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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tomonori Usuda, Kumiko S. Usuda, Naoyuki Tamura) by email : (please change"_at" to @).

October 26th, Monday, at 11:00 am

" Optical/Infrared emission of magnetars "

Yasuyuki Tanaka


It is widely recognized that magnetars have ultra-strong magnetic fields of 10^14-10^15 Gauss, which is about 100-1000 times stronger than ordinary neutron stars (Thompson & Duncan, 1995; 1996). Magnetars have faint optical/infrared counterparts (Hulleman et al. 2000), but the emission mechanism is poorly understood. The optical/infrared SED shows a peculiar shape, and hence it is difficult to explain by a simple model.
As for the optical emission, the emission region would be magnetosphere, because the emission is pulsed (Kern & Martin, 2002). But the mechanism is still unclear. On the other hand, the infrared emission might come from the fall-back debris disk (Wang et al., 2006).
Pulsation search is essential because, if pulsation is detected, the emission region is restricted within the magnetosphere. Therefore, we can also constrain the emission mechanism. To search for pulsation, we observed AXP 4U 0142+61 with Subaru/IRCS fast readout mode. We obtained a best upper limit of 17% (90% confidence level) for the root-mean-square pulse fraction in K' band. I'll present recent Subaru/IRCS results as well as future plans by FOCAS and other instruments to reveal the emission mechanism.
Thompson & Duncan, 1995, MNRAS
Thompson & Duncan, 1996, ApJ
Hulleman et al., 2000, Nature
Kern & Martin, 2002, Nature
Wang et al., 2006, Nature
Morii et al., 2009, PASJ

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