We present the results of the multi-epoch broadband spectral study of 1ES 2344+514 and study the evolution of physical parameters.We used nearly simultaneous data obtained from 2017 June 6 to 2022 August 6(MJD 57910–...We present the results of the multi-epoch broadband spectral study of 1ES 2344+514 and study the evolution of physical parameters.We used nearly simultaneous data obtained from 2017 June 6 to 2022 August 6(MJD 57910–59797)in optical,UV,X-ray andγ-ray wavebands from various instruments including Swift-UVOT,Swift-XRT,Nuclear Spectroscopic Telescope Array(NuSTAR),AstroSat(SXT and LAXPC),Fermi-LAT,and TeV flux from MAGIC.During 2017 July,1ES 2344+514 appeared to be in the highest flaring state compared to other periods.We used the 0.5–7.0 keV and 3.0–20.0 keV data,respectively,from SXT and LAXPC of AstroSat and also 0.3–8.0 keV and 3.0–79.0 keV data,respectively,from Swift-XRT and NuSTAR.A joint fit between SXT and LAXPC,and between Swift-XRT and NuSTAR has been done for constraining the synchrotron peak.A clear shift in the synchrotron peak has been observed,which included 1ES 2344+514 in the HSP BL Lac family.A“harder-when-brighter”trend is observed in X-rays,and the opposite trend,i.e.,“softer-when-brighter,”is seen in theγ-rays.The multi-epoch broadband spectral energy distributions(SEDs)of this source were built and studied to get an idea of the radiation processes.The SEDs were fitted using a steady-state leptonic one-zone synchrotron+SSC model,and the fitted parameters of the emission region are consistent with those of other TeV BL Lacs.In this study,we found a weak correlation tendency between bolometric luminosity and magnetic field(B),as well as between bolometric luminosity and the break Lorentz factor(γ_(break)).展开更多
We analyzed the optical monitoring data in the R band of Te V blazar 1ES 1959+650 from 2002 to 2018,and provided evidence of a quasi-periodic oscillation in this object.The light curve shows a stable and persistent pe...We analyzed the optical monitoring data in the R band of Te V blazar 1ES 1959+650 from 2002 to 2018,and provided evidence of a quasi-periodic oscillation in this object.The light curve shows a stable and persistent periodicity at~540 days,detected by the Lomb–Scargle periodogram,Jurkevich and weighted wavelet z-transform techniques.The red noise power spectrum was estimated using the PSRESP method,and this period was found to be at>3σsignificance level.There are also two possible periodicities at~268 and~1100 days detected by all three methods.However,their significance levels are relatively low,and thus these two periods cannot be verified by the present data.We discuss several possible physical models that could explain the periodic variability in this object.展开更多
We here report a monitor of the BL Lac object 1 ES 1218+304 in both B-and R-bands by the GWAC-F60 A telescope in eight nights,when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory...We here report a monitor of the BL Lac object 1 ES 1218+304 in both B-and R-bands by the GWAC-F60 A telescope in eight nights,when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups.Both ANOVA and χ^(2)-test enable us to clearly reveal an intraday variability in optical wavelengths in seven out of the eight nights.A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights,which can be well explained by the shock-in-jet model.In addition,a quasi-periodic oscillation phenomenon in both bands could be tentatively identified in the first night.A positive delay between the two bands has been revealed in three out of the eight nights,and a negative one in the other nights.The identified minimum time delay enables us to estimate the MBH=2.8 × 10^(7) M_(⊙) that is invalid.展开更多
The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with th...The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with the Suzaku, MAGICand VERITAS telescopes, clearly reveal nonthermal power-law spectra. We study thebroadband nonthermal spectra of the two sources by using a combination of a one-zone homogeneous synchrotron self-Compton （SSC） model and an inhomogeneousconical jet model, where the new external background light （EBL） model is taken intoaccount. The results show that （1） the nonthermal emissions of the two blazars, rang-ing from X-rays to VHE γ-rays, are from the homogeneous zone whereas the emis-sions in the radio bands can be explained as the radiation from the inhomogeneousconical jet; （2） a strict lower-limit EBL model can be used to explain their observedspectra well.展开更多
Primary gamma rays emitted from extragalactic very-high-energy （VHE） sources, such as blazars, will generate cascade radiation in intergalactic space with a scale of -- 100 Mpc, for z - 0.1 and Eγ -1 TeV. These cas...Primary gamma rays emitted from extragalactic very-high-energy （VHE） sources, such as blazars, will generate cascade radiation in intergalactic space with a scale of -- 100 Mpc, for z - 0.1 and Eγ -1 TeV. These cascades proceed through electron-positron pair production and inverse Compton （IC） scattering in the cosmic background radiation fields, mainly cosmic microwave background （CMB） radiation and extragalactic background light in the voids of the universe. The existence of an intergalactic magnetic field （IGMF） would deflect paths of electron-positron pairs that scatter CMB photons, causing some observable effects, such as time delay, an ex- tended halo, and a spectral change. Here we reanalyze the diffusion of an electron jet deflected by IGMF and propose a unified semi-analytical model. By using publicly available data from the Fermi/LAT detector and contemporaneous TeV observations, we find that the cascade photon flux is not significantly affected by the IGMF strength for non-variable blazars when the IGMF is weaker than ,-~ 10-16 G. This result is clearly different from previous works that analyzed the extended halo and time de- lay separately for non-variable blazars and flaring blazars. By applying our model to two extreme blazars （1ES 0229＋200 and 1ES 1218＋304）, we obtain the IGMF lower limit of order ≥10-13 --10-14 G in the non-variable case, which is a stronger constraint on the IGMF strength than previous works （≥10-16 ,-- 10-18 G）, and ≥10-18 -- 10-19 G in the case of flaring blazars. Furthermore, we study the light curves and extended halo of the cascade photons by considering the effects of the IGME展开更多
We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+42...We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3) and 2344+514. The observations were carried out in September-October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420-014, S5 0716+714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827. We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344+514 during our two weeks' observing run of the TeV gamma-ray source.展开更多
基金support of the Department of Atomic Energy,Government of India,under project identification No.RT4002supported by Fermi vip Investigator grants NNX08AN56G,NNX08AN56G,NNX09AV10G,and NNX15AU81G。
文摘We present the results of the multi-epoch broadband spectral study of 1ES 2344+514 and study the evolution of physical parameters.We used nearly simultaneous data obtained from 2017 June 6 to 2022 August 6(MJD 57910–59797)in optical,UV,X-ray andγ-ray wavebands from various instruments including Swift-UVOT,Swift-XRT,Nuclear Spectroscopic Telescope Array(NuSTAR),AstroSat(SXT and LAXPC),Fermi-LAT,and TeV flux from MAGIC.During 2017 July,1ES 2344+514 appeared to be in the highest flaring state compared to other periods.We used the 0.5–7.0 keV and 3.0–20.0 keV data,respectively,from SXT and LAXPC of AstroSat and also 0.3–8.0 keV and 3.0–79.0 keV data,respectively,from Swift-XRT and NuSTAR.A joint fit between SXT and LAXPC,and between Swift-XRT and NuSTAR has been done for constraining the synchrotron peak.A clear shift in the synchrotron peak has been observed,which included 1ES 2344+514 in the HSP BL Lac family.A“harder-when-brighter”trend is observed in X-rays,and the opposite trend,i.e.,“softer-when-brighter,”is seen in theγ-rays.The multi-epoch broadband spectral energy distributions(SEDs)of this source were built and studied to get an idea of the radiation processes.The SEDs were fitted using a steady-state leptonic one-zone synchrotron+SSC model,and the fitted parameters of the emission region are consistent with those of other TeV BL Lacs.In this study,we found a weak correlation tendency between bolometric luminosity and magnetic field(B),as well as between bolometric luminosity and the break Lorentz factor(γ_(break)).
基金supported by National Natural Science Foundation of China(Grant No.U1931106)Shandong Provincial Natural Science Foundation of China(Grant No.ZR2019YQ03)Project of Shandong Qing Chuang Science and Technology Plan(Grant No.2019KJJ006)。
文摘We analyzed the optical monitoring data in the R band of Te V blazar 1ES 1959+650 from 2002 to 2018,and provided evidence of a quasi-periodic oscillation in this object.The light curve shows a stable and persistent periodicity at~540 days,detected by the Lomb–Scargle periodogram,Jurkevich and weighted wavelet z-transform techniques.The red noise power spectrum was estimated using the PSRESP method,and this period was found to be at>3σsignificance level.There are also two possible periodicities at~268 and~1100 days detected by all three methods.However,their significance levels are relatively low,and thus these two periods cannot be verified by the present data.We discuss several possible physical models that could explain the periodic variability in this object.
基金support from the National Key R & D Program of China (Grant No.2020YFE0202100)supported by the National Natural Science Foundation of China (Grant 11773036)+2 种基金by the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences (Grant Nos.XDA15052600 and XDA15016500)supported by the Natural Science Foundation of Guangxi (2018GXUSFGA281007 & 2020GXNSFDA238018)by the Bagui Young Scholars Program。
文摘We here report a monitor of the BL Lac object 1 ES 1218+304 in both B-and R-bands by the GWAC-F60 A telescope in eight nights,when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups.Both ANOVA and χ^(2)-test enable us to clearly reveal an intraday variability in optical wavelengths in seven out of the eight nights.A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights,which can be well explained by the shock-in-jet model.In addition,a quasi-periodic oscillation phenomenon in both bands could be tentatively identified in the first night.A positive delay between the two bands has been revealed in three out of the eight nights,and a negative one in the other nights.The identified minimum time delay enables us to estimate the MBH=2.8 × 10^(7) M_(⊙) that is invalid.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10778702 and 10803005)the 973 Program (2009CB824800)Yunnan Province under grant 2009 OC
文摘The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with the Suzaku, MAGICand VERITAS telescopes, clearly reveal nonthermal power-law spectra. We study thebroadband nonthermal spectra of the two sources by using a combination of a one-zone homogeneous synchrotron self-Compton （SSC） model and an inhomogeneousconical jet model, where the new external background light （EBL） model is taken intoaccount. The results show that （1） the nonthermal emissions of the two blazars, rang-ing from X-rays to VHE γ-rays, are from the homogeneous zone whereas the emis-sions in the radio bands can be explained as the radiation from the inhomogeneousconical jet; （2） a strict lower-limit EBL model can be used to explain their observedspectra well.
基金supported by the National Basic Research Program of China(973 Program)under grant 2014CB845800the National Natural Science Foundation of China under grant No.11033002
文摘Primary gamma rays emitted from extragalactic very-high-energy （VHE） sources, such as blazars, will generate cascade radiation in intergalactic space with a scale of -- 100 Mpc, for z - 0.1 and Eγ -1 TeV. These cascades proceed through electron-positron pair production and inverse Compton （IC） scattering in the cosmic background radiation fields, mainly cosmic microwave background （CMB） radiation and extragalactic background light in the voids of the universe. The existence of an intergalactic magnetic field （IGMF） would deflect paths of electron-positron pairs that scatter CMB photons, causing some observable effects, such as time delay, an ex- tended halo, and a spectral change. Here we reanalyze the diffusion of an electron jet deflected by IGMF and propose a unified semi-analytical model. By using publicly available data from the Fermi/LAT detector and contemporaneous TeV observations, we find that the cascade photon flux is not significantly affected by the IGMF strength for non-variable blazars when the IGMF is weaker than ,-~ 10-16 G. This result is clearly different from previous works that analyzed the extended halo and time de- lay separately for non-variable blazars and flaring blazars. By applying our model to two extreme blazars （1ES 0229＋200 and 1ES 1218＋304）, we obtain the IGMF lower limit of order ≥10-13 --10-14 G in the non-variable case, which is a stronger constraint on the IGMF strength than previous works （≥10-16 ,-- 10-18 G）, and ≥10-18 -- 10-19 G in the case of flaring blazars. Furthermore, we study the light curves and extended halo of the cascade photons by considering the effects of the IGME
基金Supported by the National Natural Science Foundation of China
文摘We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420-014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3) and 2344+514. The observations were carried out in September-October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420-014, S5 0716+714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827. We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344+514 during our two weeks' observing run of the TeV gamma-ray source.
