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

A. D. Falcone; W. Cui; J. P. Finley

doi:10.1086/380447

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

The Astrophysical Journal ◽

10.1086/176080 ◽

1995 ◽

Vol 449 ◽

pp. 567 ◽

Cited By ~ 18

Author(s):

Rita M. Sambruna ◽

C. Megan Urry ◽

Gabriele Ghisellini ◽

Laura Maraschi

Keyword(s):

Spectral Variability ◽

X Ray ◽

Bl Lacertae

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

Galaxies ◽

10.3390/galaxies8030058 ◽

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.

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

The Astrophysical Journal ◽

10.1086/172263 ◽

1993 ◽

Vol 404 ◽

pp. 112 ◽

Cited By ~ 59

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

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

The Astrophysical Journal ◽

10.1086/344155 ◽

2002 ◽

Vol 581 (1) ◽

pp. 127-142 ◽

Cited By ~ 131

Author(s):

Markus Bottcher ◽

James Chiang

Keyword(s):

Spectral Variability ◽

Bl Lacertae Objects ◽

X Ray ◽

Bl Lacertae

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

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514601793 ◽

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.

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

Revista Mexicana de Astronomía y Astrofísica ◽

10.22201/ia.01851101p.2021.57.01.09 ◽

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.

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

The Astrophysical Journal ◽

10.1086/305922 ◽

1998 ◽

Vol 502 (2) ◽

pp. 630-639 ◽

Cited By ~ 12

Author(s):

Rita M. Sambruna ◽

Richard F. Mushotzky

Keyword(s):

X Ray ◽

Bl Lacertae ◽

X Ray Absorption

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Exploring the X-ray universe via timing: mass of the active galactic nucleus black hole XMMUJ134736.6+173403

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003312 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 348-350

Author(s):

Eva Šrámková ◽

K. Goluchová ◽

G. Török ◽

Marek A. Abramowicz ◽

Z. Stuchlík ◽

...

Keyword(s):

Black Hole ◽

Frequency Ratio ◽

Active Galactic Nucleus ◽

Periodic Modulation ◽

X Ray ◽

Upper Limit ◽

M 10 ◽

Frequency Ratios ◽

Quasiperiodic Oscillations ◽

Twin Peak

AbstractA strong quasi-periodic modulation has recently been revealed in the X-ray flux of the X-ray source XMMUJ134736.6+173403. The two observed twin-peak quasiperiodic oscillations (QPOs) exhibit a 3:1 frequency ratio and strongly support the evidence for the presence of an active galactic nucleus black hole (AGN BH). It has been suggested that detections of twin-peak QPOs with commensurable frequency ratios and scaling of their periods with BH mass could provide the basis for a method intended to determine the mass of BH sources, such as AGNs. Assuming the orbital origin of QPOs, we calculate the upper and lower limit on the AGN BH mass M, reaching M ≍ 107–109M⊙. Compared to mass estimates of other sources, XMMUJ134736.6+173403 appears to be the most massive source with commensurable QPO frequencies, and its mass represents the current observational upper limit on the AGN BH mass obtained from the QPO observations.

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