Constraints on Black Hole Masses With Timescales of Variations in Blazars

Abstract

In this paper, we investigated the issue of black hole masses and minimum timescales of jet emission for blazars. We proposed a sophisticated model that sets an upper limit to the central black hole masses M • with the minimum timescales Δt min ob of variations observed in blazars. The value of Δt min ob presents an upper limit to the size of the blob in the jet. The blob is assumed to be generated in the jet-production region in the vicinity of the black hole, and then the expanding blob travels outward along the jet. We applied the model to 32 blazars, 29 of which were detected in gamma-rays by satellites, and these Δt min ob are on the order of hours, with large variability amplitudes. In general, the M • estimated with this method are not inconsistent with those masses reported in the literature. This model is natural for connecting M • with Δt min ob for blazars, and seems to be applicable in constraining M • in the central engines of blazars.

The flat-spectrum radio quasar 3C 345 from the high to the low emission state

“…The black hole mass of 3C 345 has been calculated several times in the literature, with values spanning between 10 6 M ⊙ (Zhang et al 1998) to the much higher estimate provided by Lobanov & Roland (2005) of two black holes of 7×10 8 M ⊙ each. Our estimate is however in good agreement with the upper limit provided by Liu & Bai (2015) and derived through the γ-ray variability timescale (log (M/M ⊙ ) = 9.10), and with those provided by Xie et al (2005) and Ghisellini et al (2014) (log (M/M ⊙ ) = 8.41, and 9.03, respectively).…”

Search for Intra-day Optical Variability in γ-Ray-loud Blazars S5 0716+714 and 3C 273

“…The close correlations between the flares of different bands indicate that the IDV is an intrinsic phenomenon (Wagner & Witzel 1995). Some models were proposed to study the underlying connections between the timescales of variations and the masses of black holes, M • (e.g., Abramowicz & Nobili 1982;Miller et al 1989;Xie et al 2002;Liu & Bai 2015). The observed minimum timescales, ∆t ob min , of variability were generally used to estimate M • for AGNs (e.g., Abramowicz & Nobili 1982;Miller et al 1989;Xie et al 2002Xie et al , 2005Dai et al 2015;Liu & Bai 2015).…”

“…Blazars show violent variability across the entire electromagnetic spectrum on different timescales from minutes to years. Timescales and amplitudes of variations, and shapes of light curves (LCs), could shed light on some intrinsic properties of blazars, e.g., the sizes of emission regions, the masses of black holes, and the radiation mechanism (e.g., Miller et al 1989;Xie et al 2002;Liu & Bai 2015;Guo et al 2016;Feng et al 2017;Li et al 2017;Xiong et al 2017;Yuan et al 2017). The variation timescales of blazars are divided into three classes.…”

“…Several models were proposed to explain the variability of blazars, such as the shock-in-jet model (Marscher & Gear 1985;Qian et al 1991) and the disk instability model (Kawaguchi et al 1998). The IDVs in blazars seem to be important since the IDV timescales are likely related to the central supermassive black boles in blazars (Liu & Bai 2015;Feng et al 2017). However, it is difficult to measure the masses of black holes in blazars due to the Doppler boosted emission from the jets of blazars.…”

Estudio observacional de la emisión óptica de blazares detectados a altas energías

“…Debido a las propiedades de fuerte variabilidad de los blazares, la foto-polarimetría es muy utilizada para investigar su estructura, mecanismos de radiación, dinámica y las masas de los SMBH (Ciprini et al 2003(Ciprini et al , 2007Gupta et al 2008; Barres de Almeida et Liu & Bai 2015;Dai et al 2015;Covino et al 2015). Sin embargo, es necesario tener presente que estos objetos están formados por dos estructuras bien marcadas y muy diferentes entre sí.…”