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dc.contributor.authorAllafort, A.
dc.contributor.authorVenter, C.
dc.contributor.authorBaldini, L.
dc.contributor.authorBallet, J.
dc.contributor.authorBarbiellini, G.
dc.contributor.authorFermi LAT
dc.date.accessioned2014-04-30T09:56:21Z
dc.date.available2014-04-30T09:56:21Z
dc.date.issued2013
dc.identifier.citationAllafort, A. et al. 2013. PSR J2021+4026 in the gamma cygni region: the first variable γ-ray pulsar seen by the Fermi LAT. Astrophysical journal letters, 777(1): Article no L2. [https://doi.org/10.1088/2041-8205/777/1/L2]en_US
dc.identifier.issn2041-8205
dc.identifier.issn2041-8213 (Online)
dc.identifier.urihttp://hdl.handle.net/10394/10474
dc.identifier.urihttps://doi.org/10.1088/2041-8205/777/1/L2
dc.identifier.urihttp://iopscience.iop.org/2041-8205/777/1/L2/pdf/2041-8205_777_1_L2.pdf
dc.description.abstractLong-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 ± 0.08) × 10−10 erg cm−2 s−1 to (6.86 ± 0.13) × 10−10 erg cm−2 s−1. Simultaneously, the frequency spindown rate increased from (7.8 ± 0.1) × 10−13 Hz s−1 to (8.1 ± 0.1) × 10−13 Hz s−1. Significant (>5σ) changes in the pulse profile and marginal (<3σ) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at γ-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed γ-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.en_US
dc.language.isoenen_US
dc.publisherIOP Publishingen_US
dc.rightsThe Society grants control of the right to reproduce the material to the original authors as long as they are alive. All reproduced material must be properly identified by the citation of the original publication and may carry the indication, "reproduced by permission of the AAS."
dc.rights© 2013. The American Astronomical Society. All rights reserved.
dc.subjectGamma rays: starsen_US
dc.subjectPulsars: individual (PSR J2021+4026)en_US
dc.subjectStars: neutronen_US
dc.titlePSR J2021+4026 in the gamma cygni region: the first variable γ-ray pulsar seen by the Fermi LATen_US
dc.typeArticleen_US
dc.contributor.researchID12006653 - Venter, Christo


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