H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017
Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E ≥ 100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, wh...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/172347 |
| Acceso en línea: | https://hdl.handle.net/2445/172347 |
| Access Level: | acceso abierto |
| Palabra clave: | Raigs gamma Física de partícules Quàsars Gamma rays Particle physics Quasars |
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H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017H. E. S. S. CollaborationCerruti, MatteoRaigs gammaFísica de partículesQuàsarsGamma raysParticle physicsQuasarsContext. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E ≥ 100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV-GeV γ-ray flaring activity from the FSRQ PKS 0736+017 (z = 0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the γ-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a γ-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The γ-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The γ-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the γ-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region rBLR with a bulk Lorentz factor Γ ≃ 20, or at the level of the radius of the dusty torus rtorus with Γ ≃ 60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z = 0.189 is the nearest so far. The location of the γ-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments.EDP Sciences2020202020202020info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersion11 p.application/pdfhttps://hdl.handle.net/2445/172347Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB))reponame:Recercat. Dipósit de la Recerca de Catalunyainstname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)InglésReproducció del document publicat a: https://doi.org/10.1051/0004-6361/201935906Astronomy & Astrophysics, 2020, vol. 633, p. A162https://doi.org/10.1051/0004-6361/201935906(c) The European Southern Observatory (ESO), 2020info:eu-repo/semantics/openAccessoai:recercat.cat:2445/1723472026-05-29T05:05:01Z |
| dc.title.none.fl_str_mv |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| title |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| spellingShingle |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 H. E. S. S. Collaboration Raigs gamma Física de partícules Quàsars Gamma rays Particle physics Quasars |
| title_short |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| title_full |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| title_fullStr |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| title_full_unstemmed |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| title_sort |
H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017 |
| dc.creator.none.fl_str_mv |
H. E. S. S. Collaboration Cerruti, Matteo |
| author |
H. E. S. S. Collaboration |
| author_facet |
H. E. S. S. Collaboration Cerruti, Matteo |
| author_role |
author |
| author2 |
Cerruti, Matteo |
| author2_role |
author |
| dc.subject.none.fl_str_mv |
Raigs gamma Física de partícules Quàsars Gamma rays Particle physics Quasars |
| topic |
Raigs gamma Física de partícules Quàsars Gamma rays Particle physics Quasars |
| description |
Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E ≥ 100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV-GeV γ-ray flaring activity from the FSRQ PKS 0736+017 (z = 0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the γ-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a γ-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The γ-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The γ-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the γ-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region rBLR with a bulk Lorentz factor Γ ≃ 20, or at the level of the radius of the dusty torus rtorus with Γ ≃ 60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z = 0.189 is the nearest so far. The location of the γ-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments. |
| publishDate |
2020 |
| dc.date.none.fl_str_mv |
2020 2020 2020 2020 |
| dc.type.none.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion |
| format |
article |
| status_str |
publishedVersion |
| dc.identifier.none.fl_str_mv |
https://hdl.handle.net/2445/172347 |
| url |
https://hdl.handle.net/2445/172347 |
| dc.language.none.fl_str_mv |
Inglés |
| language_invalid_str_mv |
Inglés |
| dc.relation.none.fl_str_mv |
Reproducció del document publicat a: https://doi.org/10.1051/0004-6361/201935906 Astronomy & Astrophysics, 2020, vol. 633, p. A162 https://doi.org/10.1051/0004-6361/201935906 |
| dc.rights.none.fl_str_mv |
(c) The European Southern Observatory (ESO), 2020 info:eu-repo/semantics/openAccess |
| rights_invalid_str_mv |
(c) The European Southern Observatory (ESO), 2020 |
| eu_rights_str_mv |
openAccess |
| dc.format.none.fl_str_mv |
11 p. application/pdf |
| dc.publisher.none.fl_str_mv |
EDP Sciences |
| publisher.none.fl_str_mv |
EDP Sciences |
| dc.source.none.fl_str_mv |
Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB)) reponame:Recercat. Dipósit de la Recerca de Catalunya instname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
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Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
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Recercat. Dipósit de la Recerca de Catalunya |
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Recercat. Dipósit de la Recerca de Catalunya |
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15,811543 |