We present an analysis of the cross-correlation between optical brightness and polarization degree in different types of blazars.The aim is to identify objects with simultaneous and consistent changes in characteristi...We present an analysis of the cross-correlation between optical brightness and polarization degree in different types of blazars.The aim is to identify objects with simultaneous and consistent changes in characteristics and to determine if this behavior relates to the types of objects studied.The analysis includes 23 objects:11 Flat Spectrum Radio Quasars(FSRQs),11 BL Lacs,and 1 radio galaxy.Dense overlapping observation series in the R band were used,collected over more than 10 yr as part of a monitoring program for bright blazars at St.Petersburg State University.The cross-correlation analysis procedure is detailed,including a method for assessing significance based on Monte Carlo simulations of synthetic light curves modeled using a Damped Random Walk.Significant correlations were found for 5 FSRQs and 1 BL Lac.No significant correlation was detected for 10 BL Lacs and 6 FSRQs.One object did not yield a reliable estimate.Based on the current results,we cannot claim that the observed difference in the behavior of these emission characteristics for different classes of blazars is significant.It is possible that observed correlations may be explained by the contribution of simultaneous flare events to the changes in flux and polarization degree curves,which occur more frequently in FSRQs.展开更多
Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scen...Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scenario,jets inject energy into the polar ejecta,modifying its evolution and shaping the explosion geometry.This study investigates the polarization signatures of jet-driven bipolar explosions in SLSNe/LSNe,where the asymmetric ejecta structure and differential photospheric evolution imprint distinct observational features.We develop a two-component ejecta model,consisting of fast-expanding polar ejecta(powered by jets)and slower equatorial ejecta.We find that polarization exhibits complex temporal evolution,where the ejecta geometry and flux asymmetry between the two regions jointly produce a double-peaked feature.In addition,the line opacity in the polar region further enhances the wavelength dependence of the polarization.Spectropolarimetric observations,particularly during early phases,can constrain the geometry and energy sources of SLSNe/LSNe,advancing our understanding of their explosion mechanisms.展开更多
基金the National Science Foundation grant AST-2108622several NASA Fermi vip Investigator grants,the latest is 80NSSC23K1507supported by Fermi vip Investigator grants NNX08AW56G,NNX09AU10G,NNX12AO93G,and NNX15AU81G.
文摘We present an analysis of the cross-correlation between optical brightness and polarization degree in different types of blazars.The aim is to identify objects with simultaneous and consistent changes in characteristics and to determine if this behavior relates to the types of objects studied.The analysis includes 23 objects:11 Flat Spectrum Radio Quasars(FSRQs),11 BL Lacs,and 1 radio galaxy.Dense overlapping observation series in the R band were used,collected over more than 10 yr as part of a monitoring program for bright blazars at St.Petersburg State University.The cross-correlation analysis procedure is detailed,including a method for assessing significance based on Monte Carlo simulations of synthetic light curves modeled using a Damped Random Walk.Significant correlations were found for 5 FSRQs and 1 BL Lac.No significant correlation was detected for 10 BL Lacs and 6 FSRQs.One object did not yield a reliable estimate.Based on the current results,we cannot claim that the observed difference in the behavior of these emission characteristics for different classes of blazars is significant.It is possible that observed correlations may be explained by the contribution of simultaneous flare events to the changes in flux and polarization degree curves,which occur more frequently in FSRQs.
基金supported by the National Natural Science Foundation of China(Projects 12373040 and 12021003)the National SKA Program of China(2022SKA0130100)the Fundamental Research Funds for the Central Universities.
文摘Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scenario,jets inject energy into the polar ejecta,modifying its evolution and shaping the explosion geometry.This study investigates the polarization signatures of jet-driven bipolar explosions in SLSNe/LSNe,where the asymmetric ejecta structure and differential photospheric evolution imprint distinct observational features.We develop a two-component ejecta model,consisting of fast-expanding polar ejecta(powered by jets)and slower equatorial ejecta.We find that polarization exhibits complex temporal evolution,where the ejecta geometry and flux asymmetry between the two regions jointly produce a double-peaked feature.In addition,the line opacity in the polar region further enhances the wavelength dependence of the polarization.Spectropolarimetric observations,particularly during early phases,can constrain the geometry and energy sources of SLSNe/LSNe,advancing our understanding of their explosion mechanisms.
