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Jackson, Miranda
Publikasjoner (2 av 2) Visa alla publikasjoner
Chauvin, M., Florén, H.-G. -., Jackson, M., Kamae, T., Kataoka, J., Kiss, M., . . . Pearce, M. (2019). PoGO + polarimetric constraint on the synchrotron jet emission of Cygnus X-1. Monthly Notices of the Royal Astronomical Society: Letters, 483(1), L138-L143
Åpne denne publikasjonen i ny fane eller vindu >>PoGO + polarimetric constraint on the synchrotron jet emission of Cygnus X-1
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2019 (engelsk)Inngår i: Monthly Notices of the Royal Astronomical Society: Letters, ISSN 1745-3925, Vol. 483, nr 1, s. L138-L143Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We report a polarimetric constraint on the hard X-ray synchrotron jet emission from the Cygnus X-1 black hole binary system. The observational data were obtained using the PoGO+ hard X-ray polarimeter in 2016 July, when Cygnus X-1 was in the hard state. We have previously reported that emission from an extended corona with a low polarization fraction is dominating, and that the polarization angle is perpendicular to the disc surface. In the soft gamma-ray regime, a highly polarized synchrotron jet is reported with INTEGRAL observations. To constrain the polarization fraction and flux of such a jet component in the hard X-ray regime, we now extend analyses through vector calculations in the Stokes QU plane, where the dominant corona emission and the jet component are considered simultaneously. The presence of another emission component with different polarization angle could partly cancel out the net polarization. The 90 per cent upper limit of the polarization fraction for the additional synchrotron jet component is estimated as <10 per cent, <5 per cent, and <5 per cent for polarization angle perpendicular to the disc surface, parallel to the surface, and aligned with the emission reported by INTEGRAL data, respectively. From the 20-180 keV total flux of 2.6 × 10 -8 erg s -1 cm -2, the upper limit of the polarized flux is estimated as < 3 × 10 -9 erg s -1 cm -2.

sted, utgiver, år, opplag, sider
Oxford University Press, 2019
Emneord
accretion, accretion discs, techniques: polarimetric, X-rays: binaries, X-rays: individual (Cygnus X-1)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-248187 (URN)10.1093/mnrasl/sly233 (DOI)000482178200028 ()2-s2.0-85062384117 (Scopus ID)
Merknad

QC 20190412

Tilgjengelig fra: 2019-04-12 Laget: 2019-04-12 Sist oppdatert: 2019-09-05bibliografisk kontrollert
Chauvin, M., Floren, H.-G. -., Friis, M., Jackson, M., Kamae, T., Kataoka, J., . . . Pearce, M. (2018). The PoGO plus view on Crab off-pulse hard X-ray polarization. Monthly notices of the Royal Astronomical Society, 477(1), L45-L49
Åpne denne publikasjonen i ny fane eller vindu >>The PoGO plus view on Crab off-pulse hard X-ray polarization
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2018 (engelsk)Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 477, nr 1, s. L45-L49Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The linear polarization fraction (PF) and angle of the hard X-ray emission from the Crab provide unique insight into high-energy radiation mechanisms, complementing the usual imaging, timing, and spectroscopic approaches. Results have recently been presented by two missions operating in partially overlapping energy bands, PoGO+ (18-160 keV) and AstroSat CZTI (100-380 keV). We previously reported PoGO+ results on the polarization parameters integrated across the light curve and for the entire nebula-dominated off-pulse region. We now introduce finer phase binning, in light of the AstroSat CZTI claim that the PF varies across the off-pulse region. Since both missions are operating in a regime where errors on the reconstructed polarization parameters are non-Gaussian, we adopt a Bayesian approach to compare results from each mission. We find no statistically significant variation in off-pulse polarization parameters, neither when considering the mission data separately nor when they are combined. This supports expectations from standard high-energy emission models.

sted, utgiver, år, opplag, sider
Oxford University Press, 2018
Emneord
instrumentation: polarimeters, methods: statistical
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-241233 (URN)10.1093/mnrasl/sly027 (DOI)000454420400010 ()
Merknad

QC 20190117

Tilgjengelig fra: 2019-01-17 Laget: 2019-01-17 Sist oppdatert: 2019-01-18bibliografisk kontrollert
Organisasjoner