Spectral Variability of the X-Ray--bright BL Lacertae Object PKS 2005-489

1995 ◽  
Vol 449 ◽  
pp. 567 ◽  
Author(s):  
Rita M. Sambruna ◽  
C. Megan Urry ◽  
Gabriele Ghisellini ◽  
Laura Maraschi
Keyword(s):  
Spectral Variability ◽  
X Ray ◽  
Bl Lacertae

scholarly journals Temporal and Spectral Variability of OJ 287 before the April–June 2020 Outburst

Galaxies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 58
Author(s):  
Nibedita Kalita ◽  
Alok C. Gupta ◽  
Minfeng Gu
Keyword(s):  
Power Law ◽  
Lower Energy ◽  
X Rays ◽  
Power Law Model ◽  
Energy Bands ◽  
Spectral Variability ◽  
X Ray ◽  
Bl Lacertae ◽  
Inverse Compton ◽  
Absorbed Power

We present the results of a temporal and spectral study of the BL Lacertae object OJ 287 in optical, UV, and X-ray bands with observations performed by Swift satellite during September 2019–March 2020. In this period, the source showed moderate variability characterized by variability amplitude of ∼22–31% in all the wavelengths on a short timescale, except the hard X-ray band which was variable by only ∼8%. We observed that the X-ray flux of the source was significantly dominated by the soft photons below 2 keV. Soft lags of ∼45 days were detected between the optical/UV and soft X-ray emissions, while there is no correlation between the hard X-rays and the lower energy bands indicating the presence of two emission components or electron populations. Although two components contribute to the X-ray emission, most of the 0.3–10 keV spectra were well fitted with an absorbed power-law model which outlines the dominance of synchrotron over inverse Compton (IC) mechanism. The X-ray spectra follow a weak “softer when brighter” trend.

The X-ray spectral variability of the BL Lacertae type object PKS 2155-304

1993 ◽  
Vol 404 ◽  
pp. 112 ◽  
Author(s):  
S. Sembay ◽  
R. S. Warwick ◽  
C. M. Urry ◽  
J. Sokoloski ◽  
I. M. George ◽  
...  
Keyword(s):  
Spectral Variability ◽  
X Ray ◽  
Bl Lacertae ◽  
Type Object

X‐Ray Spectral Variability Signatures of Flares in BL Lacertae Objects

2002 ◽  
Vol 581 (1) ◽  
pp. 127-142 ◽  
Author(s):  
Markus Bottcher ◽  
James Chiang
Keyword(s):  
Spectral Variability ◽  
Bl Lacertae Objects ◽  
X Ray ◽  
Bl Lacertae

MICROVARIABILITY OF 0.3-10 keV FLUX IN HBL SOURCE PKS 2155-304

2014 ◽  
Vol 28 ◽  
pp. 1460179
Author(s):  
BIDZINA KAPANADZE ◽  
SERGO KAPANADZE ◽  
MANANA VARDOSANIDZE
Keyword(s):  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Parabolic Model ◽  
Spectral Variability ◽  
Complex Character ◽  
Single Observation ◽  
X Ray ◽  
Bl Lacertae ◽  
Curvature Parameter

The high energy peaked BL Lacertae object PKS 2155-304 has been observed 106-times by the X-ray Telescope onboard the Swift satellite through the 0.3-10 keV band since 2005 November 17. Among these observations, we have revealed 19 cases of the intraday flux variability at 99.9% confidence level with fractional rms amplitudes up to 30% and timescales ranging from 40 ks down to 0.4 ks. Flux changes were often accompanied by a spectral variability which showed a complex character in the presence of both clockwise and counter-clockwise evolution in a hardness ratio-flux plane. These events show rather curved spectra fitted well with the log-parabolic model. The curvature parameter ranged from 0.13 to 0.73 and showed different values for the spectra corresponding to the separate orbits of a single observation. The peak of spectral energy distribution ranged between 1.76 keV and 2.67 keV and generally was variable during the intraday flux changes. The soft and hard X-ray fluxes showed a strong correlation to each other. No correlation between the occurrence of intraday variations and source brightness state was seen — they are found as in flaring as well for intermediate and low states. The X-ray microvariability in PKS 2155-304 can be explained both with the shock-in-jet scenario and emergence of a "blob" of very energetic particles in the jet base.

scholarly journals X‐Ray Spectral Variability of Extreme BL Lacertae Active Galactic Nucleus H1426+428

2004 ◽  
Vol 601 (1) ◽  
pp. 165-172 ◽  
Author(s):  
A. D. Falcone ◽  
W. Cui ◽  
J. P. Finley
Keyword(s):  
Active Galactic Nucleus ◽  
Spectral Variability ◽  
X Ray ◽  
Bl Lacertae

scholarly journals X-RAY FLUX AND SPECTRAL VARIABILITY OF BL LACERTAE OBJECTS MRK 421, MRK 501, AND 1ES1426+428 WITH SUZAKU SATELLITE

2021 ◽  
Vol 57 (1) ◽  
pp. 133-145
Author(s):  
A. Ata Saad ◽  
Ahmed M. Nasser ◽  
Ahmed M. Abdelbar ◽  
M. M Beheary
Keyword(s):  
Spectral Study ◽  
Spectral Variability ◽  
F Test ◽  
Bl Lacertae Objects ◽  
X Ray ◽  
Bl Lacertae ◽  
Flux Variability

We present a detailed spectral study of Suzaku observations of three blazars (Mrk 421, Mrk 501, and 1ES1426+428). The X-ray properties of our sample are derived by extracting the BL Lacertae sample spectra, and fitted by five models. The fit was in the soft X-ray band (0.8 - 10.0 keV). These models give similar results. By comparing the fits from the different models, we find that the (zbremss+zpowerlw) model is the best one to represent the data. An F-test is applied to compare the (zbremss+zpowerlw) model with the simple one zpower law. To test the X-ray variability of our BL Lacertae sample, we fit their spectra extracted from the same instrument with the same procedure by the same model to estimate their X-ray flux and luminosity. The estimated fluxes are compared to check their variability. We find that the flux variability ranges are 3.06, 0.12, 0.37 × 10−10 erg s−1 cm−2 for Mrk 421, Mrk 501, and 1ES1426+428, respectively.

X‐Ray Absorption in the BL Lacertae Object PKS 0548−322

1998 ◽  
Vol 502 (2) ◽  
pp. 630-639 ◽  
Author(s):  
Rita M. Sambruna ◽  
Richard F. Mushotzky
Keyword(s):  
X Ray ◽  
Bl Lacertae ◽  
X Ray Absorption

scholarly journals The nature of X-ray spectral variability in SWIFT J2127.4+5654

2018 ◽  
Vol 480 (3) ◽  
pp. 3412-3423
Author(s):  
E S Kammoun ◽  
I E Papadakis
Keyword(s):  
Spectral Variability ◽  
X Ray

scholarly journals Longterm optical monitoring of bright BL Lacertae objects with ATOM: Spectral variability and multiwavelength correlations

2014 ◽  
Vol 573 ◽  
pp. A69 ◽  
Author(s):  
Alicja Wierzcholska ◽  
Michał Ostrowski ◽  
Łukasz Stawarz ◽  
Stefan Wagner ◽  
Marcus Hauser
Keyword(s):  
Optical Monitoring ◽  
Spectral Variability ◽  
Bl Lacertae Objects ◽  
Bl Lacertae

scholarly journals The intraday variability in the radio-selected and X-ray-selected BL Lacertae objects

1998 ◽  
Vol 132 (1) ◽  
pp. 83-92 ◽  
Author(s):  
J. M. Bai ◽  
G. Z. Xie ◽  
K. H. Li ◽  
X. Zhang ◽  
W. W. Liu
Keyword(s):  
Bl Lacertae Objects ◽  
X Ray ◽  
Bl Lacertae ◽  
Intraday Variability
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