In this work,we report for the first time two repeated quasi-periodic oscillations(QPOs)in the light curve of the Flat Spectrum Radio Quasar S51044+71.This source was observed by the Transiting Exoplanet Survey Satell...In this work,we report for the first time two repeated quasi-periodic oscillations(QPOs)in the light curve of the Flat Spectrum Radio Quasar S51044+71.This source was observed by the Transiting Exoplanet Survey Satellite in multiple sectors.We used the generalized Lomb-Scargle periodogram method and weighted wavelet Z-transform method to search for significant periodic signals.The main results are as follows:We found QPOs of~7.0 days(persisted for 4 cycles,with a significance of~3.5σ)and~7.3 days(persisted for 5 cycles,with a significance of~3.8σ)in the light curves of Sector 47 and EP1,respectively.Considering range of error,we regard them to be the same.We discussed two likely models of these rapid quasi-periodic variations:One comes from the jet and the other from the accretion disk.For the first one,we consider kink instability of the jet as a plausible explanation.Second,the QPO probably comes from the main hot spots in the accretion disk,which are located approximately within the innermost stable circular orbit allowed by general relativity.Based on this model,we estimate the mass of the black hole in S51044+71 to be 3.49×10^(9)M☉.展开更多
We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the...We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the Third LAT AGN Catalog. We performed standard unbinned maximum likelihood analysis on the LAT data during the period between August 2008 and December 2016, in order to obtain the average monthly flux. After quality cuts, blazars for which at least 90% of the total flux had survived were selected for further study, and this included 19 FSRQs and 19 BL Lacs. The Anderson-Darling and χ2 tests suggest that the integrated monthly flux follows a log-normal distribution for all sources, except for three FSRQs for which neither a normal nor a log-normal distribution was preferred. A double log-normal flux distribution tendency was observed in these sources, though this has to be confirmed with improved statistics. We also found that the standard deviation of the log-normal flux distribution increases with the mean spectral index of the blazar, and can be fitted with a line of slope 0.24±0.04. We repeat our study on three additional brightest unclassified blazars to identify their flux distribution properties. Based on the features of their log-normal flux distribution, we infer these unclassified blazars may be closely associated with FSRQs. We also highlight that considering the lognormal behavior of the flux distribution of blazars, averaging their long term flux on a linear scale can largely underestimate the nominal flux and this discrepancy can propagate down to the estimation of source parameters through spectral modeling.展开更多
The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation ...The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.12203041,12063007,and 11863007)Yunnan Province China-Malaysia HF-VHF Advanced Radio Astronomy Technology International Joint Laboratory(No.202303AP140003)。
文摘In this work,we report for the first time two repeated quasi-periodic oscillations(QPOs)in the light curve of the Flat Spectrum Radio Quasar S51044+71.This source was observed by the Transiting Exoplanet Survey Satellite in multiple sectors.We used the generalized Lomb-Scargle periodogram method and weighted wavelet Z-transform method to search for significant periodic signals.The main results are as follows:We found QPOs of~7.0 days(persisted for 4 cycles,with a significance of~3.5σ)and~7.3 days(persisted for 5 cycles,with a significance of~3.8σ)in the light curves of Sector 47 and EP1,respectively.Considering range of error,we regard them to be the same.We discussed two likely models of these rapid quasi-periodic variations:One comes from the jet and the other from the accretion disk.For the first one,we consider kink instability of the jet as a plausible explanation.Second,the QPO probably comes from the main hot spots in the accretion disk,which are located approximately within the innermost stable circular orbit allowed by general relativity.Based on this model,we estimate the mass of the black hole in S51044+71 to be 3.49×10^(9)M☉.
基金This work is supported by the National 973 project (NKBRSF G19990754)the National Science Fund for Distinguished YoungScholars (10125313)+1 种基金the Fundfor Top Scholars of Guangdong Provience (Q02114)This research has made use of data fromthe University of Michigan Radio Astronomy Observatory which has been supported by the University of Michigan and the National Science Foundation
基金the Indian Space Research Organization program(ISRO-RESPOND)for the financial support(Grant No.ISRO/RES/2/396)
文摘We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the Third LAT AGN Catalog. We performed standard unbinned maximum likelihood analysis on the LAT data during the period between August 2008 and December 2016, in order to obtain the average monthly flux. After quality cuts, blazars for which at least 90% of the total flux had survived were selected for further study, and this included 19 FSRQs and 19 BL Lacs. The Anderson-Darling and χ2 tests suggest that the integrated monthly flux follows a log-normal distribution for all sources, except for three FSRQs for which neither a normal nor a log-normal distribution was preferred. A double log-normal flux distribution tendency was observed in these sources, though this has to be confirmed with improved statistics. We also found that the standard deviation of the log-normal flux distribution increases with the mean spectral index of the blazar, and can be fitted with a line of slope 0.24±0.04. We repeat our study on three additional brightest unclassified blazars to identify their flux distribution properties. Based on the features of their log-normal flux distribution, we infer these unclassified blazars may be closely associated with FSRQs. We also highlight that considering the lognormal behavior of the flux distribution of blazars, averaging their long term flux on a linear scale can largely underestimate the nominal flux and this discrepancy can propagate down to the estimation of source parameters through spectral modeling.
基金was partially supported by the National Natural Science Foundation of China (Grant Nos. 10573005 and 10633010)the National Basic Research Program of China (Grant No. 2007CB815405)the Fund of the 11th Five-year Plan for Key Construction Academic Subject (Optics) of Hunan Province
文摘The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.
