scholarly journals Variations of the physical parameters of the blazar Mrk 421 based on analysis of the spectral energy distributions

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Yurika Yamada ◽  
Makoto Uemura ◽  
Ryosuke Itoh ◽  
Yasushi Fukazawa ◽  
Masanori Ohno ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Optimal Solution ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Zone Model ◽  
Spectral Energy Distributions ◽  
Large Area ◽  
Energy Distributions ◽  
X Ray ◽  
The One

Abstract We report on the variations of the physical parameters of the jet observed in the blazar Mrk 421, and discuss the origin of X-ray flares in the jet, based on analysis of several spectral energy distributions (SEDs). The SEDs are modeled using the one-zone synchrotron self-Compton model, its parameters determined using a Markov chain Monte Carlo method. The lack of data at TeV energies means many of the parameters cannot be uniquely determined and are correlated. These are studied in detail. We find that the optimal solution can be uniquely determined only when we apply a constraint to one of four parameters: the magnetic field (B), the Doppler factor, the size of the emitting region, and the normalization factor of the electron energy distribution. We used 31 sets of SEDs from 2009 to 2014 with optical–UV data observed with UVOT/Swift and the Kanata telescope, X-ray data with XRT/Swift, and γ-ray data with the Fermi Large Area Telescope. The result of our SED analysis suggests that, in the X-ray faint state, the emission occurs in a relatively small area (∼1016 cm) with a relatively strong magnetic field (B ∼ 10−1 G). The X-ray bright state shows a tendency opposite to that of the faint state, that is, a large emitting area (∼1018 cm), probably downstream of the jet, and a weak magnetic field (B ∼ 10−3 G). The high X-ray flux was due to an increase in the maximum energy of electrons. On the other hand, the presence of two kinds of emitting areas implies that the one-zone model is unsuitable for reproducing at least part of the observed SEDs.

scholarly journals Physical properties of the CDFS X-ray sources through fitting spectral energy distributions

2019 ◽  
Vol 492 (2) ◽  
pp. 1887-1901 ◽  
Author(s):  
Xiaotong Guo ◽  
Qiusheng Gu ◽  
Nan Ding ◽  
E Contini ◽  
Yongyun Chen
Keyword(s):  
Star Formation ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Type I ◽  
Type Ii ◽  
Host Galaxies ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Normal Galaxies

ABSTRACT The physical parameters of galaxies and/or active galactic nucleus (AGNs) can be derived by fitting their multiband spectral energy distributions (SEDs). By using cigale code, we perform multiband SED fitting (from ultraviolet to infrared) for 791 X-ray sources (518 AGNs and 273 normal galaxies) in the 7 Ms Chandra Deep Field-south survey (CDFS). We consider the contributions from AGNs and adopt more accurate redshifts than published before. Therefore, more accurate star formation rates (SFRs) and stellar masses (M*) are derived. We classify the 518 AGNs into type-I and type-II based on their optical spectra and their SEDs. Moreover, six AGN candidates are selected from the 273 normal galaxies based on their SEDs. Our main results are as follows: (1) the host galaxies of AGNs have larger M* than normal galaxies, implying that AGNs prefer to host in massive galaxies; (2) the specific star formation rates (sSFRs) of AGN host galaxies are different from those of normal galaxies, suggesting that AGN feedback may play an important role in the star formation activity; (3) we find that the fraction of optically obscured AGNs in CDFS decreases with the increase of intrinsic X-ray luminosity, which is consistent with previous studies; and (4) the host galaxies of type-I AGNs tend to have lower M* than type-II AGNs, which may suggest that dust in the host galaxy may also contribute to the optical obscuration of AGNs.

scholarly journals The Quasar Continuum

2009 ◽  
Vol 5 (S267) ◽  
pp. 55-64
Author(s):  
Martin Elvis
Keyword(s):  
Continuum Emission ◽  
Spectral Energy ◽  
Scaling Relations ◽  
Physical Parameters ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Wide Range

AbstractThe powerful compact continuum emission from quasars is understood only in outline. New surveys allow investigation of the quasar continuum over a wide range of parameters (z, L, L/LEdd) and wavelengths (radio to X-ray). I review the spectral energy distributions of quasars and how new scaling relations with physical parameters promise to take us to a deeper understanding of the quasar continuum.

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 The spectral energy distributions of the entire Herschel Reference Survey

2011 ◽  
Vol 7 (S284) ◽  
pp. 283-285
Author(s):  
Laure Ciesla ◽  
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Distant Galaxies ◽  
First Results ◽  
Nearby Galaxies ◽  
Stellar Masses

AbstractWe present the spectral energy distributions (SED) of the 323 galaxies of the Herschel Reference Survey. In order to provide templates for nearby galaxies calibrated on physical parameters, we computed mean SEDs per bin of morphological types and stellar masses. They will be very useful to study more distant galaxies and their evolution with redshift. This preliminary work aims to study how the most commonly used libraries (Chary & Elbaz 2001, Dale & Helou 2002 and Draine & Li 2007) reproduce the far-infrared emission of galaxies. First results show that they reproduce well the far-infrared part of mean SEDs. For single galaxies the Draine & Li (2007) models seem to reproduce very well the far-infrared emission, as does the Dale & Helou (2002).

Solar analogs: Spectral energy distributions and physical parameters of their atmospheres

2000 ◽  
Vol 44 (4) ◽  
pp. 246-254 ◽  
Author(s):  
I. N. Glushneva ◽  
V. I. Shenavrin ◽  
I. A. Roshchina
Keyword(s):  
Spectral Energy ◽  
Physical Parameters ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Solar Analogs

scholarly journals Infrared to x-ray spectral energy distributions of high redshift quasars

1994 ◽  
Vol 108 ◽  
pp. 374 ◽  
Author(s):  
Jill Bechtold ◽  
Martin Elvis ◽  
Fabrizio Fiore ◽  
Olga Kuhn ◽  
Roc M. Cutri ◽  
...  
Keyword(s):  
High Redshift ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray

scholarly journals Multiwavelength Energy Distributions of Ultraluminous IRAS Galaxies

1994 ◽  
Vol 159 ◽  
pp. 332-332
Author(s):  
D. Rigopoulou ◽  
A. Lawrence
Keyword(s):  
Energy Source ◽  
Star Formation ◽  
Active Galaxies ◽  
Spectral Energy ◽  
Published Data ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Space Density ◽  
X Ray

Ultraluminous IRAS Galaxies (ULG's) have luminosities comparable to quasars while their space density is much higher than that of active galaxies. Much debate has centered around the origin of the energy source for these objects, whether this is a burst of star formation or a hidden quasar. The sample studied here is the Sanders et al. (1988) sample, 10 objects with LFIR ≥ 1012L⊙. We discuss our new observations at X-ray and submm wavelengths together with other published data for some of the objects. Some useful ideas can be gained from comparisons of the shape of the spectral energy distributions (SED's) of the ultraluminous objects with other “archetype” objects such as typical starbursts i.e. M82 or type 2 AGN i.e. NGC1068.

scholarly journals The spectral energy distributions of active galactic nuclei

2019 ◽  
Vol 489 (3) ◽  
pp. 3351-3367 ◽  
Author(s):  
M J I Brown ◽  
K J Duncan ◽  
H Landt ◽  
M Kirk ◽  
C Ricci ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Flux Density ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Power Laws ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Photometric Redshifts ◽  
X Ray

ABSTRACT We present spectral energy distributions (SEDs) of 41 active galactic nuclei, derived from multiwavelength photometry and archival spectroscopy. All of the SEDs span at least 0.09 to 30 $\mu$m, but in some instances wavelength coverage extends into the X-ray, far-infrared, and radio. For some active galactic nuclei (AGNs) we have fitted the measured far-infrared photometry with greybody models, while radio flux density measurements have been approximated by power laws or polynomials. We have been able to fill some of the gaps in the spectral coverage using interpolation or extrapolation of simple models. In addition to the 41 individual AGN SEDs, we have produced 72 Seyfert SEDs by mixing SEDs of the central regions of Seyferts with galaxy SEDs. Relative to the literature, our templates have broader wavelength coverage and/or higher spectral resolution. We have tested the utility of our SEDs by using them to generate photometric redshifts for 0 < z ≤ 6.12 AGNs in the Boötes field (selected with X-ray, IR, and optical criteria) and, relative to SEDs from the literature, they produce comparable or better photometric redshifts with reduced flux density residuals.

scholarly journals HELP: modelling the spectral energy distributions of Herschel detected galaxies in the ELAIS N1 field

2018 ◽  
Vol 620 ◽  
pp. A50 ◽  
Author(s):  
K. Małek ◽  
V. Buat ◽  
Y. Roehlly ◽  
D. Burgarella ◽  
P. D. Hurley ◽  
...  
Keyword(s):  
Near Infrared ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Mass Star ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
The Impact ◽  
Attenuation Laws ◽  
Peculiar Galaxies

Aims. The Herschel Extragalactic Legacy Project (HELP) focuses on the data from ESA’s Herschel mission, which covered over 1300 deg2 and is preparing to publish a multi-wavelength catalogue of millions of objects. Our main goal is to find the best approach to simultaneously fitting spectral energy distributions (SEDs) of millions of galaxies across a wide redshift range to obtain homogeneous estimates of the main physical parameters of detected infrared (IR) galaxies. Methods. We perform SED fitting on the ultraviolet(UV)/near-infrared(NIR) to far-infrared(FIR) emission of 42 047 galaxies from the pilot HELP field: ELAIS N1. To do this we use the latest release of CIGALE, a galaxy SED fitting code relying on energy balance, to deliver the main physical parameters such as stellar mass, star formation rate, and dust luminosity. We implement additional quality criteria to the fits by calculating χ2 values for the stellar and dust part of the spectra independently. These criteria allow us to identify the best fits and to identify peculiar galaxies. We perform the SED fitting of ELAIS N1 galaxies by assuming three different dust attenuation laws separately allowing us to test the impact of the assumed law on estimated physical parameters. Results. We implemented two additional quality value checks for the SED fitting method based on stellar mass estimation and energy budget. This method allows us to identify possible objects with incorrect matching in the catalogue and peculiar galaxies; we found 351 possible candidates of lensed galaxies using two complementary χ2s criteria (stellar and infrared χ2s) and photometric redshifts calculated for the IR part of the spectrum only. We find that the attenuation law has an important impact on the stellar mass estimate (on average leading to disparities of a factor of two). We derive the relation between stellar mass estimates obtained by three different attenuation laws and we find the best recipe for our sample. We also make independent estimates of the total dust luminosity parameter from stellar emission by fitting the galaxies with and without IR data separately.

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