scholarly journals X-ray spectra, light-curves and SEDs of blazars frequently observed by Swift

2021 ◽  
Author(s):  
Paolo Giommi ◽  
M Perri ◽  
M Capalbi ◽  
V D’Elia ◽  
U Barres de Almeida ◽  
...  
Keyword(s):  
Broad Band ◽  
Spectral Energy ◽  
Data Sets ◽  
Energy Bands ◽  
Energy Distributions ◽  
X Ray ◽  
Peak Energy ◽  
Parameter Values ◽  
Best Fit

Abstract Blazars research is one of the hot topics of contemporary extragalactic astrophysics. That is because these sources are the most abundant type of extragalactic γ-ray sources and are suspected to play a central role in multi-messenger astrophysics. We have used swift$\_$xrtproc, a tool to carry out an accurate spectral and photometric analysis of the Swift-XRT data of all blazars observed by Swift at least 50 times between December 2004 and the end of 2020. We present a database of X-ray spectra, best-fit parameter values, count-rates and flux estimations in several energy bands of over 31,000 X-ray observations and single snapshots of 65 blazars. The results of the X-ray analysis have been combined with other multi-frequency archival data to assemble the broad-band Spectral Energy Distributions (SEDs) and the long-term lightcurves of all sources in the sample. Our study shows that large X-ray luminosity variability on different timescales is present in all objects. Spectral changes are also frequently observed with a “harder-when-brighter” or “softer-when-brighter” behaviour depending on the SED type of the blazars. The peak energy of the synchrotron component (νpeak) in the SED of HBL blazars, estimated from the log-parabolic shape of their X-ray spectra, also exhibits very large changes in the same source, spanning a range of over two orders of magnitude in Mrk421 and Mrk501, the objects with the best data sets in our sample.

scholarly journals Broadband study of blazar 1ES 1959+650 during flaring state in 2016

2018 ◽  
Vol 611 ◽  
pp. A44 ◽  
Author(s):  
S. R. Patel ◽  
A. Shukla ◽  
V. R. Chitnis ◽  
D. Dorner ◽  
K. Mannheim ◽  
...  
Keyword(s):  
High Energy ◽  
Spectral Energy ◽  
Quiescent State ◽  
Energy Bands ◽  
Energy Distributions ◽  
X Ray ◽  
Broadband Emission ◽  
June July ◽  
Power Law Index ◽  
Observation Period

Aims. The nearby TeV blazar 1ES 1959+650 (z = 0.047) was reported to be in flaring state during June–July 2016 by Fermi-LAT, FACT, MAGIC and VERITAS collaborations. We studied the spectral energy distributions (SEDs) in different states of the flare during MJD 57530–57589 using simultaneous multiwaveband data with the aim of understanding the possible broadband emission scenario during the flare. Methods. The UV-optical and X-ray data from UVOT and XRT respectively on board Swift and high energy γ-ray data from Fermi-LAT were used to generate multiwaveband lightcurves as well as to obtain high flux states and quiescent state SEDs. The correlation and lag between different energy bands was quantified using discrete correlation function. The synchrotron self-Compton (SSC) model was used to reproduce the observed SEDs during flaring and quiescent states of the source. Results. A good correlation is seen between X-ray and high energy γ-ray fluxes. The spectral hardening with increase in the flux is seen in X-ray band. The power law index vs. flux plot in γ-ray band indicates the different emission regions for 0.1–3 GeV and 3–300 GeV energy photons. Two zone SSC model satisfactorily fits the observed broadband SEDs. The inner zone is mainly responsible for producing synchrotron peak and high energy γ-ray part of the SED in all states. The second zone is mainly required to produce less variable optical-UV and low energy γ-ray emission. Conclusions. Conventional single zone SSC model does not satisfactorily explain broadband emission during observation period considered. There is an indication of two emission zones in the jet which are responsible for producing broadband emission from optical to high energy γ-rays.

scholarly journals Eclipses of jets and discs of X-ray binaries as a powerful tool for understanding jet physics and binary parameters

2020 ◽  
Vol 499 (1) ◽  
pp. 957-973
Author(s):  
Thomas J Maccarone ◽  
Jakob van den Eijnden ◽  
Thomas D Russell ◽  
Nathalie Degenaar
Keyword(s):  
Jet Physics ◽  
Spectral Energy ◽  
Data Sets ◽  
Energy Distributions ◽  
X Ray ◽  
Orbital Parameters ◽  
Promising Target ◽  
Inclination Angles ◽  
Radio Band ◽  
X Ray Binaries

ABSTRACT We calculate the expected effects on the spectral energy distributions and light curves in X-ray binary jets from eclipses by the donor stars. Jets will be eclipsed for all inclination angles, with just the height along the jet where the eclipse takes place being set by the orbital parameters. Typically, eclipses will lead to 5–10 per cent reductions in the jet emission over a range of a factor of few in wavelength with a periodic modulation. In ideal systems with high inclination angles, relatively even mass ratios, and modest jet speeds, the eclipses may be deeper. We discuss how eclipses can be used to measure binary system parameters, as well as the height of the bases of the jets. We also discuss how, with data sets that will likely require future facilities, more detailed tests of models of jet physics could be made by establishing deviations from the standard recipes for compact conical flat spectrum jets and by determining the ingress and egress durations of the eclipses and measuring the transverse size of the jets. We provide representative calculations of expectations for different classes of systems, demonstrating that the most promising target for showing this effect in the radio band is the longer period ‘atoll’-class neutron star X-ray binaries, while in the optical and infrared bands, the best candidates are likely to be the most edge-on black hole X-ray binaries. We also discuss the effects of the outer accretion disc eclipsing the inner jet.

scholarly journals MWA and ASKAP observations of atypical radio-halo-hosting galaxy clusters: Abell 141 and Abell 3404

2021 ◽  
Vol 38 ◽  
Author(s):  
S. W. Duchesne ◽  
M. Johnston-Hollitt ◽  
A. G. Wilber
Keyword(s):  
Surface Brightness ◽  
Spectral Energy ◽  
Energy Distributions ◽  
X Ray ◽  
Radio Halo ◽  
Spectrum Radio ◽  
Murchison Widefield Array ◽  
Best Fit ◽  
Compact Array ◽  
Radio Halos

Abstract We report on the detection of a giant radio halo in the cluster Abell 3404 as well as confirmation of the radio halo observed in Abell 141 (with linear extents $\sim\!770$ and $\sim\!850$ kpc, respectively). We use the Murchison Widefield Array, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to characterise the emission and intervening radio sources from $\sim100$ to 1 000 MHz; power law models are fit to the spectral energy distributions with spectral indices $\alpha_{88}^{1\,110} = -1.66 \pm 0.07$ and $\alpha_{88}^{943} = -1.06 \pm 0.09$ for the radio halos in Abell 3404 and Abell 141, respectively. We find strong correlation between radio and X-ray surface brightness for Abell 3404 but little correlation for Abell 141. We note that each cluster has an atypical morphology for a radio-halo-hosting cluster, with Abell 141 having been previously reported to be in a pre-merging state, and Abell 3404 is largely relaxed with only minor evidence for a disturbed morphology. We find that the radio halo powers are consistent with the current radio halo sample and $P_\nu$ –M scaling relations, but note that the radio halo in Abell 3404 is an ultra-steep–spectrum radio halo (USSRH) and, as with other USSRHs lies slightly below the best-fit $P_{1.4}$ –M relation. We find that an updated scaling relation is consistent with previous results and shifting the frequency to 150 MHz does not significantly alter the best-fit relations with a sample of 86 radio halos. We suggest that the USSRH halo in Abell 3404 represents the faint class of radio halos that will be found in clusters undergoing weak mergers.

scholarly journals Project MOMO: Multiwavelength Observations and Modeling of OJ 287

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 261
Author(s):  
S. Komossa ◽  
D. Grupe ◽  
A. Kraus ◽  
L. C. Gallo ◽  
A. G. Gonzalez ◽  
...  
Keyword(s):  
Black Hole ◽  
Broad Band ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Binary Black Hole ◽  
Accretion Physics ◽  
Radio Measurements ◽  
Multiwavelength Observations

Our project MOMO (Multiwavelength observations and modeling of OJ 287) consists of dedicated, dense, long-term flux and spectroscopic monitoring, and deep follow-up observations of the blazar OJ 287 at >13 frequencies from the radio to the X-ray band since late 2015. In particular, we are using Swift to obtain optical-UV-X-ray spectral energy distributions (SEDs) and the Effelsberg telescope to obtain radio measurements between 2 and 40 GHz. MOMO is the densest long-term monitoring of OJ 287 involving X-rays and broad-band SEDs. The theoretical part of the project aims at understanding jet and accretion physics of the blazar central engine in general and the supermassive binary black hole scenario in particular. Results are presented in a sequence of publications and so far included: detection and detailed analysis of the bright 2016/17 and 2020 outbursts and the long-term light curve; Swift, XMM, and NuSTAR spectroscopy of the 2020 outburst around maximum; and interpretation of selected events in the context of the binary black hole scenario of OJ 287 (papers I–IV). Here, we provide a description of the project MOMO, a summary of previous results, the latest results, and we discuss future prospects.

scholarly journals Molecular Envelopes of Planetary Nebulae and Proto-Planetary Nebulae

1994 ◽  
Vol 140 ◽  
pp. 152-153
Author(s):  
Sun Kwok
Keyword(s):  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
High Rate ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model ◽  
Energy Distributions ◽  
Cool Component ◽  
Dust Envelope ◽  
Peak Energy

As stars evolve up the asymptotic giant branch (AGB), they begin to lose mass at a high rate, and in the process they create extended circumstellar molecular envelopes. Since the transition from AGB to planetary nebula stages is of the order of 1000 yr, the remnant of such molecular envelopes should still be observable in pro to-planetary nebulae (PPN) and planetary nebulae (PN). Recent ground-based survey of cool IRAS sources have discovered ~30 candidates of PPN (Kwok 1992). These sources show the characteristic “double-peak” energy distribution. The cool component is due to the remnant of the AGB dust envelope, and the hot component represents the reddened photosphere. The fact that the two components are clearly separated suggests that the dust envelope is well detached from the photosphere. Radiative transfer model fits to the spectral energy distributions of PPN suggest a typical separation of ~1 arc sec between the dust envelope and the photosphere, and such “hole-in-the-middle” structure can be mapped by millimeter interferometry in CO.

scholarly journals The Far‐Infrared Spectral Energy Distributions of X‐Ray–selected Active Galaxies

2003 ◽  
Vol 590 (1) ◽  
pp. 128-148 ◽  
Author(s):  
Joanna K. Kuraszkiewicz ◽  
Belinda J. Wilkes ◽  
Eric ◽  
J. Hooper ◽  
Kim K. McLeod ◽  
...  
Keyword(s):  
Far Infrared ◽  
Active Galaxies ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Infrared Spectral

scholarly journals The spectral energy distributions of active galactic nuclei

2019 ◽  
Vol 15 (S341) ◽  
pp. 21-25
Author(s):  
M. J. I. Brown ◽  
K. J. Duncan ◽  
H. Landt ◽  
M. Kirk ◽  
C. Ricci ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Wide Field ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Photometric Redshifts ◽  
X Ray ◽  
Ongoing Work ◽  
Prior Literature

AbstarctWe present ongoing work on the spectral energy distributions (SEDs) of active galactic nuclei (AGNs), derived from X-ray, ultraviolet, optical, infrared and radio photometry and spectroscopy. Our work is motivated by new wide-field imaging surveys that will identify vast numbers of AGNs, and by the need to benchmark AGN SED fitting codes. We have constructed 41 SEDs of individual AGNs and 80 additional SEDs that mimic Seyfert spectra. All of our SEDs span 0.09 to 30μm, while some extend into the X-ray and/or radio. We have tested the utility of the SEDs by using them to generate AGN photometric redshifts, and they outperform SEDs from the prior literature, including reduced redshift errors and flux density residuals.

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.

scholarly journals Identifications of Faint IRAS Sources

1996 ◽  
Vol 171 ◽  
pp. 402-402
Author(s):  
M.W. Kümmel ◽  
S.J. Wagner
Keyword(s):  
Broad Band ◽  
Far Infrared ◽  
Power Laws ◽  
Point Sources ◽  
Spectral Energy ◽  
Energy Distributions ◽  
The North ◽  
Luminosity Functions ◽  
Error Circle ◽  
Radio Band

From overlapping scans in the IRAS all-sky survey and additional pointed observations the deepest far infrared survey before ISO exists in the region around the North Ecliptic Pole (NEP) (Hacking P. and Houck J.R., ApJS 63 p. 311). This survey contains detections up to 10 and fluxes up to 100 times fainter than the IRAS survey. In the central square degree around the NEP we combine the far IR-survey with deep radio data at 151 MHz and 1.5 GHz (Visser, A.E. et al., A&AS 110 p. 419, Kollgaard, R.I. et al., ApJS 93 p. 145) and own observation at 2.2μm (K′) and 435nm (B). The error circle around the IRAS source was chosen to include the true source with 85% probability (1.4 sigma). For 29 of the 32 IRAS sources we found at least one possible counterpart. Ten of the objects have multiple (up to four) counterparts in K′. Four of the IRAS sources have counterparts in the 1.5 GHz survey. The higher accuracy of the radio position (∼ 1″) allowed an unambiguous identification of the K′ counterpart. None of the IRAS sources could be found in the 151 MHz survey. The broad band spectra of the three galaxies with measured radio flux exhibit maximum emission between the radio band and 100μm which corresponds to emission by cool dust (< 50 K). Contrary to the infrared luminosity functions at 12μm and 60μm which show power laws, the K′ luminosity function is bimodal. The brightest K′ objects are all point sources. Due to the small number statistics the power law indices of the luminosity functions can not be distinguished. We find a linear relationship between the K′ flux and the flux at 60μm and 12μm over at least one decade. The large deviations by individual sources make an identification of the correct counterpart through this relation impossible. The spectral energy distributions of unambiguously identified sources span only one decade in energy (vSv), i.e. they have flat energy distributions. This suggests an identification of K′ objects with flat energy distribution in case of multiple counterparts.

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

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 (&gt;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 &gt;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 (&lt;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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