The Changing-look Blazar B2 1420+32
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- Oklahoma City Univ., OK (United States). Homer L. Dodge Department of Physics and Astronomy; OSTI
- Oklahoma City Univ., OK (United States). Homer L. Dodge Department of Physics and Astronomy
- Peking Univ., Beijing (China). Kavli Institute for Astronomy and Astrophysics, Department of Astronomy
- Guangxi University, People's Republic of China. School of Physical Science and Technology
- The Ohio State Univ., Columbus, OH (United States). Department of Astronomy
- DOE CSGF Fellow; University of Hawai'i at Manoa,, Honolulu, HI (United States). Institute for Astronomy
- NSF Graduate Research Fellow; The Ohio State Univ., Columbus, OH (United States). Department of Astronomy
- Liverpool John Moores University, Liverpool (United Kingdom). Astrophysics Research Institute
- The Ohio State Univ., Columbus, OH (United States). Department of Astronomy; The Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics
- University of Hawai'i at Manoa,, Honolulu, HI (United States). Institute for Astronomy
- Peking Univ., Beijing (China). Kavli Institute for Astronomy and Astrophysics
- The Observatories of the Carnegie Institution for Science, CA (United States)
- Peking Univ., Beijing (China). Kavli Institute for Astronomy and Astrophysic
- Universidad Diego Portales, Santiago, Chile. Núcleo de Astronomía de la Facultad de Ingeniería y Ciencias,
- Chinese Academy of Sciences, Shanghai. People's Republic of China. Shanghai Astronomical Observatory,
- Xiamen University, Xiamen, Fujian, People's Republic of China. Department of Astronomy,
Abstract Blazars are active galactic nuclei with their relativistic jets pointing toward the observer, comprising two major subclasses, flat-spectrum radio quasars (FSRQs) and BL Lac objects. We present multiwavelength photometric and spectroscopic monitoring observations of the blazar B2 1420+32, focusing on its outbursts in 2018–2020. Multiepoch spectra show that the blazar exhibited large-scale spectral variability in both its continuum and line emission, accompanied by dramatic gamma-ray and optical variability by factors of up to 40 and 15, respectively, on week to month timescales. Over the last decade, the gamma-ray and optical fluxes increased by factors of 1500 and 100, respectively. B2 1420+32 was an FSRQ with broad emission lines in 1995. Following a series of flares starting in 2018, it transitioned between BL Lac and FSRQ states multiple times, with the emergence of a strong Fe pseudocontinuum. Two spectra also contain components that can be modeled as single-temperature blackbodies of 12,000 and 5200 K. Such a collection of “changing-look” features has never been observed previously in a blazar. We measure gamma-ray–optical and interband optical lags implying emission-region separations of less than 800 and 130 gravitational radii, respectively. Since most emission-line flux variations, except the Fe continuum, are within a factor of 2–3, the transitions between FSRQ and BL Lac classifications are mainly caused by the continuum variability. The large Fe continuum flux increase suggests the occurrence of dust sublimation releasing more Fe ions in the central engine and an energy transfer from the relativistic jet to subrelativistic emission components.
- Research Organization:
- Krell Institute, Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0019323
- OSTI ID:
- 1853060
- Journal Information:
- The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 913; ISSN 0004-637X
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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