dc.contributor.author | Barnard, M. | |
dc.contributor.author | Venter, C. | |
dc.contributor.author | Harding, A.K. | |
dc.date.accessioned | 2017-11-02T08:10:15Z | |
dc.date.available | 2017-11-02T08:10:15Z | |
dc.date.issued | 2016 | |
dc.identifier.citation | Barnard, M. et al. 2016. High-energy pulsar light curves in an offset polar cap B-field geometry. 4th Annual Conference on High Energy Astrophysics in Southern Africa, 25-26 Aug 2016, Cape Town, South Africa. Proceedings of science: Article no 042. [https://pos.sissa.it/275/042/] | en_US |
dc.identifier.issn | 1824-8039 (Online) | |
dc.identifier.uri | http://hdl.handle.net/10394/26004 | |
dc.identifier.uri | https://pos.sissa.it/275/042/ | |
dc.identifier.uri | https://pos.sissa.it/275/042/pdf | |
dc.description.abstract | The light curves and spectral properties of more than 200
γ
-ray pulsars have been measured in
unsurpassed detail in the eight years since the launch of the hugely successful
Fermi
Large Area
Telescope (LAT)
γ
-ray mission. We performed geometric pulsar light curve modelling using
static, retarded vacuum, and offset polar cap (PC) dipole
B
-fields (the latter is characterized by a
parameter
ε
), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission
geometries. In addition to constant-emissivity geometric models, we also considered a slot gap
(SG)
E
-field associated with the offset-PC dipole
B
-field and found that its inclusion leads to
qualitatively different light curves. We therefore find that the assumed
B
-field and especially the
E
-field structure, as well as the emission geometry (magnetic inclination and observer angles),
have a great impact on the pulsar’s visibility and its high-energy pulse shape. We compared
our model light curves to the superior-quality
γ
-ray light curve of the Vela pulsar (for energies
>
100 MeV). Our overall optimal light curve fit (with the lowest
χ
2
value) is for the retarded
vacuum dipole field and OG model. We found that smaller values of
ε
are favoured for the
offset-PC dipole field when assuming
constant
emissivity, and larger
ε
values are favoured for
variable
emissivity, but not significantly so. When we increased the relatively low SG
E
-fields
we found improved light curve fits, with the inferred pulsar geometry being closer to best fits from
independent studies in this case. In particular, we found that such a larger SG
E
-field (leading to
variable
emissivity) gives a second overall best fit. This and other indications point to the fact
that the actual
E
-field may be larger than predicted by the SG model | en_US |
dc.language.iso | en | en_US |
dc.publisher | HEASA | en_US |
dc.title | High-energy pulsar light curves in an offset polar cap B-field geometry | en_US |
dc.type | Presentation | en_US |
dc.contributor.researchID | 12006653 - Venter, Christo | |
dc.contributor.researchID | 20574266 - Barnard, Monica | |