Change search
ReferencesLink to record
Permanent link

Direct link
Measuring energy dependent polarization in soft gamma-rays using compton scattering in PoGOLite
KTH, School of Engineering Sciences (SCI), Physics.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.ORCID iD: 0000-0002-9769-8016
Show others and affiliations
2007 (English)In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 28, no 3, 327-337 p.Article in journal (Refereed) Published
Abstract [en]

Linear polarization in X-and gamma-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper, we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25-100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 h were simulated, corresponding to a standard and a long duration flight, respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.

Place, publisher, year, edition, pages
Elsevier, 2007. Vol. 28, no 3, 327-337 p.
Keyword [en]
polarization, X-rays, gamma-rays, compton technique, PoGOLite, Geant4, simulations, x-ray, crab-nebula, accretion disks, beam test, hxd-ii, emission, detector, radiation, flux, polarimeter
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-17106DOI: 10.1016/j.astropartphys.2007.06.006ISI: 000250887400007ScopusID: 2-s2.0-35248829556OAI: diva2:335149

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2014-08-29Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Axelsson, MagnusEngdegard, OlleRyde, FelixPearce, MarkKiss, MósziBettolo, C. MariniKlamra, Wlodzimierz
By organisation
PhysicsParticle and Astroparticle Physics
In the same journal
Astroparticle physics
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 97 hits
ReferencesLink to record
Permanent link

Direct link