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arXiv · 2209.13493

Investigation of a likely orbital periodicity of Nova Hercules 2021 in X-rays and gamma-rays

Lupin Chun-Che Lin·Jhih-Ling Fan·Chin-Ping Hu·Jumpei Takata·Kwan-Lok Li
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Abstract

We report a detection of a 0.153 days period in the classical nova V1674 Her using the NICER observations taken within a month since the outburst (i.e., about MJD 59405). The X-ray period is consistent with the orbital period previously found in the optical band, strongly suggesting the NICER signal as the X-ray orbital periodicity of the system. A seemingly double-humped profile was obtained by folding the detrended X-ray light curve with the period after removing the rotational X-ray pulsations of the nova. The profile may be caused by occultation by the companion or the accretion disk, possibly indicating a high inclination of the system. The gamma-ray emission of V1674 Her with a significance level > 5 sigma was detected by Fermi-LAT close to its optical peak and the emission faded away within 1 day, which is the shortest duration known for a gamma-ray nova. Folded on 0.153days, a marginal gamma-ray variability can be also seen in the LAT light curve, but without the double-hump feature observed in X-rays. If the gamma-ray modulation is real, its origin is probably different from that observed in the X-ray and optical bands.

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Lupin Chun-Che Lin, Jhih-Ling Fan, Chin-Ping Hu, Jumpei Takata, Kwan-Lok Li. 2022-09-27. Investigation of a likely orbital periodicity of Nova Hercules 2021 in X-rays and gamma-rays. https://doi.org/10.1093/mnrasl%2Fslac117

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