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1. Magnetars

The First MAXI/GSC View of Galactic Magnetars Yujin E. Nakagawa, Tatehiro Mihara, Mutsumi Sugizaki, Mitsuhiro Kohama, Takayuki Yamamoto, Motoko Suzuki, Masaru Matsuoka (Institute of Physical and Chemical Research),

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1. Magnetars

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  1. The First MAXI/GSC View of Galactic MagnetarsYujin E. Nakagawa, Tatehiro Mihara, Mutsumi Sugizaki, Mitsuhiro Kohama, Takayuki Yamamoto, Motoko Suzuki, Masaru Matsuoka (Institute of Physical and Chemical Research), Nobuyuki Kawai, Mikio Morii, Ryuichi Usui, Kohsuke Sugimori (Tokyo Institute of Technology), Atsumasa Yoshida, Kazutaka Yamaoka, Satoshi Nakahira (Aoyama Gakuin University), Hitoshi Negoro, Motoki Nakajima (Nihon University), Naoki Isobe (Kyoto University) and MAXI Team (E-mail: yujin@crab.riken.jp) Magnetars are strongly magnetized neutron stars with surface magnetic fields of ~1014 G. Based on observational and theoretical studies, 7 soft gamma repeaters and 9 anomalous X-ray pulsars are generally known as the magnetars. Their persistent emission consists of a thermal component (<10 keV), and a hard power law component with a very hard index of 1 (> 10 keV; e.g., Enoto et al. 2010). Some of them presented a flux increasing by a factor of 2-3 accompanied by high burst activities and/or enhanced emission with unusual spectral properties (e.g., [1]). Their continuous monitoring is crucial, since comparisons of properties between low and high flux phases give useful information in order to reveal radiation mechanisms. Thanks to a wide field of view and a better sensitivity than RXTE by a factor of a few in a 2-30 keV range of the MAXI/GSC, it is suitable for this purpose. We analyzed the magnetars, and detected at least AXP 4U 0142+614 (~3 mCrab; >10s) and AXP 1E 1547-5408 (~1.5 mCrab; >14s) using 1 and 4 week data, respectively. We report the first MAXI/GSC view of the magnetars on long-term variability. 1. Magnetars 3. AXP 4U 0142+614 • Highly magnetized neutron stars with Bsurface ~ 1014 G [2]. • Emissions through magnetic energy dissipation. A Long Term Light Curve Burst activity? Black : 32BIT data mode Red : 64BIT data mode (1bin = 7days) X- and g-ray Emitting Magnetars Soft Gamma Repeaters (SGRs) : 7 Objects Anomalous X-ray Pulsars (AXPs) : 9 Objects * Among them, one SGR and one AXP are located in the nearby galaxy. crust (neucleus, e-) Properties of SGRs and AXPs A typical cross-section of magnetars. solid (e-, n) R ~ 10 km r ~ 1015 g cm-3 • Pulse periods of P ~ 2-12 s. • Located in the Galactic plane. • X- and g-ray persistent emissions. • Sporadic burst activities. • Hard X-ray emission at >10 keV. B ~ 1015 G quark? e-, p, n (superfluid) A typical light curve of short bursts Observed with HETE-2 [3]. A spectrum of low fluence short bursts observed with Suzaku [6]. A schematic view of a typical spectrum of persistent emission [4]. SGR 1806-20 SGR 0501+4516 AXP 4U 0142+614 Spectra INTEGRAL [5] Model : 2BB (d = 2.5 kpc) kTLT = 0.58+/-0.04 [keV] RLT = 2.2 (-0.3, +1.4) [km] kTHT = 2.0(-0.3, +0.5) [keV] RHT = 0.14 (-0.05, +0.07) [km] F(2-10keV) = (8.3+/-1.2)×10-11 [erg cm-2 s-1] c2 (d.o.f.) = 86 (82) * The errors of kT and R are 90% C.L., while the erros of the flux are 68% C.L. Black : 32BIT data mode Red : 64BIT data mode Low Temp. BB ~100 ms Low Temp. BB High Temp. BB High Temp. BB Hard X-ray Emission Hard X-ray Emission 100 10 1 Energy (keV) 2. MAXI/GSC Views of Magnetars Images of SGRs in 2-10 keV SGR 0526-66 (in the nearby galaxy) SGR 1806-20 SGR 1900+14 SGR 1627-41 r = 1.5 deg r = 1.5 deg 4. AXP 1E 1547.0-5408 4U 1630-47 64BIT 32BIT 2009/08/15—2010/07/21 2009/08/15—2010/07/27 2009/10/30—2010/07/23 2009/08/15—2010/07/12 A Long Term Light Curve SGR 0501+4516 SGR 1833-0832 SGR 0418+5729 SGR 1801-23 (Candidate) Black : 32BIT data mode Red : 64BIT data mode (1bin = 7days) Burst activity? r = 1.5 deg r = 1.5 deg r = 1.5 deg r = 1.5 deg 2009/08/15—2010/06/24 2009/08/15—2010/07/21 2009/08/15—2010/07/16 2009/08/15—2010/07/17 SGR 2013+34 (Candidate) 32BIT 2009/08/15—2010/07/15 Images of AXPs in 2-10 keV AXP 1E 1048.1-5937 AXP 1E 1841-045 AXP 1E 1547.0-5408 AXP XTE J1810-197 Spectra r = 1.5 deg r = 1.5 deg r = 1.5 deg Model : wabs*(BB+PL) (d = 9 kpc) NH = 3.5 (-1.5, +1.8)×1022 [cm-2] kT = 1.3+/-0.2 [keV] R = 1.3 (-0.2, +0.5) [km] G ~ 0.7 F(2-10keV) = (4.9+/-0.5)×10-11 [erg cm-2 s-1] c2 (d.o.f.) = 115 (92) * The errors of kT and R are 90% C.L., while the erros of the flux are 68% C.L. Black : 32BIT data mode Red : 64BIT data mode ~31s r = 1.5 deg ETA CAR 2009/08/15—2010/06/24 2009/08/15—2010/07/13 2009/08/15—2010/07/19 2009/08/15—2010/07/13 AXP 4U 0142+614 AXP 1E 2259+586 AXP 1RXS J170849.0-400910 AXP AX J1845-0258 r = 1.5 deg r = 1.5 deg ~44s 4U 1708-40 32BIT 2009/08/15—2010/07/21 2009/08/15—2010/11/23 32BIT 2009/08/15—2010/07/15 2009/08/15—2010/07/07 AXP CXOU J010043.1-721134 (in the nearby galaxy) AXP CXOU J164710.2-455216 PSR J1622-4950 (Candidate) CXOU J171405.7-381031 (Candidate) References GX 304+0 [1] Kaneko et al. 2010 [2] Duncan & Thompson 1992 [3] Nakagawa et al. 2007 [4] Nakagawa et al. 2009 [5] Kuiper et al. 2006 [6] Nakagawa et al. 2010 in prep. 32BIT 32BIT 32BIT 32BIT 2009/08/15—2010/11/24 2009/08/15—2010/07/22 2009/08/15—2010/11/24 2009/08/15—2010/11/23

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