HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT
HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object, but that is also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported by some of the observed unusual characteristics. I...
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todo:paper_0004637X_v822_n2_p_Straal2023-10-03T14:02:40Z HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT Straal, S.M. Gabányi, K.É. Van Leeuwen, J. Clarke, T.E. Dubner, G. Frey, S. Giacani, E. Paragi, Z. BL Lacertae objects: individual (HESS J1943+213) pulsars: general HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object, but that is also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported by some of the observed unusual characteristics. In order to finally classify and understand this object, we took a three-pronged approach, through time-domain, high angular resolution, and multi-frequency radio studies. First, our deep time-domain observations with the Arecibo telescope failed to uncover the putative pulsar powering the proposed PWN. We conclude with ∼70% certainty that HESS J1943 +213 does not host a pulsar. Second, long-baseline interferometry of the source with e-MERLIN at 1.5 and 5 GHz shows only a core, that is, a point source at ∼1-100 mas resolution. Its 2013 flux density is about one-third lower than that detected in the 2011 observations with similar resolution. This radio variability of the core strengthens the HBL object hypothesis. Third, additional evidence against the PWN scenario comes from the radio spectrum we compiled. The extended structure follows a power-law behavior with spectral index α= -0.54 ± 0.04 while the core component displays a flat spectrum (α= -0.03 ± 0.03). In contrast, the radio synchrotron emission of PWNe predicts a single power-law distribution. Overall, we rule out the PWN hypothesis and conclude that the source is a BL Lac object. The consistently high fraction (70%) of the flux density from the extended structure then leads us to conclude that HESS J1943+213 must be a non-classical HBL object. © 2016. The American Astronomical Society. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0004637X_v822_n2_p_Straal |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
BL Lacertae objects: individual (HESS J1943+213) pulsars: general |
| spellingShingle |
BL Lacertae objects: individual (HESS J1943+213) pulsars: general Straal, S.M. Gabányi, K.É. Van Leeuwen, J. Clarke, T.E. Dubner, G. Frey, S. Giacani, E. Paragi, Z. HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| topic_facet |
BL Lacertae objects: individual (HESS J1943+213) pulsars: general |
| description |
HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object, but that is also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported by some of the observed unusual characteristics. In order to finally classify and understand this object, we took a three-pronged approach, through time-domain, high angular resolution, and multi-frequency radio studies. First, our deep time-domain observations with the Arecibo telescope failed to uncover the putative pulsar powering the proposed PWN. We conclude with ∼70% certainty that HESS J1943 +213 does not host a pulsar. Second, long-baseline interferometry of the source with e-MERLIN at 1.5 and 5 GHz shows only a core, that is, a point source at ∼1-100 mas resolution. Its 2013 flux density is about one-third lower than that detected in the 2011 observations with similar resolution. This radio variability of the core strengthens the HBL object hypothesis. Third, additional evidence against the PWN scenario comes from the radio spectrum we compiled. The extended structure follows a power-law behavior with spectral index α= -0.54 ± 0.04 while the core component displays a flat spectrum (α= -0.03 ± 0.03). In contrast, the radio synchrotron emission of PWNe predicts a single power-law distribution. Overall, we rule out the PWN hypothesis and conclude that the source is a BL Lac object. The consistently high fraction (70%) of the flux density from the extended structure then leads us to conclude that HESS J1943+213 must be a non-classical HBL object. © 2016. The American Astronomical Society. All rights reserved. |
| format |
JOUR |
| author |
Straal, S.M. Gabányi, K.É. Van Leeuwen, J. Clarke, T.E. Dubner, G. Frey, S. Giacani, E. Paragi, Z. |
| author_facet |
Straal, S.M. Gabányi, K.É. Van Leeuwen, J. Clarke, T.E. Dubner, G. Frey, S. Giacani, E. Paragi, Z. |
| author_sort |
Straal, S.M. |
| title |
HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| title_short |
HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| title_full |
HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| title_fullStr |
HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| title_full_unstemmed |
HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT |
| title_sort |
hess j1943+213: a non-classical high-frequency-peaked bl lac object |
| url |
http://hdl.handle.net/20.500.12110/paper_0004637X_v822_n2_p_Straal |
| work_keys_str_mv |
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1807316537272434688 |