袁聿海, 陳新兵

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3C345的射電偏振變化

袁聿海, 陳新兵

(廣州大學(xué) 實(shí)驗(yàn)中心, 廣東, 廣州, 510005)

基于密歇根大學(xué)射電天文臺(tái)數(shù)據(jù)庫(kù)(University of Michigan Radio Observatory Datebase—UMRAO), 分析了3C345在射電波段的偏振性質(zhì). 利用功率譜方法得到其在4.8、8和14.5 GHz處的長(zhǎng)期偏振變化的周期分別為: 11.1±1.7、11.8±1.5和10.9±1.6 yr.

blazer; 3C345; 偏振變化

3C345是一個(gè)blazar, 紅移= 0.595[1]. 該源的射電結(jié)構(gòu)以平譜的射電核為主導(dǎo), 具有單邊的噴流[2]. 該源包含延展的射電結(jié)構(gòu), 具有從sub-pc到kpc的尺度[3].

一些作者分析了3C345的長(zhǎng)期光變性質(zhì). Webb等(1988)發(fā)現(xiàn)光學(xué)波段的光變周期是5.6 yr和11.4 yr[12]. Zhang, Xie和Bai(1998)得到光學(xué)波段的光變周期是10.1±0.8 yr[13]. Dong 等(2010)利用光學(xué)波段的光變曲線得到其變化周期是4.54 yr和9.59 yr[14]. Wang和Yang(2010)發(fā)現(xiàn)在22 GHz波段的光變周期是8.8 yr[15]. Fan 等(2007)利用相同數(shù)據(jù)庫(kù)的光變數(shù)據(jù), 得到在8 GHz的光變周期是11.3±0.4 yr, 在14.5 GHz的光變周期是10.9±0.7 yr[16].

但有關(guān)3C345長(zhǎng)期偏振變化的研究還沒(méi)有, 而這正是本文的研究重點(diǎn).

1 偏振數(shù)據(jù)

偏振數(shù)據(jù)來(lái)自UMRAO數(shù)據(jù)庫(kù)(University of Michigan Radiio Astronomy Observatory Database). 該數(shù)據(jù)庫(kù)提供了許多blazars的偏振測(cè)光數(shù)據(jù). 3C345的偏振數(shù)據(jù)顯示: 在4.8 GHz, 存在691個(gè)觀測(cè)數(shù)據(jù), 其范圍從(0.53±0.16)%到(6.56±0.17)%, 平均值是(3.53±1.23)%; 在8 GHz, 存在919個(gè)觀測(cè)數(shù)據(jù), 其范圍從(0.27± 0.14)%到(6.21±0.36)%, 平均值是(2.69±1.06)%; 在14.5 GHz處, 存在694個(gè)觀測(cè)數(shù)據(jù), 其范圍從(0.14± 0.12)%到(5.41±0.69)%, 平均值(2.51±1.19)%.

圖1 3C345在4.8 GHz的偏振變化

圖2 3C345在8 GHz的偏振變

圖3 3C345在14.5 GHz的偏振變化

圖4 利用PS得到在4.8GHz的偏振周期

2 方法和結(jié)果

利用功率譜方法(PS)來(lái)計(jì)算3C345在3個(gè)波段的射電偏振變化[17], 再利用HMHW(半高半寬)得到相應(yīng)誤差.

圖5 利用PS得到在8 GHz的偏振周期

圖6 利用PS得到在14.5 GHz的偏振周期

3 討論和結(jié)論

Wallinder(1992)[18]提出利用blazar的時(shí)標(biāo)性質(zhì)來(lái)分析薄吸積盤的熱不穩(wěn)定性, 其表述可簡(jiǎn)單概括如下:

本文, 我們利用功率譜方法來(lái)分析了Blazar 3C345長(zhǎng)期偏振變化的周期性質(zhì), 結(jié)果顯示其變化周期是: 在4.8 GHz,4.8 GHz=11.1±1.7 yr; 在8 GHz,8 GHz=11.8±1.5 yr; 在14.5 GHz,14.5 GHz=10.9±1.6 yr.

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[12] Webb J R, Smith A G, Leacock R J, et al. Optical observations of 22 violently variable extragalactic sources-1968-1986[J]. AJ, 1988, 95: 374-397.

[13] Zhang X, Xie G Z, Bai J M. A historical light curve of 3C 345 and its periodic analysis[J]. A&A, 1998, 330: 469-473.

[14] Dong F T, Zhang H J, Mao L S, et al. WWZ Analysis on the Variability Data of Quasar 3C 345[J]. ChA&A, 2010, 34: 357-366.

[15] Wang H T, Yang J Y. An Analysis of the Light Variations of 3C 345 and 3C 273[J]. ChA&A, 2010, 34: 343-349.

[16] Fan J H, Liu Y, Yuan Y H, et al. Radio variability properties for radio sources[J]. A&A, 2007, 462 : 547-552.

[17] Press W H., Teukolsky S A, Vetterling W T, et al. Cambridge University Press : Numerical Recipes in Fortran[M]. 1992 : 565.

[18] Wallinder F H, Kato S, Abramowicz M A. Variability of the central region in active galactic nuclei[J]. A&ARv, 1992, 4: 79-122.

[19] Lobanov A P, Roland J. A supermassive binary black hole in the quasar 3C 345[J]. A&A, 2005, 431: 831-846.

The radio polarized variability of 3C345

YUAN Yu-hai, CHEN Xin-bing

(Center for Experiment of Guangzhou University, Guangdong, Guangzhou, 510006)

Based on the database of University of Michigan Radio Observatory (UMRAO), We analyze the long-term polarized variability of 3C345. Using the method of the power spectrum, we obtain the periodicities of the polarized variability at three bands, which are P4.8GHz=11.1±1.7 year, P8GHz=11.8±1.5 year, P14.5GHz=10.9±1.6 year.

blazer; 3C345; polarized variability

10.3969/j.issn.1672-6146.2012.03.005

P 142

1672-6146(2012)03-0015-03

2012-09-01

國(guó)家自然科學(xué)基金(10633010)

袁聿海(1980-), 男, 實(shí)驗(yàn)師, 博士,研究方向: 天體物理. E-mail: yh_yuan@gzhu.edu.cn

(責(zé)任編校 :劉曉霞)