Kazutaka Yamaoka (Aoyama Gakuin University),

On behalf of the MAXI and Suzaku team

Outline Coordinated MAXI and Suzaku observationsSuzaku observations of XTE J1752-223 with MAXI results Please also see Nakahira et al. P-1 (MAXI) and Koyama et al.

P-2 (Suzaku)

Very preliminary results from Suzaku observations of MAXI J1659-152Summary

Coordinated MAXI and Suzaku observations High sensitive all-sky X-ray survery with MAXI 　 15mCrab@day

+ Wide-band and high-sensitive X-ray observations with Suzaku

Very powerful collaboration for studying X-ray transients.

　 e.x. Discovery of a new MAXI source Identify the nature of the source with Suzaku

Suzaku ToO Observations by MAXI team have been approved since AO5.

4 Suzaku ToO observations triggered by MAXI team so far

Source Category Obs. Date Exposure

Related information

V 0332+53

X-ray binary pulsar

Feb 16, 2010 32 ksec

XTE J1752-223

Black hole candidate

Feb 24-25, 2010

40 ksec Also proposed from the US side

GX 304-1

X-ray binary pulsar

Aug. 13, 2010 23 ksec Discovery of cyclotron features (Yamamoto et al .P-13)

MAXI J1659-152

Black hole candidate

Sep 29, 30, Oct. 1-2, 2010 (3 times)

16, 24, 31 ksec

BHC XTE J1752-223 Discovered by the RXTE/PCA Galactic-Center scan observations (Markwardt et al. 2009) MAXI confirms this new transient and monitor the entire outburst. (Nakahira et al. 2010 PASJ, Nakahira et al. P-1 ) Identified as a black hole candidate by RXTE. Displayed Hard –to-soft, and Soft-to-hardtransitions. Bipolar plasma ejection events, i.e. jets, were detected.

The distance, the black hole mass, and the inclination angle are still unknown.

XTEJ1752-223

Suzaku observation of XTE J1752-223 Details of observations

ObservationDate 　 2010-02-24 04:58:00　　　　　　　　　–　 2010-02-25 04:27:24 (UT) Total exposure 41 ksec ＸＩＳ Exposure 0.5 ksec (XIS 1), 　　　　　　　　　　　 6.1 ksec (XIS 0,3) Observation direction HXD nominalＸＩＳ mode

Full window 0.1s burst option (XIS 1) 　　 　 1/4 window 0.3s burst option (XIS 0.3) 　

Suzaku observed “High/Soft state”

Suzakuobservation

Low/hard　　　　

High/Soft

The Suzaku/XIS light curve XIS count rate : 0.5-10 keVDuring the obs.,

the XIS intensity and spectral shape do not change significantly.

Produce the XIS spectra by averaging over the whole observation.

Hardness ratio: 　 2-10 keV/0.5-2 keV

About 1 day

Suzaku wide-band spectra XIS1

XIS0+3 HXD/PINHXD/GSO

Detected up to ~ 50 keV with HXD/PIN. The HXD/GSO could detect no significant signals above 50 keV.

Energy 　 (keV)

Detection llimit

Modeling with the Multi-Color Disk model (Mitsuda et al. 1984) plus a power-law (χ2 /dof = 508/339)

HXD/PIN

XIS1XIS0+3

MCD modelTin=0.53+/-0.01 keVRin(cos i)1/2 /(D/10 kpc) = 117.9+/-2.0 km

Power lawΓ=2.34+/-0.07

MCDPower law

νFν spectra

Spectral modeling of wide-band spectra

Results from RXTE and MAXI observations

Innermost temp. Tin (keV)

Innermost

radius Rin

Photon index Γ

Flux 3-50 keV

RXTE and MAXI monitoring observations show that the innermost radii are almost constant at 110~130 km, which is independent of X-ray flux. This value is almost consistent with Suzaku measured one.

Can estimate the black hole mass

Estimation of the black hole massSuzaku measured innermost radius: 　　　 Rin(cosi)1/2 /(D/10 kpc) =117.9±2.0 (km) rin=ξκ2Rin (Kubota et al. 1998)

κ=1.7 ： Spectral hardening factor (Shimura & Takahara 1995)

ξ=0.412: boundary condition near the inner edge of the disk

　　 = 198.5±3.4 　　　　　　 x (D/10 kpc) x (cosi /cos 60°)-1/2 　（ km)If we assume a Schwartzchild black hole, the innermost stable circular orbit (ISCO): 3Rs=6GM/c2=8.86 (M/M◎) km

BH mass : M = 22.4±0.4 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　　　　　　 x (D/10 kpc) x (cosi /cos 60°)-1/2 (M◎) Precise determination of a distance and an inclination angle will be desired in a future.

　　　

BHC MAXI J1659-152 The Swift/BAT discovered a new source as GRB 100925A on Sep. 25, 2010 (Mangano et al. GCN #11296). The MAXI/GSC independently found a new X-ray source

as MAXI J1659-152 (Negoro et al. Atel #2873).RXTE follow-up observations reveal it as a black hole candidate. (Kalamkar et al. Atel # 2881)Many multi-wavelength observations were performed due to the Swift/BAT GRB trigger and its source location well above the Galactic plane.

Sep. 25

Sep. 24

MAXI J1659-152

Suzaku observations of MAXI J1659-152

Details of the three observations• Observation Dates 　 Sep. 29, 30, Oct. 1-2, 2010

• XIS0/HXD exposure 1.6 k / 16.3 ksec 15.0 k / 23.5 ksec 4.9 k / 30.7 ksec

•Observation direction HXD nominal

•ＸＩＳ mode ¼ window with no burst option (Sep. 29, 30)

0.3s burst option (Oct 1-2) 　

Suzaku observed a rare

“intermediate state” in the rising phase.

MAXI/GSC Hardness-Intensity diagram

High/Soft

Low/hard　　　　

Preliminary results of Suzaku data QPO features at about 3 Hz are detected in the HXD/PIN data for all the three observations.

The XIS+PIN spectra are explained by the disk blackbody plus power law with an exponential cutoff.

The intermediate observations with Suzaku might reveal a disk-corona-jet geometry around the BH during the state transition.

LF QPOCut-off

Summary MAXI and Suzaku coordinated observations since

AO5 Four sources so far: V0332+53 、 XTEJ1752-223 、 GX304-1, and MAXI J1659-152

Suzaku observation of XTE J1752-223 High/Soft state 　 The 1-50 keV spectra are explained by MCD model plus power

law. Suzaku and RXTE observation suggests a constancy of innermost

radius at 120~130 km Estimation of the black hole mass　 　　　　　　　　　　　　　　 22.4+/-0.4 M◎ for i=60°, D=10 kpc Further examination of the “ disk-line feature”

Suzaku observation of MAXI J1659-152 Intermediate state in the rising phase. 0.6-70 keV spectra are explained by MCD model plus cutoff

power law. The QPO features are present in the HXD/PIN power spectrum.

Presence of a disk line ？Reis et al. (2010) suggested a presence of a disk line using the same Suzaku data. They fitted the continuum using the1.3-4.5, 8.0-10.0, 20-45 keV data.

We can reproduce the same feature with the same procedures, but using all the energy bands, we can see a reflection feature instead.

SuzakuRXTE/PCA

Pile-up effects

r<30’’

30’’<r<60’’

60’’<r<90’’

For bright sources, the XIS spectra were affected by pile-up effects 。In the central region, the spectra get harder.

Need to exclude at least the region with r<60``

PHA Ratio to the spectra in the Outer regions(90``<r<120``)

MAXI light curve of V0332+53Suzaku observation

XIS spectra of V0332+53

NH= 1.55 (-0.17,+021)x1022 cm-2 α= 1.07(-0.09, +0.10) Flux 2-10 keV 6.4x10-12 erg/cm2/s ~0.3 mCrab (Crab:2.2x10-8)

χ2/dof = 320/325

The spectrum is rather hard photon index ~1