Optical transients powered by magnetars: Dynamics, LIGHT curves, and transition to the nebular phase

Journal Article · Sun Apr 10 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/821/1/22· OSTI ID:22890086

Wang, Ling-Jun; Xu, Dong; Han, Yan-Hui; Wei, Jian-Yan ^[1]; Wang, S. Q.; Dai, Z. G. ^[2]

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1. Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
2. School of Astronomy and Space Science, Nanjing University, Nanjing (China)

Millisecond magnetars can be formed via several channels: core collapse of massive stars, accretion-induced collapse of white dwarfs (WDs), double WD mergers, double neutron star (NS) mergers, and WD-NS mergers. Because the mass of ejecta from these channels could be quite different, their light curves are also expected to be diverse. We evaluate the dynamic evolution of optical transients powered by millisecond magnetars. We find that the magnetar with a short spin-down timescale converts its rotational energy mostly into the kinetic energy of the transient, while the energy of a magnetar with a long spin-down timescale goes into radiation of the transient. This leads us to speculate that hypernovae could be powered by magnetars with short spin-down timescales. At late times the optical transients will gradually evolve into a nebular phase because of the photospheric recession. We treat the photosphere and nebula separately because their radiation mechanisms are different. In some cases the ejecta could be light enough that the magnetar can accelerate it to a relativistic speed. It is well known that the peak luminosity of a supernova (SN) occurs when the luminosity is equal to the instantaneous energy input rate, as shown by Arnett. We show that photospheric recession and relativistic motion can modify this law. The photospheric recession always leads to a delay of the peak time t{sub pk} relative to the time t{sub ×} at which the SN luminosity equals the instantaneous energy input rate. Relativistic motion, however, may change this result significantly.

• OSTI ID: 22890086
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 821; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
LUMINOSITY
MASS
NEBULAE
NEUTRON STARS
PHOTOSPHERE
RELATIVISTIC RANGE
STAR ACCRETION
SUPERNOVAE
WHITE DWARF STARS