The nature of transition blazars
Blazars are classically divided into the BL Lacertae (BLL) and flat-spectrum radio quasar (FSRQ) subclasses, corresponding to radiatively inefficient and efficient accretion regimes, respectively, largely based on the equivalent width (EW) of their optical broad emission lines (BELs). However, EW-ba...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing
2014
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| Online Access: | http://hdl.handle.net/20.500.11937/52594 |
| _version_ | 1848758965048967168 |
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| author | Ruan, J. Anderson, S. Plotkin, Richard Brandt, W. Burnett, T. Myers, A. Schneider, D. |
| author_facet | Ruan, J. Anderson, S. Plotkin, Richard Brandt, W. Burnett, T. Myers, A. Schneider, D. |
| author_sort | Ruan, J. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Blazars are classically divided into the BL Lacertae (BLL) and flat-spectrum radio quasar (FSRQ) subclasses, corresponding to radiatively inefficient and efficient accretion regimes, respectively, largely based on the equivalent width (EW) of their optical broad emission lines (BELs). However, EW-based classification criteria are not physically motivated, and a few blazars have previously "transitioned" from one subclass to the other. We present the first systematic search for these transition blazars in a sample of 602 unique pairs of repeat spectra of 354 blazars in the Sloan Digital Sky Survey, finding six clear cases. These transition blazars have bolometric Eddington ratios of ~0.3 and low-frequency synchrotron peaks, and are thus FSRQ-like. We show that the strong EW variability (up to an unprecedented factor of >60) is due to swamping of the BELs from variability in jet continuum emission, which is stronger in amplitude and shorter in timescale than typical blazars. Although these transition blazars appear to switch between FSRQ and BLL according to the phenomenologically based EW scheme, we show that they are most likely rare cases of FSRQs with radiatively efficient accretion flows and especially strongly beamed jets. These results have implications for the decrease of the apparent BLL population at high redshifts, and may lend credence to claims of a negative BLL redshift evolution. |
| first_indexed | 2025-11-14T09:52:22Z |
| format | Journal Article |
| id | curtin-20.500.11937-52594 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:52:22Z |
| publishDate | 2014 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-525942017-09-13T15:48:31Z The nature of transition blazars Ruan, J. Anderson, S. Plotkin, Richard Brandt, W. Burnett, T. Myers, A. Schneider, D. Blazars are classically divided into the BL Lacertae (BLL) and flat-spectrum radio quasar (FSRQ) subclasses, corresponding to radiatively inefficient and efficient accretion regimes, respectively, largely based on the equivalent width (EW) of their optical broad emission lines (BELs). However, EW-based classification criteria are not physically motivated, and a few blazars have previously "transitioned" from one subclass to the other. We present the first systematic search for these transition blazars in a sample of 602 unique pairs of repeat spectra of 354 blazars in the Sloan Digital Sky Survey, finding six clear cases. These transition blazars have bolometric Eddington ratios of ~0.3 and low-frequency synchrotron peaks, and are thus FSRQ-like. We show that the strong EW variability (up to an unprecedented factor of >60) is due to swamping of the BELs from variability in jet continuum emission, which is stronger in amplitude and shorter in timescale than typical blazars. Although these transition blazars appear to switch between FSRQ and BLL according to the phenomenologically based EW scheme, we show that they are most likely rare cases of FSRQs with radiatively efficient accretion flows and especially strongly beamed jets. These results have implications for the decrease of the apparent BLL population at high redshifts, and may lend credence to claims of a negative BLL redshift evolution. 2014 Journal Article http://hdl.handle.net/20.500.11937/52594 10.1088/0004-637X/797/1/19 Institute of Physics Publishing fulltext |
| spellingShingle | Ruan, J. Anderson, S. Plotkin, Richard Brandt, W. Burnett, T. Myers, A. Schneider, D. The nature of transition blazars |
| title | The nature of transition blazars |
| title_full | The nature of transition blazars |
| title_fullStr | The nature of transition blazars |
| title_full_unstemmed | The nature of transition blazars |
| title_short | The nature of transition blazars |
| title_sort | nature of transition blazars |
| url | http://hdl.handle.net/20.500.11937/52594 |