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dc.contributor.author
Marchesini, Ezequiel Joaquín
dc.contributor.author
Paggi, A.
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Massaro, F.
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Masetti, N.
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D'Abrusco, R.
dc.contributor.author
Andruchow, Ileana
dc.date.available
2021-11-01T16:53:02Z
dc.date.issued
2020-06
dc.identifier.citation
Marchesini, Ezequiel Joaquín; Paggi, A.; Massaro, F.; Masetti, N.; D'Abrusco, R.; et al.; The γ -ray sky seen at X-ray energies: II. The swift hunt of fermi BL lac objects among unidentified γ -ray sources; EDP Sciences; Astronomy and Astrophysics; 638; 6-2020; 1-13
dc.identifier.issn
0004-6361
dc.identifier.uri
http://hdl.handle.net/11336/145628
dc.description.abstract
Context. Nearly 50% of all sources detected by the Fermi Large Area Telescope are classified as blazars or blazar candidates, one of the most elusive classes of active galaxies. Additional blazars can also be hidden within the sample of unidentified or unassociated γ-ray sources (UGSs) that constitute about one-third of all gamma-ray sources detected to date. We recently confirmed that the large majority of Fermi blazars of the BL Lac subclass have an X-ray counterpart. Aims. Using the X-ray properties of a BL Lac training set and combining these with archival multifrequency information, we aim to search for UGSs that could have a BL Lac source within their γ-ray positional uncertainty regions. Methods. We reduced and analyzed the Swift X-ray observations of a selected sample of 327 UGSs. We then compared the X-ray fluxes and hardness ratios of all sources detected in the pointed fields with those of known Fermi BL Lacs. Results. We find at least one X-ray source, lying within the γ-ray positional uncertainty at 95% confidence level, for 223 UGSs and a total of 464 X-ray sources in all fields analyzed. The X-ray properties of a large fraction of them, eventually combined with radio, infrared, and optical information, exhibit BL Lac multi-frequency behavior, thus allowing us to select high-confidence BL Lac candidates; some of them were recently observed during our optical spectroscopic campaign which confirmed their nature. Conclusions. We find that out of 50 X-ray sources that were confirmed as BL Lacs through optical spectroscopy, 12 do not show canonical mid-infrared or radio BL Lac properties. This indicates that the selection of X-ray BL Lac candidates is a strong method to find new counterparts within Fermi UGSs. Finally, we pinpoint a sample of 32 Swift/XRT candidate counterparts to Fermi UGSs that are most likely BL Lac objects.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
EDP Sciences
dc.rights
info:eu-repo/semantics/restrictedAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
GALAXIES: ACTIVE
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GALAXIES: NUCLEI
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GALAXIES: JETS
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BL LACERTAE OBJECTS: GNERAL
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X-RAYS: GLAXIES
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GAMMA RAYS: GALAXIES
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Astronomía
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Ciencias Físicas
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CIENCIAS NATURALES Y EXACTAS
dc.title
The γ -ray sky seen at X-ray energies: II. The swift hunt of fermi BL lac objects among unidentified γ -ray sources
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2021-09-06T17:46:48Z
dc.identifier.eissn
1432-0746
dc.journal.volume
638
dc.journal.pagination
1-13
dc.journal.pais
Francia
dc.journal.ciudad
Paris
dc.description.fil
Fil: Marchesini, Ezequiel Joaquín. Universita Di Torino. Dipartimento Di Física Generale; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Istituto Nazionale Di Fisica Nucleare; Italia. Istituto Nazionale di Astrofisica; Italia
dc.description.fil
Fil: Paggi, A.. Universita Di Torino. Dipartimento Di Física Generale; Italia
dc.description.fil
Fil: Massaro, F.. Universita Di Torino. Dipartimento Di Física Generale; Italia
dc.description.fil
Fil: Masetti, N.. Universidad Andrés Bello; Chile. Istituto Nazionale di Astrofisica; Italia
dc.description.fil
Fil: D'Abrusco, R.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
dc.description.fil
Fil: Andruchow, Ileana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina
dc.journal.title
Astronomy and Astrophysics
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/https://www.aanda.org/10.1051/0004-6361/201936928
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1051/0004-6361/201936928
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