scholarly journals Multi-wavelength campaign on NCG 7469

2018 ◽  
Vol 615 ◽  
pp. A163 ◽  
Author(s):  
R. Middei ◽  
S. Bianchi ◽  
M. Cappi ◽  
P.-O. Petrucci ◽  
F. Ursini ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Optical Depth ◽  
Spherical Geometry ◽  
Relativistic Effects ◽  
Seyfert Galaxy ◽  
High Energy ◽  
Joint Analysis ◽  
Photon Index ◽  
Multi Wavelength ◽  
Average Flux

We conducted a multi-wavelength 6-month campaign to observe the Seyfert Galaxy NGC 7469, using the space-based observatories HST, Swift, XMM-Newton and NuSTAR. We report the results of the spectral analysis of the seven simultaneous XMM-Newton and NuSTAR observations. The source shows significant flux variability within each observation, but the average flux is less variable among the different pointings of our campaign. Our spectral analysis reveals a prominent narrow neutral Fe Kα emission line in all the spectra and weaker contributions from Fe Kβ, neutral Ni Kα, and ionized iron. We find no evidence for variability or relativistic effects acting on the emission lines, which indicates that they originate from distant material. In the joint analysis of XMM-Newton and NuSTAR data, a constant photon index is found (Γ = 1.78 ± 0.02) together with a high energy cut-off Ecut = 170−40+60 keV. Adopting a self-consistent Comptonization model, these values correspond to an average coronal electron temperature of kT = 45−12+15 keV and, assuming a spherical geometry, an optical depth τ = 2.6 ± 0.9. The reflection component is consistent with being constant and the reflection fraction is in the range R = 0.3−0.6. A prominent soft excess dominates the spectra below 4 keV. This is best fit with a second Comptonization component, arising from a warm corona with an average kT = 0.67 ± 0.03 keV and a corresponding optical depth τ = 9.2 ± 0.2.

scholarly journals Multi-wavelength Behaviour of III Zw2

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.

scholarly journals NuSTAR view of the Seyfert galaxy HE 0436-4717

2018 ◽  
Vol 618 ◽  
pp. A167 ◽  
Author(s):  
R. Middei ◽  
F. Vagnetti ◽  
F. Tombesi ◽  
S. Bianchi ◽  
A. Marinucci ◽  
...  
Keyword(s):  
Lower Limit ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
High Energy ◽  
Consistent Model ◽  
Photon Index ◽  
Iron Abundance ◽  
Primary Power ◽  
Hot Corona ◽  
Reflection Component

We present the multi-epoch spectral analysis of HE 0436-4717, a bright Seyfert 1 galaxy serendipitously observed by the high energy satellite NuSTAR four times between December 2014 and December 2015. The source flux shows modest variability within each pointing and among the four observations. Spectra are well modelled in terms of a weakly variable primary power law with constant photon index (Γ = 2.01 ± 0.08). A constant narrow Fe Kα emission line suggests that this feature has an origin far from the central black hole, while a broad relativistic component is not required by the data. The Compton reflection component is also constant in flux with a corresponding reflection fraction R = 0.7+0.2−0.3. The iron abundance is compatible with solar (AFe = 1.2+1.4−0.4), and a lower limit for the high energy cut-off Ec > 280 keV is obtained. Adopting a self-consistent model accounting for a primary Comptonized continuum, we obtain a lower limit for the hot corona electron temperature kTe > 65 keV and a corresponding upper limit for the coronal optical depth of τe < 1.3. The results of the present analysis are consistent with the locus of local Seyfert galaxies in the kTe − τe and temperature-compactness diagrams.

scholarly journals NuSTAR/XMM–Newton monitoring of the Seyfert 1 galaxy HE 1143-1810

2020 ◽  
Vol 634 ◽  
pp. A92 ◽  
Author(s):  
F. Ursini ◽  
P.-O. Petrucci ◽  
S. Bianchi ◽  
G. Matt ◽  
R. Middei ◽  
...  
Keyword(s):  
Optical Depth ◽  
Broad Band ◽  
Spherical Geometry ◽  
High Energy ◽  
Band Spectrum ◽  
X Ray ◽  
Uv Emission ◽  
Two Phases ◽  
Hot Corona

Aims. We test the two-corona accretion scenario for active galactic nuclei in the case of the “bare” Seyfert 1 galaxy HE 1143-1810. Methods. We perform a detailed study of the broad-band UV–X-ray spectral properties and of the short-term variability of HE 1143-1810. We present results of a joint XMM–Newton and NuSTAR monitoring of the source, consisting of 5 × 20 ks observations, each separated by 2 days, performed in December 2017. Results. The source is variable in flux among the different observations, and a correlation is observed between the UV and X-ray emission. Moderate spectral variability is observed in the soft band. The time-averaged X-ray spectrum exhibits a cut-off at ∼100 keV consistent with thermal Comptonization. We detect an iron Kα line consistent with being constant during the campaign and originating from a mildly ionized medium. The line is accompanied by a moderate, ionized reflection component. A soft excess is clearly present below 2 keV and is well described by thermal Comptonization in a “warm” corona with a temperature of ∼0.5 keV and a Thomson optical depth of ∼17 − 18. For the hot hard X-ray emitting corona, we obtain a temperature of ∼20 keV and an optical depth of ∼4 assuming a spherical geometry. A fit assuming a jet-emitting disc (JED) for the hot corona also provides a nice description of the broad-band spectrum. In this case, the data are consistent with an accretion rate varying between ∼0.7 and ∼0.9 in Eddington units and a transition between the outer standard disc and the inner JED at ∼20 gravitational radii. Conclusions. The broad-band high-energy data agree with an accretion flow model consisting of two phases: an outer standard accretion disc with a warm upper layer, responsible for the optical–UV emission and the soft X-ray excess, and an inner slim JED playing the role of a hard X-ray emitting hot corona.

scholarly journals Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516

2021 ◽  
Author(s):  
V L Oknyansky ◽  
M S Brotherton ◽  
S S Tsygankov ◽  
A V Dodin ◽  
D-W Bao ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
Small Time ◽  
High State ◽  
X Ray ◽  
Reverberation Mapping ◽  
Spectroscopic Monitoring ◽  
Measured Time ◽  
Photon Index ◽  
Multi Wavelength ◽  
Balmer Lines

Abstract We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC 3516 carried out in 2018 to 2020 covering the wavelength range from the X-ray to the optical. The facilities included the telescopes of the CMO SAI MSU, the 2.3-m WIRO telescope, and the XRT and UVOT of Swift. We found that NGC 3516 brightened to a high state and could be classified as Sy1.5 during the late spring of 2020. We have measured time delays in the responses of the Balmer and He II λ4686 lines to continuum variations. In the case of the best-characterized broad Hβ line, the delay to continuum variability is about 17 days in the blue wing and is clearly shorter, 9 days, in the red, which is suggestive of inflow. As the broad lines strengthened, the blue side came to dominate the Balmer lines, resulting in very asymmetric profiles with blueshifted peaks during this high state. During the outburst the X-ray flux reached its maximum on 1 April 2020 and it was the highest value ever observed for NGC 3516 by the Swift observatory. The X-ray hard photon index became softer, ∼1.8 in the maximum on 21 Apr 2020 compared to the mean ∼0.7 during earlier epochs before 2020. We have found that the UV and optical variations correlated well (with a small time delay of 1–2 days) with the X-ray until the beginning of April 2020, but later, until the end of Jun. 2020, these variations were not correlated. We suggest that this fact may be a consequence of partial obscuration by Compton-thick clouds crossing the line of sight.

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

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”.

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

Universe ◽  
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.

THE ABSORPTION OF HIGH-ENERGY RADIATION, A MONTE CARLO STUDY: II. SPHERICAL GEOMETRY

1963 ◽  
Vol 41 (4) ◽  
pp. 651-663
Author(s):  
N. R. Steenberg
Keyword(s):  
Cross Section ◽  
Spherical Geometry ◽  
Monte Carlo Study ◽  
Nuclear Data ◽  
High Energy ◽  
Rare Gas ◽  
Nuclear Radius ◽  
Rigid Spheres ◽  
High Energy Radiation ◽  
The Individual

The absorption of radiation in a spherical obstacle composed of rigid spheres has been studied. The result is the absorption cross section of such an obstacle as a function of the free cross section and the number A of the individual spheres and of packing density. It is found that the usual rare-gas formula represents the cross section adequately. The analysis is applied to nuclear data for the absorption of 25-Bev/c protons by nuclei. It is found that for a nuclear radius R = r0A1/3 + δ, where δ is the radius of the nucleon, r0 = 1.17 fermi, δ = 1.05 fermi, and an average nucleon transparency a2 = 0.30 is consistent with the data.

scholarly journals Exploring the bulk of the BL Lacertae object population

2018 ◽  
Vol 618 ◽  
pp. A175
Author(s):  
F. D’Ammando ◽  
M. Giroletti ◽  
S. Rainó
Keyword(s):  
Radio Emission ◽  
Test Statistic ◽  
Large Area ◽  
Bl Lacertae ◽  
The Third ◽  
Long Baseline ◽  
Photon Index ◽  
Multi Wavelength ◽  
Doppler Factor ◽  
Bl Lacs

Aims. We are studying an unbiased sample of 42 nearby (z < 0.2) BL Lacertae objects with a multi-wavelength approach. The results of Very Long Baseline Interferometry observations were presented in the first paper of this series. In this paper, we study the γ-ray properties of the sample. Methods. We analyse data collected by the Fermi-Large Area Telescope (LAT) during its first 8.5 yr of operation in the energy range 0.1−300 GeV. Results. We reveal 23 sources with a test statistic greater than 25 (corresponding to ~4.6-σ) out of 42, with 3 sources not detected in the third LAT active galactic nucleus (AGN) catalogue, and fluxes between 3.5 × 10−10 and 7.4 × 10−8 ph cm−2 s−1. The majority of the sources have hard spectra (Γ ≤ 2), with only four having values in the range 2.1–2.4. The three newly detected sources have fluxes in the range between 0.54 × 10−9 and 1.35 × 10−9 ph cm−2 s−1 and photon index 1.7–1.9. Among the 23 LAT-detected sources, 19 are included in the third catalogue of hard Fermi-LAT sources, with a spectrum that connects relatively smoothly from 0.1 GeV to 2 TeV. LAT-detected BL Lacs are more luminous on parsec scales with respect to non-LAT-detected sources and have larger core dominance according to the unified models. Conclusions. The LAT-detected BL Lacs seem to be composed of a bulk of “classical” sources dominated by Doppler boosting and characterised by compact and bright radio emission as well as hard γ-ray spectra. Moreover, we have identified a possible population of low-luminosity BL Lacs not detected by LAT, lacking a VLBI core, and with a small Doppler factor. Furthermore, three LAT-detected sources show non-classical properties for γ-ray emitting BL Lacs (no evidence of relativistic jet, low Doppler factor in radio images, relatively low core dominance) and three other sources, while showing radio emission on parsec scales, are not detected in γ rays so far.

scholarly journals Magnetar X-ray emission mechanisms

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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