B2 1308+326: A Changing-look Blazar or Not?
In our previous study, we identified a shift in the synchrotron peak frequency of the blazar B2 1308+326 from 10 ^12.9 to 10 ^14.8 Hz during a flare, suggesting it could be a changing-look blazar (CLB). In this work, we investigate the changing-look behaviour of B2 1308+326 by analysing a newly acqu...
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IOP Publishing
2024-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9b7c |
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| author | Ashwani Pandey Chen Hu Jian-Min Wang Bożena Czerny Yong-Jie Chen Yu-Yang Songsheng Yi-Lin Wang Hao Zhang Jesús Aceituno |
| author_facet | Ashwani Pandey Chen Hu Jian-Min Wang Bożena Czerny Yong-Jie Chen Yu-Yang Songsheng Yi-Lin Wang Hao Zhang Jesús Aceituno |
| author_sort | Ashwani Pandey |
| collection | DOAJ |
| description | In our previous study, we identified a shift in the synchrotron peak frequency of the blazar B2 1308+326 from 10 ^12.9 to 10 ^14.8 Hz during a flare, suggesting it could be a changing-look blazar (CLB). In this work, we investigate the changing-look behaviour of B2 1308+326 by analysing a newly acquired optical spectrum and comparing it with an archival spectrum. We find that between the two epochs, the continuum flux increased by a factor of ~4.4, while the Mg ii emission line flux decreased by a factor of 1.4 ± 0.2. Additionally, the equivalent width of the Mg ii line reduced from ~20 to ~3 Å, indicating an apparent shift from a flat-spectrum radio quasar (FSRQ) class to a BL Lacertae (BL Lac) class. Despite this apparent change, the ratio of accretion disk luminosity to Eddington luminosity remains >10 ^−2 during both epochs, indicating efficient accretion persists in B2 1308+326. The measured black hole mass remains consistent with an average $\mathrm{log}{M}_{{\rm{BH}}}=8.44$ M _⊙ . Our findings suggest that B2 1308+326 is not a genuine CLB but rather an intrinsic FSRQ that emerges as a BL Lac during high-flux states due to enhanced nonthermal emission. |
| format | Article |
| id | doaj-art-c872789c771f4ec3b4a3552cd14160ab |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-c872789c771f4ec3b4a3552cd14160ab2025-08-20T02:52:58ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01978212010.3847/1538-4357/ad9b7cB2 1308+326: A Changing-look Blazar or Not?Ashwani Pandey0https://orcid.org/0000-0003-3820-0887Chen Hu1Jian-Min Wang2https://orcid.org/0000-0001-9449-9268Bożena Czerny3https://orcid.org/0000-0001-5848-4333Yong-Jie Chen4https://orcid.org/0000-0003-4280-7673Yu-Yang Songsheng5https://orcid.org/0000-0003-4042-7191Yi-Lin Wang6Hao Zhang7https://orcid.org/0000-0002-5595-0447Jesús Aceituno8https://orcid.org/0000-0003-0487-1105Key Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.com; Department of Physics and Astronomy, University of Utah , Salt Lake City, UT 84112, USA; Center for Theoretical Physics , Polish Academy of Sciences, Al.Lotnikov 32/46, PL-02-668 Warsaw, PolandKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.comKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.com; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China; National Astronomical Observatories of China, The Chinese Academy of Sciences , 20A Datun Road, Beijing 100020, People’s Republic of ChinaCenter for Theoretical Physics , Polish Academy of Sciences, Al.Lotnikov 32/46, PL-02-668 Warsaw, PolandKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.com; Dongguan Neutron Science Center , 1 Zhongziyuan Road, Dongguan 523808, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.comKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.com; School of Physical Science, University of Chinese Academy of Sciences , 19A Yuquan Road, Beijing 100049, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ashwanitapan@gmail.com; School of Physical Science, University of Chinese Academy of Sciences , 19A Yuquan Road, Beijing 100049, People’s Republic of ChinaCentro Astronomico Hispano Alemán , Sierra de los filabres sn, E-04550 Gergal, Almería, Spain; Instituto de Astrofísica de Andalucía (CSIC) , Glorieta de la astronomía sn, E-18008 Granada, SpainIn our previous study, we identified a shift in the synchrotron peak frequency of the blazar B2 1308+326 from 10 ^12.9 to 10 ^14.8 Hz during a flare, suggesting it could be a changing-look blazar (CLB). In this work, we investigate the changing-look behaviour of B2 1308+326 by analysing a newly acquired optical spectrum and comparing it with an archival spectrum. We find that between the two epochs, the continuum flux increased by a factor of ~4.4, while the Mg ii emission line flux decreased by a factor of 1.4 ± 0.2. Additionally, the equivalent width of the Mg ii line reduced from ~20 to ~3 Å, indicating an apparent shift from a flat-spectrum radio quasar (FSRQ) class to a BL Lacertae (BL Lac) class. Despite this apparent change, the ratio of accretion disk luminosity to Eddington luminosity remains >10 ^−2 during both epochs, indicating efficient accretion persists in B2 1308+326. The measured black hole mass remains consistent with an average $\mathrm{log}{M}_{{\rm{BH}}}=8.44$ M _⊙ . Our findings suggest that B2 1308+326 is not a genuine CLB but rather an intrinsic FSRQ that emerges as a BL Lac during high-flux states due to enhanced nonthermal emission.https://doi.org/10.3847/1538-4357/ad9b7cFlat-spectrum radio quasarsBlazarsActive galactic nucleiRadio loud quasarsRelativistic jets |
| spellingShingle | Ashwani Pandey Chen Hu Jian-Min Wang Bożena Czerny Yong-Jie Chen Yu-Yang Songsheng Yi-Lin Wang Hao Zhang Jesús Aceituno B2 1308+326: A Changing-look Blazar or Not? The Astrophysical Journal Flat-spectrum radio quasars Blazars Active galactic nuclei Radio loud quasars Relativistic jets |
| title | B2 1308+326: A Changing-look Blazar or Not? |
| title_full | B2 1308+326: A Changing-look Blazar or Not? |
| title_fullStr | B2 1308+326: A Changing-look Blazar or Not? |
| title_full_unstemmed | B2 1308+326: A Changing-look Blazar or Not? |
| title_short | B2 1308+326: A Changing-look Blazar or Not? |
| title_sort | b2 1308 326 a changing look blazar or not |
| topic | Flat-spectrum radio quasars Blazars Active galactic nuclei Radio loud quasars Relativistic jets |
| url | https://doi.org/10.3847/1538-4357/ad9b7c |
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