This paper explores the correlation between the fractional variation of the ionizing continuum and CⅣbroad absorption lines(BALs)with different ionization levels.Our results reveal anti-correlations between fractiona...This paper explores the correlation between the fractional variation of the ionizing continuum and CⅣbroad absorption lines(BALs)with different ionization levels.Our results reveal anti-correlations between fractional variation of the continuum and fractional equivalency width(EW)variation of the CⅣB ALs without AlⅢB AL/mini-BALs at corresponding velocities,providing evidence for the widespread influence of the ionizing continuum variability on the variation of HiBALs.Conversely,for CⅣBALs accompanied by AlⅢBAL/mini-BALs(LoBAL groups),no significant correction is detected.The absence of such a correlation does not rule out the possibility that variations in these low-ionization lines are caused by ionizing continuum variability,but rather suggests the influence of B AL saturation to some extent.This saturation effect is reflected in the distribution of the fractional EW variation,where the CⅣBAL group accompanied by AlⅢBAL has a smaller standard deviation for the best-fitting Gaussian component than the two BAL groups without AlⅢB AL.However,the distribution of fractional variation of their continuum does not show any significant difference.Besides the saturation influence,another potential explanation for the lack of correlations in the LoBAL groups may be the effects of other variability mechanisms besides the ionization change,such as clouds transiting across the line of sight.展开更多
Fermi-LAT LCR provides continuous and regularly sampled gamma-ray light curves, spanning about 14 yr, for a large sample of blazars. The log-normal flux distribution and linear rms–flux relation of the light curves f...Fermi-LAT LCR provides continuous and regularly sampled gamma-ray light curves, spanning about 14 yr, for a large sample of blazars. The log-normal flux distribution and linear rms–flux relation of the light curves for a few Fermi blazars have been examined in previous studies. However, the probability that blazars exhibit the log-normal flux distribution and linear rms–flux relation in their gamma-ray light curves has not been systematically explored.In this study, we comprehensively research the distribution of γ-ray flux and the statistical characteristics on a large sample of 1414 variable blazars from the Fermi-LAT LCR catalog, including 572 FSRQs, 477 BL Lacs, and 365BCUs, and statistically compare their flux distributions with normal and log-normal distributions. The results indicate that the probability of not rejecting log-normal is 42.05% for the large sample, and there is still a 2.05%probability of not rejecting normality, based on the joint of Kolmogorov–Smirnov, Shapiro–Wilk, and Normality tests. We further find that the probability that BL Lacs conform to the log-normal distribution is higher than that of FSRQs. Besides, after removing sources with less than 200 data points from this large sample, a sample of 549blazars, which is still a large sample compared to the previous studies, was obtained. Based on dividing the light curves into segments every 20 points(or 40 points, or one year), we fitted the linear rms–flux relation of these three different sets and found that the Pearson correlation coefficients are all close to 1 for most blazars. This result indicates a strong linear correlation between the rms and the flux of these 549 blazars. The log-normal distribution and linear rms–flux relation indicate that the variability of the γ-ray flux for most blazars is a non-linear and multiplicative process.展开更多
From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectr...From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.展开更多
Quasars are very important in materializing the reference frame.The excess emission of active galactic nuclei(AGNs) in the mid-infrared band can be used to identify quasar candidates.As extremely distant and point-lik...Quasars are very important in materializing the reference frame.The excess emission of active galactic nuclei(AGNs) in the mid-infrared band can be used to identify quasar candidates.As extremely distant and point-like objects,quasars also could be further selected by an astrometry method.Increasing the number of reliable quasar candidates is necessary in characterizing the properties of Gaia astrometric solution and evaluating the reliability of Gaia’s own quasars classification.We identify quasars by using appropriate All WISE [W1-W2] color and different combinations of astrometric criteria.Together with the contamination and completeness,the magnitude,astrometric properties,density distribution,and the morphological indexes of these selected quasars are evaluated.We obtain a quasar candidate catalog of 1,503,373 sources,which contains 1,186,690 candidates(78.9%) in common with the Gaia EDR3_AGN catalog and 316,683 newly identified quasar candidates.The completeness of this catalog is around 80% compared to LQAC5,and the purity of the overall catalog is about 90%.We also found that the purity of quasar candidates selected by this method will decrease in the crowded sky area and the region with less WISE observations.展开更多
基金supported by the Guangxi Natural Science Foundation(No.2021GXNSFBA220044)the National Natural Science Foundation of China(No.11903002)the Research Project of Baise University(No.2019KN04)。
文摘This paper explores the correlation between the fractional variation of the ionizing continuum and CⅣbroad absorption lines(BALs)with different ionization levels.Our results reveal anti-correlations between fractional variation of the continuum and fractional equivalency width(EW)variation of the CⅣB ALs without AlⅢB AL/mini-BALs at corresponding velocities,providing evidence for the widespread influence of the ionizing continuum variability on the variation of HiBALs.Conversely,for CⅣBALs accompanied by AlⅢBAL/mini-BALs(LoBAL groups),no significant correction is detected.The absence of such a correlation does not rule out the possibility that variations in these low-ionization lines are caused by ionizing continuum variability,but rather suggests the influence of B AL saturation to some extent.This saturation effect is reflected in the distribution of the fractional EW variation,where the CⅣBAL group accompanied by AlⅢBAL has a smaller standard deviation for the best-fitting Gaussian component than the two BAL groups without AlⅢB AL.However,the distribution of fractional variation of their continuum does not show any significant difference.Besides the saturation influence,another potential explanation for the lack of correlations in the LoBAL groups may be the effects of other variability mechanisms besides the ionization change,such as clouds transiting across the line of sight.
基金funded by the National Natural Science Foundation of China (grants 12063007 and 11863007)。
文摘Fermi-LAT LCR provides continuous and regularly sampled gamma-ray light curves, spanning about 14 yr, for a large sample of blazars. The log-normal flux distribution and linear rms–flux relation of the light curves for a few Fermi blazars have been examined in previous studies. However, the probability that blazars exhibit the log-normal flux distribution and linear rms–flux relation in their gamma-ray light curves has not been systematically explored.In this study, we comprehensively research the distribution of γ-ray flux and the statistical characteristics on a large sample of 1414 variable blazars from the Fermi-LAT LCR catalog, including 572 FSRQs, 477 BL Lacs, and 365BCUs, and statistically compare their flux distributions with normal and log-normal distributions. The results indicate that the probability of not rejecting log-normal is 42.05% for the large sample, and there is still a 2.05%probability of not rejecting normality, based on the joint of Kolmogorov–Smirnov, Shapiro–Wilk, and Normality tests. We further find that the probability that BL Lacs conform to the log-normal distribution is higher than that of FSRQs. Besides, after removing sources with less than 200 data points from this large sample, a sample of 549blazars, which is still a large sample compared to the previous studies, was obtained. Based on dividing the light curves into segments every 20 points(or 40 points, or one year), we fitted the linear rms–flux relation of these three different sets and found that the Pearson correlation coefficients are all close to 1 for most blazars. This result indicates a strong linear correlation between the rms and the flux of these 549 blazars. The log-normal distribution and linear rms–flux relation indicate that the variability of the γ-ray flux for most blazars is a non-linear and multiplicative process.
基金provided by the National Development and Reform Commissionthe support of the National Natural Science Foundation of China(NSFC,11803004)+2 种基金Yunnan Province Youth Talent Project(2019182)the support by NSFC through grant No.12203011Yunnan provincial Department of Science and Technology through grant No.202101BA070001-261。
文摘From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.
基金supported by the Youth Innovation Promotion Association CAS with Certificate Number 2022259the grants from the Natural Science Foundation of Shanghai through grant 21ZR1474100+1 种基金the National Natural Science Foundation of China(NSFC)through grants 12173069,and 11703065the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-A12 and NO.CMS-CSST-2021-B10。
文摘Quasars are very important in materializing the reference frame.The excess emission of active galactic nuclei(AGNs) in the mid-infrared band can be used to identify quasar candidates.As extremely distant and point-like objects,quasars also could be further selected by an astrometry method.Increasing the number of reliable quasar candidates is necessary in characterizing the properties of Gaia astrometric solution and evaluating the reliability of Gaia’s own quasars classification.We identify quasars by using appropriate All WISE [W1-W2] color and different combinations of astrometric criteria.Together with the contamination and completeness,the magnitude,astrometric properties,density distribution,and the morphological indexes of these selected quasars are evaluated.We obtain a quasar candidate catalog of 1,503,373 sources,which contains 1,186,690 candidates(78.9%) in common with the Gaia EDR3_AGN catalog and 316,683 newly identified quasar candidates.The completeness of this catalog is around 80% compared to LQAC5,and the purity of the overall catalog is about 90%.We also found that the purity of quasar candidates selected by this method will decrease in the crowded sky area and the region with less WISE observations.
