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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Detalles Bibliográficos
Publicado: 2016
Materias:
BL Lacertae objects: individual (HESS J1943+213)
pulsars: general
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v822_n2_p_Straal
http://hdl.handle.net/20.500.12110/paper_0004637X_v822_n2_p_Straal
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_0004637X_v822_n2_p_Straal
record_format dspace
spelling paper:paper_0004637X_v822_n2_p_Straal2023-06-08T14:29:17Z HESS J1943+213: A NON-CLASSICAL HIGH-FREQUENCY-PEAKED BL LAC OBJECT 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. 2016 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v822_n2_p_Straal 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
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.
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
publishDate 2016
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v822_n2_p_Straal
http://hdl.handle.net/20.500.12110/paper_0004637X_v822_n2_p_Straal
_version_ 1768542916455694336

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