A Relativistic Orbit Model for Temporal Properties of AGN

Rana, Prerna; Mangalam, A.

doi:10.3390/galaxies8030067

Cited by 3 publications

(1 citation statement)

References 69 publications

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“…Similarly, jet precession (Graham et al 2015), and jet precession induced in SMBBH can also result in periodic optical outbursts (Qian et al 2018;Caproni et al 2017). Moreover, in the case of strong gravitational fields, relativistic orbit models can be employed to explain the QPOs (see Rana & Mangalam 2020).…”

Section: • Optical Variability In Blazarsmentioning

confidence: 99%

Characterizing Long-term Optical Variability Properties of $γ$-ray Bright Blazars

Bhatta

2021

Preprint

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Optical observations of a sample of 12 γ-ray bright blazars from four optical data archives, AAVSO, SMARTS, Catalina, and Steward Observatory, are compiled to create densely sampled light curves spanning more than a decade. As a part of the blazar multi-wavelength studies, several methods of analyses, e. g., flux distribution and RMS-flux relation, are performed on the observations with an aim to compare the results with the similar ones in the γ-ray band presented in Bhatta & Dhital (2020). It is found that, similar to γ-ray band, blazars display significant variability in the optical band that can be characterized with log-normal flux distribution and a power-law dependence of RMS on flux. It could be an indication of possible inherent linear RMS-flux relation, yet the scatter in the data does not allow to rule out other possibilities. When comparing variability properties in the two bands, the blazars in the γ-rays are found to exhibit stronger variability with steeper possible linear RMS-flux relation and the flux distribution that is more skewed towards higher fluxes. The crosscorrelation study shows that except for the source 3C 273, the overall optical and the γ-ray emission in the sources are highly correlated, suggesting a co-spatial existence of the particles responsible for both the optical and γ-ray emission. Moreover, the sources S5 0716+714, Mrk 421, Mrk 501, PKS 1424-418 and PKS 2155-304 revealed possible evidence for quasi-periodic oscillations in the optical emission with the characteristic timescales, which are comparable to those in the γ-ray band detected in our previous work.

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Section: • Optical Variability In Blazarsmentioning

confidence: 99%

Characterizing Long-term Optical Variability Properties of $γ$-ray Bright Blazars

Bhatta

2021

Preprint

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A Geometric Origin for Quasi-periodic Oscillations in Black Hole X-Ray Binaries

Rana

Mangalam

2020

ApJ

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We expand the relativistic precession model to include nonequatorial and eccentric trajectories and apply it to quasi-periodic oscillations (QPOs) in black hole X-ray binaries (BHXRBs) and associate their frequencies with the fundamental frequencies of the general case of nonequatorial (with Carter's constant, ) and eccentric ( ) particle trajectories, around a Kerr black hole. We study cases with either two or three simultaneous QPOs and extract the parameters {e, r p , a, Q}, where r p is the periastron distance of the orbit, and a is the spin of the black hole. We find that the orbits with should have e ≲ 0.5 and r p ∼ 2–20 for the observed range of QPO frequencies, where a ∈ [0, 1], and that the spherical trajectories {e = 0, } with Q = 2–4 should have r s ∼ 3–20. We find nonequatorial eccentric solutions for both M82 X-1 and GROJ 1655-40. We see that these trajectories, when taken together, span a torus region and give rise to a strong QPO signal. For two simultaneous QPO cases, we found equatorial eccentric orbit solutions for XTEJ 1550-564, 4U 1630-47, and GRS 1915+105, and spherical orbit solutions for BHXRBs M82 X-1 and XTEJ 1550-564. We also show that the eccentric orbit solution fits the Psaltis–Belloni–Klis correlation observed in BHXRB GROJ 1655-40. Our analysis of the fluid flow in the relativistic disk edge suggests that instabilities cause QPOs to originate in the torus region. We also present some useful formulae for trajectories and frequencies of spherical and equatorial eccentric orbits.

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Characterizing Long-term Optical Variability Properties of γ-Ray-bright Blazars

Bhatta

2021

ApJ

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Optical observations of a sample of 12 γ-ray-bright blazars from four optical data archives—American Association of Variable Star Observers, Small and Moderate Aperture Research Telescope System, Catalina, and Steward Observatory—are compiled to create densely sampled light curves spanning more than a decade. As a part of the blazar multiwavelength studies, several methods of analysis, e.g., flux distribution and rms–flux relation, are performed on the observations with the aim to compare the results with the similar ones in the γ-ray band presented in Bhatta & Dhital. It is found that, similar to the γ-ray band, blazars display significant variability in the optical band that can be characterized with lognormal flux distribution and a power-law dependence of rms on flux. It could be an indication of a possible inherent linear rms–flux relation, yet the scatter in the data does not allow to rule out other possibilities. When comparing variability properties in the two bands, the blazars in the γ-rays are found to exhibit stronger variability with a steeper possible linear rms–flux relation and a flux distribution that is more skewed toward higher fluxes. The cross-correlation study shows that except for source 3C 273, the overall optical and the γ-ray emission in the sources are highly correlated, suggesting a cospatial existence of the particles responsible for both the optical and γ-ray emission. Moreover, sources S5 0716+714, Mrk 421, Mrk 501, PKS 1424-418, and PKS 2155-304 revealed possible evidence of quasiperiodic oscillations in the optical emission with the characteristic timescales, which are comparable to those in the γ-ray band detected in our previous work.

show abstract

A Relativistic Orbit Model for Temporal Properties of AGN

Cited by 3 publications

References 69 publications

Characterizing Long-term Optical Variability Properties of $γ$-ray Bright Blazars

Characterizing Long-term Optical Variability Properties of $γ$-ray Bright Blazars

A Geometric Origin for Quasi-periodic Oscillations in Black Hole X-Ray Binaries

Characterizing Long-term Optical Variability Properties of γ-Ray-bright Blazars

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