scheme, 3FHL J1405.1–6118, has been identified as a new γ-ray binary with an orbital period of 13.7 d. Our X-ray analysis with a short Chandra observation has found a possible periodic signal candidate of ∼1.4 h and a putative extended X-ray tail of ∼20 arcsec long. Spectral energy distribution of its optical/infrared counterpart conforms with a blackbody of Tbb ∼ 40 000 K and Rbb ∼ 12 R⊙ at a distance of 7.7 kpc. This is consistent with its identification as an early O star as found by infrared spectroscopy.

MODELING THE MULTIWAVELENGTH SPECTRA AND VARIABILITY OF 3C 66A IN 2003–2004

2007 ◽  
Vol 22 (19) ◽  
pp. 3147-3154
Author(s):  
M. JOSHI ◽  
M. BÖTTCHER
Keyword(s):  
Background Radiation ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Emission Region ◽  
X Ray ◽  
Central Engine ◽  
Infrared Background ◽  
Very High Energy ◽  
Γ Ray

The BL Lac object 3C 66A was the target of an intensive multiwavelength monitoring campaign organized in 2003–2004. During the campaign, its spectral energy distribution (SED) was measured and flux measurements from radio to X-ray frequencies as well as upper limits in the very high energy (VHE) γ-ray regime were obtained. Here, we reproduce the SED and optical spectral variability pattern observed during our multiwavelength campaign using a time-dependent leptonic jet model. Our model could successfully simulate the observed SED and optical light curves and predict an intrinsic cutoff value for the VHE γ-ray emission at ~4 GeV implying the effect of the optical depth due to the intergalactic infrared background radiation (IIBR) to be negligible. Also, the contribution of external Comptonization (EIC), due to the presence of a broad-line region (BLR), in the emission of γ-ray photons could be significant early-on when the emission region is very close to the central engine but as it travels farther out, the production mechanism of hard X-ray and γ-ray photons becomes dominated by synchrotron self-Compton mechanism (SSC).

A disc reflection model for ultra-soft narrow-line Seyfert 1 galaxies

2020 ◽  
Vol 498 (3) ◽  
pp. 3888-3901
Author(s):  
Jiachen Jiang ◽  
Luigi C Gallo ◽  
Andrew C Fabian ◽  
Michael L Parker ◽  
Christopher S Reynolds
Keyword(s):  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Continuum Emission ◽  
Spectral Energy ◽  
Narrow Line ◽  
Ionization State ◽  
X Ray ◽  
Reflection Model ◽  
Photon Index

ABSTRACT We present a detailed analysis of the XMM–Newton observations of five narrow-line Seyfert 1 galaxies (NLS1s). They all show very soft continuum emission in the X-ray band with a photon index of Γ ≳ 2.5. Therefore, they are referred to as ‘ultra-soft’ NLS1s in this paper. By modelling their optical/UV–X-ray spectral energy distribution (SED) with a reflection-based model, we find indications that the disc surface in these ultra-soft NLS1s is in a higher ionization state than other typical Seyfert 1 AGN. Our best-fitting SED models suggest that these five ultra-soft NLS1s have an Eddington ratio of λEdd = 1–20 assuming available black hole mass measurements. In addition, our models infer that a significant fraction of the disc energy in these ultra-soft NLS1s is radiated away in the form of non-thermal emission instead of the thermal emission from the disc. Due to their extreme properties, X-ray observations of these sources in the iron band are particularly challenging. Future observations, e.g. from Athena, will enable us to have a clearer view of the spectral shape in the iron band and thus distinguish the reflection model from other interpretations of their broad-band spectra.

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