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 23 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; >10) and AXP 1E 1547-5408 (~1.5 mCrab; >14) using 1 and 4 week data, respectively. We report the first MAXI/GSC view of the magnetars on long-term variability.

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)

1. Magnetars

2. MAXI/GSC Views of Magnetars

3. AXP 4U 0142+614

4. AXP 1E 1547.0-5408

References

Highly magnetized neutron stars with Bsurface ~ 1014 G [2].Emissions through magnetic energy dissipation.

A typical cross-section of magnetars.

B ~ 1015 G

crust(neucleus, e)

solid(e, n)

e, p,n (superfluid)

quark?

R ~ 10 km ~ 1015 g cm3

X- and -ray Emitting Magnetars① Soft Gamma Repeaters (SGRs) : 7 Objects② Anomalous X-ray Pulsars (AXPs) : 9 ObjectsProperties of SGRs and AXPsPulse periods of P ~ 212 s.Located in the Galactic plane.X- and -ray persistent emissions.Sporadic burst activities.Hard X-ray emission at >10 keV.

1 10 100Energy (keV)

11

Low Temp. BB

High Temp. BB

Hard X-ray Emission

INTEGRAL [5]

Low Temp. BB

High Temp. BB

Hard X-ray Emission

~100 ms

SGR 1806-20

A typical light curve of short burstsObserved with HETE-2 [3].

A schematic view of a typicalspectrum of persistent emission [4].

A spectrum of low fluence short burstsobserved with Suzaku [6].

[1] Kaneko et al. 2010[2] Duncan & Thompson 1992[3] Nakagawa et al. 2007

AXP 4U 0142+614 SGR 0501+4516

SGR 0501+4516

r = 1.5 deg

SGR 0418+5729

r = 1.5 degr = 1.5 deg

SGR 1833-0832

SGR 1806-20

r = 1.5 deg

2009/08/15—2010/06/24

r = 1.5 deg

SGR 0526-66(in the nearby galaxy)

SGR 1801-23(Candidate)

r = 1.5 deg

2009/08/15—2010/07/12

2009/08/15—2010/07/172009/08/15—2010/07/16

2009/08/15—2010/07/21

2009/08/15—2010/07/21

Images of SGRs in 2-10 keV

Images of AXPs in 2-10 keV

SGR 1900+14 SGR 1627-41

SGR 2013+34(Candidate)

AXP 1RXS J170849.0-400910

AXP 1E 1048.1-5937 AXP 1E 1547.0-5408

r = 1.5 deg

r = 1.5 deg

r = 1.5 deg

AXP XTE J1810-197 AXP 1E 1841-045

r = 1.5 deg

AXP 4U 0142+614

r = 1.5 deg

AXP 1E 2259+586

r = 1.5 deg

~31

~44

2009/08/15—2010/07/19

2009/08/15—2010/07/21

2009/08/15—2010/07/132009/08/15—2010/07/13

2009/08/15—2010/07/07

2009/08/15—2010/06/24

AXP AX J1845-0258

AXP CXOU J164710.2-455216 AXP CXOU J010043.1-721134

(in the nearby galaxy)PSR J1622-4950

(Candidate)CXOU J171405.7-381031

(Candidate)

32BIT

32BIT

ETA CAR

32BIT

4U 1630-47

32BIT

4U 1708-40

32BIT

32BIT

GX 304+0

2009/08/15—2010/07/15 2009/08/15—2010/11/23

2009/08/15—2010/07/22

2009/08/15—2010/07/27

2009/08/15—2010/07/15

32BIT2009/08/15—2010/11/242009/08/15—2010/11/24 32BIT2009/08/15—2010/11/23

64BIT2009/10/30—2010/07/23

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]

2 (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.

A Long Term Light Curve

Spectra

Black : 32BIT data modeRed : 64BIT data mode

A Long Term Light Curve

Black : 32BIT data modeRed : 64BIT data mode(1bin = 7days)

[4] Nakagawa et al. 2009[5] Kuiper et al. 2006[6] Nakagawa et al. 2010 in prep.

SpectraBlack : 32BIT data modeRed : 64BIT data mode

Black : 32BIT data modeRed : 64BIT data mode(1bin = 7days)

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] ~ 0.7

F(2-10keV) = (4.9+/-0.5)×10-11 [erg cm-2 s-1]

2 (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.

Burst activity?

Burst activity?

* Among them, one SGR and one AXP are located in the nearby galaxy.