耀变体PKS 0537–441的光学谱特性
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摘要
利用耶鲁大学SMARTS数据库提供观测数据,得到了耀变体PKS 0537–441从2011年1月到2015年5月的光学B和R波段光变曲线,并计算了两波段对应的谱指数.使用离散相关函数法等方法对流量、谱指数及二者的相关性进行研究,结果表明:(1)PKS 0537-441光变剧烈,在长时标,中等时标爆发上升期和衰退期均表现出BWB(Bluer-When-Brighter)的光学谱特性,该特性可由喷流内的激波模型作出解释;(2)B和R波段流量变化有强相关性,且B波段流量变化领先R波段(35.62±8.63)d;(3)R波段可能具有(53.06±6.62)d和(273.88±20.69)d的准周期性光变.
We present the long-term light curves of the blazar PKS 0537–441 in the optical B and R bands during the period from January 2011 to May 2015 on the basis of the photometric data provided by the SMARTS Consortium, and calculate the corresponding colour indices. The linear regression and discrete correlation function methods have been performed on the light curves and the colour indices curve. The results can be summarized as follows:(1) the light curves in the B and R bands show large variabilities on various timescales, while the colour indices curve reveals significant fluctuations which indicates the variation of spectra. A general BWB(bluer-when-brighter) trend is confirmed in long-term timescales and in the ascent and descent states during flares;(2) the linear regression shows that the light curves in the B and R bands are well correlated. The results obtained by the discrete correlation function method which reveals that the flux variation in the B band led that in the R band by(35.62 ± 8.63) d;(3) the analysis of periodicity suggests that(53.06 ± 6.62) d and(273.88 ± 20.69) d are the possible periods in the R-band light curve.
We present the long-term light curves of the blazar PKS 0537–441 in the optical B and R bands during the period from January 2011 to May 2015 on the basis of the photometric data provided by the SMARTS Consortium, and calculate the corresponding colour indices. The linear regression and discrete correlation function methods have been performed on the light curves and the colour indices curve. The results can be summarized as follows:(1) the light curves in the B and R bands show large variabilities on various timescales, while the colour indices curve reveals significant fluctuations which indicates the variation of spectra. A general BWB(bluer-when-brighter) trend is confirmed in long-term timescales and in the ascent and descent states during flares;(2) the linear regression shows that the light curves in the B and R bands are well correlated. The results obtained by the discrete correlation function method which reveals that the flux variation in the B band led that in the R band by(35.62 ± 8.63) d;(3) the analysis of periodicity suggests that(53.06 ± 6.62) d and(273.88 ± 20.69) d are the possible periods in the R-band light curve.
引文
1 Urry C M,Padovani P.Unified schemes for radio-loud active galactic nuclei.Publ Astron Soc Pac,1995,107:803-845
2 Ulrich M H,Maraschi L,Urry C M.Variability of active galactic nuclei.Annu Rev Astron Astrophys,1997,35:445-502
3 B ttcher M,Reimer A,Sweeney K,et al.Leptonic and hadronic modeling of fermi-detected blazars.Astrophys J,2013,768:54-68
4 Liller W.The photometric history of the object identified with PKS 0537-441.Astrophys J Lett,1974,189:L101-L102
5 Romero G E,Cellone S A,Combi J A,et al.I.Optical microvariability of EGRET blazars.Astron Astrophys,2002,390:431-438
6 Impey C D,Tapia S.New blazars discovered by polarimetry.Astrophys J,1988,333:662-672
7 Lewis G F,Ibata R A.An investigation of gravitational lensing in the southern BL Lac PKS 0537-441.Astrophys J,2000,528:650-654
8 Heidt J,Jger K,Nilsson K,et al.PKS 0537-441:Extended[O II]emission and a binary QSO?Astron Astrophys,2003,406:565-577
9 Thompson D J,Bertsch D L,Fichtel C E,et al.Gamma radiation from blazar PKS 0537-441.Astrophys J,1993,410:87-89
10 Pucella G,D’Ammando F,Romano P,et al.AGILE detection of intenseγ-ray activity from the blazar PKS 0537-441 in October 2008.Astron Astrophys,2010,522:109-114
11 D’Ammando F,Antolini E,Tosti G,et al.Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations.Mon Not R Astron Soc,2013,431:2481-2492
12 Dolcini A,Covino S,Treves A,et al.Multiband photometry of the blazar PKS 0537-441:A major active state in December 2004-March 2005.Astron Astrophys,2005,443:L33-L36
13 Pian E,Romano P,Treves A,et al.Simultaneous swift and REM monitoring of the blazar PKS 0537-441 in 2005.Astrophys J,2007,664:106-116
14 Impiombato D,Covino S,Treves A,et al.Optical and infrared photometry of the blazar PKS 0537-441:Long and short timescale variability.Astrophys J Suppl Ser,2011,192:12-17
15 Sandrinelli A,Covino S,Treves A.Long and short term variability of seven blazars in six near-infrared/optical bands.Astron Astrophys,2014,562:79-98
16 Zhang B K,Wang S,Zhao X Y,et al.Long-term optical and infrared variability of the BL Lac object PKS 0537-441.Mon Not R Astron Soc,2013,428:3630-3635
17 Li X P,Zhang L,Luo Y H,et al.Colour variation of the BL Lacertae object PKS 0537-441.Mon Not R Astron Soc,2015,449:2750-2758
18 Sandrinelli A,Covino S,Treves A.Gamma-ray and optical oscillations in PKS 0537-441.Astrophys J,2016,820:20-26
19 Sandrinelli A,Covino S,Dotti M,et al.Quasi-periodicities at year-like timescales in blazars.Astron J,2016,151:54-68
20 Bonning E,Urry C M,Bailyn C,et al.Smarts optical and infrared monitoring of 12 gamma-ray bright blazars.Astrophys J,2012,756:13-29
21 M ecke A,Pohl M,Reich P,et al.On the correlation between radio and gamma ray luminosities of active galactic nuclei.Astron Astrophys,1997,320:33-40
22 Chatterjee R,Bailyn C D,Bonning E W,et al.Similarity of the optical-infrared andγ-ray time variability of Fermi blazars.Astrophys J,2012,749:191-205
23 Edelson R A,Krolik J H.The discrete correlation function-A new method for analyzing unevenly sampled variability data.Astrophys J,1988,333:646-659
24 Hufnagel B R,Bregman J N.Optical and radio variability in blazars.Astrophys J,1992,386:473-484
25 Peterson B M,Wanders I,Horne K,et al.On uncertainties in cross-correlation lags and the reality of wavelength-dependent continuum lags in active galactic nuclei,Publ Astron Soc Pac,1988,110:660-670
26 Zhang B K,Dai B Z,Zhang L,et al.The long-term optical behavior of BL Lac object S5 0716+714.Sci China-Phys Mech Astron,2010,53:1370-1374
27 Rani B,Gupta A C,Strigachev A,et al.Short-term flux and colour variations in low-energy peaked blazars.Mon Not R Astron Soc,2010,404:1992-2017
28 Lei M C,Wang J C.Te V blazar(in Chinese).Sci Sin-Phys Mech Astron,2015,45:119506[雷买昌,王建成.Te V耀变体.中国科学:物理学力学天文学,2015,45:119506]
29 Sillanpaa A,Haarala S,Valtonen M J,et al.OJ 287-Binary pair of supermassive black holes.Astrophys J,1988,325:628-634
30 Li X P,Zhang X,Zhang H J,et al.The characteristic periodicity analysis of the radio flux variability of BL Lac object Mkn 421(in Chinese).Sci Sin-Phys Mech Astron,2011,41:325-330[李孝攀,张雄,张皓晶,等.BL Lac天体Mkn 421射电流量变化周期特性.中国科学:物理学力学天文学,2011,41:325-330]
31 Zhang H J,Zhao G,Zhang X,et al.The characteristic periodicity analysis of the radio flux variability of quasar PKS 1510-089.Sci China Ser G-Phys Mech Astron,2009,52:1442-1448
32 Li X P,Zhang H J,Zhang X.Characteristic periodicity analysis of the X-ray flux variability of quasar PKS 1510-089(in Chinese).Acta Phys Sin,2011,60:089801[李孝攀,张皓晶,张雄.类星体PKS 1510-089的X射线流量变化周期特性.物理学报,2011,60:089801]
33 Wang H T,Su Y P.The analysis of radio and optical variability in blazar OQ 530(in Chinese).Sci Sin-Phys Mech Astron,2015,45:029801[王洪涛,苏彦苹.OQ 530射电和光学波段的光变分析.中国科学:物理学力学天文学,2015,45:029801]
(1)详见http://www.rem.inaf.it/
(2)详见http://www.astro.yale.edu/smarts/
2 Ulrich M H,Maraschi L,Urry C M.Variability of active galactic nuclei.Annu Rev Astron Astrophys,1997,35:445-502
3 B ttcher M,Reimer A,Sweeney K,et al.Leptonic and hadronic modeling of fermi-detected blazars.Astrophys J,2013,768:54-68
4 Liller W.The photometric history of the object identified with PKS 0537-441.Astrophys J Lett,1974,189:L101-L102
5 Romero G E,Cellone S A,Combi J A,et al.I.Optical microvariability of EGRET blazars.Astron Astrophys,2002,390:431-438
6 Impey C D,Tapia S.New blazars discovered by polarimetry.Astrophys J,1988,333:662-672
7 Lewis G F,Ibata R A.An investigation of gravitational lensing in the southern BL Lac PKS 0537-441.Astrophys J,2000,528:650-654
8 Heidt J,Jger K,Nilsson K,et al.PKS 0537-441:Extended[O II]emission and a binary QSO?Astron Astrophys,2003,406:565-577
9 Thompson D J,Bertsch D L,Fichtel C E,et al.Gamma radiation from blazar PKS 0537-441.Astrophys J,1993,410:87-89
10 Pucella G,D’Ammando F,Romano P,et al.AGILE detection of intenseγ-ray activity from the blazar PKS 0537-441 in October 2008.Astron Astrophys,2010,522:109-114
11 D’Ammando F,Antolini E,Tosti G,et al.Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations.Mon Not R Astron Soc,2013,431:2481-2492
12 Dolcini A,Covino S,Treves A,et al.Multiband photometry of the blazar PKS 0537-441:A major active state in December 2004-March 2005.Astron Astrophys,2005,443:L33-L36
13 Pian E,Romano P,Treves A,et al.Simultaneous swift and REM monitoring of the blazar PKS 0537-441 in 2005.Astrophys J,2007,664:106-116
14 Impiombato D,Covino S,Treves A,et al.Optical and infrared photometry of the blazar PKS 0537-441:Long and short timescale variability.Astrophys J Suppl Ser,2011,192:12-17
15 Sandrinelli A,Covino S,Treves A.Long and short term variability of seven blazars in six near-infrared/optical bands.Astron Astrophys,2014,562:79-98
16 Zhang B K,Wang S,Zhao X Y,et al.Long-term optical and infrared variability of the BL Lac object PKS 0537-441.Mon Not R Astron Soc,2013,428:3630-3635
17 Li X P,Zhang L,Luo Y H,et al.Colour variation of the BL Lacertae object PKS 0537-441.Mon Not R Astron Soc,2015,449:2750-2758
18 Sandrinelli A,Covino S,Treves A.Gamma-ray and optical oscillations in PKS 0537-441.Astrophys J,2016,820:20-26
19 Sandrinelli A,Covino S,Dotti M,et al.Quasi-periodicities at year-like timescales in blazars.Astron J,2016,151:54-68
20 Bonning E,Urry C M,Bailyn C,et al.Smarts optical and infrared monitoring of 12 gamma-ray bright blazars.Astrophys J,2012,756:13-29
21 M ecke A,Pohl M,Reich P,et al.On the correlation between radio and gamma ray luminosities of active galactic nuclei.Astron Astrophys,1997,320:33-40
22 Chatterjee R,Bailyn C D,Bonning E W,et al.Similarity of the optical-infrared andγ-ray time variability of Fermi blazars.Astrophys J,2012,749:191-205
23 Edelson R A,Krolik J H.The discrete correlation function-A new method for analyzing unevenly sampled variability data.Astrophys J,1988,333:646-659
24 Hufnagel B R,Bregman J N.Optical and radio variability in blazars.Astrophys J,1992,386:473-484
25 Peterson B M,Wanders I,Horne K,et al.On uncertainties in cross-correlation lags and the reality of wavelength-dependent continuum lags in active galactic nuclei,Publ Astron Soc Pac,1988,110:660-670
26 Zhang B K,Dai B Z,Zhang L,et al.The long-term optical behavior of BL Lac object S5 0716+714.Sci China-Phys Mech Astron,2010,53:1370-1374
27 Rani B,Gupta A C,Strigachev A,et al.Short-term flux and colour variations in low-energy peaked blazars.Mon Not R Astron Soc,2010,404:1992-2017
28 Lei M C,Wang J C.Te V blazar(in Chinese).Sci Sin-Phys Mech Astron,2015,45:119506[雷买昌,王建成.Te V耀变体.中国科学:物理学力学天文学,2015,45:119506]
29 Sillanpaa A,Haarala S,Valtonen M J,et al.OJ 287-Binary pair of supermassive black holes.Astrophys J,1988,325:628-634
30 Li X P,Zhang X,Zhang H J,et al.The characteristic periodicity analysis of the radio flux variability of BL Lac object Mkn 421(in Chinese).Sci Sin-Phys Mech Astron,2011,41:325-330[李孝攀,张雄,张皓晶,等.BL Lac天体Mkn 421射电流量变化周期特性.中国科学:物理学力学天文学,2011,41:325-330]
31 Zhang H J,Zhao G,Zhang X,et al.The characteristic periodicity analysis of the radio flux variability of quasar PKS 1510-089.Sci China Ser G-Phys Mech Astron,2009,52:1442-1448
32 Li X P,Zhang H J,Zhang X.Characteristic periodicity analysis of the X-ray flux variability of quasar PKS 1510-089(in Chinese).Acta Phys Sin,2011,60:089801[李孝攀,张皓晶,张雄.类星体PKS 1510-089的X射线流量变化周期特性.物理学报,2011,60:089801]
33 Wang H T,Su Y P.The analysis of radio and optical variability in blazar OQ 530(in Chinese).Sci Sin-Phys Mech Astron,2015,45:029801[王洪涛,苏彦苹.OQ 530射电和光学波段的光变分析.中国科学:物理学力学天文学,2015,45:029801]
(1)详见http://www.rem.inaf.it/
(2)详见http://www.astro.yale.edu/smarts/