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Spectral transition of Spectral transition of ultraluminous X-ray source, ultraluminous X-ray source,

NGC 2403 SRC3NGC 2403 SRC3

N. Isobe (RIKEN, N. Isobe (RIKEN, SuzakuSuzaku Help Desk) Help Desk)andand

Suzaku SWG team of NGC 2403Suzaku SWG team of NGC 2403

K. Makishima (RIKEN/U. Tokyo), M. Kawaharada, A. Senda (RIKEN), K. Makishima (RIKEN/U. Tokyo), M. Kawaharada, A. Senda (RIKEN), H. Takahashi, T. Mizuno (Hirishima U.), R. Miyawaki (U. Tokyo),H. Takahashi, T. Mizuno (Hirishima U.), R. Miyawaki (U. Tokyo),

T. Yoshida (Tokyo Univ of Schience), R. Mushotzky (GSFC/NASA)T. Yoshida (Tokyo Univ of Schience), R. Mushotzky (GSFC/NASA)

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Ultraluminous X-ray Sources (ULXs)Ultraluminous X-ray Sources (ULXs)X-ray point sources with a luminosity of X-ray point sources with a luminosity of LL > >

> 10> 103939 ergs s ergs s-1-1, frequently found in nearby n, frequently found in nearby normal galaxies ormal galaxies (Fabbiano et al. 1989)(Fabbiano et al. 1989)

Promising candidate of Promising candidate of intermediate mass bintermediate mass black holeslack holes with a mass of with a mass of M M >> 10 >> 10 MM◎◎, (, (MM ◎ ◎is the solar mass). is the solar mass). (e.g. Makishima et al. 2000)(e.g. Makishima et al. 2000)

Two spectral states Two spectral states (e.g., Kubota et al. 2001)(e.g., Kubota et al. 2001)

Multi-color disk (Multi-color disk (MCDMCD) and Power Law () and Power Law (PLPL) ) Important sources to study black holes at Important sources to study black holes at hihi

gh accretion rategh accretion rate..

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SuzSuzakuaku 55thth Japanese X-ray observatory, launch Japanese X-ray observatory, launched in June 2005 ed in June 2005 (Mitsuda et al. 2007)(Mitsuda et al. 2007)

Two instruments Two instruments X-ray Imaging Spectrometer (XIS)X-ray Imaging Spectrometer (XIS)

3 FI and 1 BI CCDs3 FI and 1 BI CCDs 0.2 – 12 keV0.2 – 12 keV

Hard X-ray Detector (HXD)Hard X-ray Detector (HXD) PIN : 10 – 70 keVPIN : 10 – 70 keV GSO : 40 – 600 keVGSO : 40 – 600 keV

Advantages Advantages Low and stable backgroundLow and stable background Good energy resolutionGood energy resolution High sensitivityHigh sensitivity Wide energy bandWide energy band

Results on ULXsResults on ULXs NGC 1313 NGC 1313 (Mizuno et al, 2007)(Mizuno et al, 2007)

SuzakuSuzaku J1305-4931 J1305-4931 (Isobe et al. 2008)(Isobe et al. 2008)

Suzaku

XIS HXD

@ Terada (Saitama U.)

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NGC 2403NGC 2403 Spiral galaxy (SABcd) at a dSpiral galaxy (SABcd) at a d

istance of 3.2 ± 0.4 Mpc istance of 3.2 ± 0.4 Mpc (Free(Freedman & Madore 1988)dman & Madore 1988)

Several bright X-ray sourceSeveral bright X-ray sources, including ULX. s, including ULX. (Fabianno & Tri(Fabianno & Trinchieri 1987)nchieri 1987)

SuzakuSuzaku observation on Mar observation on March 16ch 16thth, 2006 during SWG p, 2006 during SWG phasehase

ASCAASCA observation in 1997 observation in 1997 (Kotoku et al.,1999)(Kotoku et al.,1999)

Discovery of a supernova SDiscovery of a supernova SN2004dj motivated a series N2004dj motivated a series of of ChandraChandra, XMM-, XMM-Newton Newton oobservationsbservations

Optical image (DSS)

Suzaku XIS image (0.5 – 10 keV)

SRC3

SRC5

4 arcmin = 3.7 kpc

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SuzakuSuzaku Spectrum of SRC3 Spectrum of SRC3

SuzakuSuzaku XIS spectrum of XIS spectrum of NGC 2403 SRC 3NGC 2403 SRC 3 is successfully described wiis successfully described wi

th multi-temperature black th multi-temperature black body emission from accretibody emission from accretion disk (Multi-color disk moon disk (Multi-color disk model; MCD).del; MCD).

TTinin = 1.09 ± 0.03 keV = 1.09 ± 0.03 keV RRinin = 116.9 + 5.9 – 5.5 km = 116.9 + 5.9 – 5.5 km LLbolbol = 1.75 x 10 = 1.75 x 103939 ergs s ergs s-1-1

is not fitted with a PL modeis not fitted with a PL model.l.

XIS 0+2+3 (FI)XIS 1 (BI)

MCD　 (2 = 296.5/334 )

PL (2 = 585.3 / 334)

MCD

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Relation betweenRelation between L Lbolbol and and TTinin

SRC5

SRC3

(Kotoku et al. 2000, Makishima et al. 2000, Isobe et al. 2007 and reference therein)

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Spectral transition of SRC3Spectral transition of SRC3 Only the Only the ChandraChandra data data obtained in De obtained in De

cember, 2004 showed the PL-like specember, 2004 showed the PL-like spectrum.ctrum. = 2.37 ± 0.07= 2.37 ± 0.07

The X-ray flux of the observation is sliThe X-ray flux of the observation is slightly smaller than the ghtly smaller than the SuzakuSuzaku observ observation by 15 %.ation by 15 %.

Spectral transition between the MCD-Spectral transition between the MCD-like and the PL-like states is like and the PL-like states is Frequently observed in Galactic blFrequently observed in Galactic bl

ack holes.ack holes. Observed in some well-studied UObserved in some well-studied U

LXs. (e.g. Kubota et al. 2001) LXs. (e.g. Kubota et al. 2001)

Ratio to the best-fit MCD model to Suzaku data

Suzaku (2006 May)

Chandra (2004 Aug.)

Chandra (2004 Dec.)

Newton (2004 Sep.)

Chandra (2004 Aug.)

Chandra (2004 Dec.)

Newton (2004 Sep.)

MCDMCD

MCDPL

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Spectral states of black holesSpectral states of black holes

1 10 100Energy [keV]

Lbol / LEdd

1

0.1

0.01 Low/Hard state(PL)

High/Soft state(MCD)

Very high state(PL-like)

Slim disk state(MCD-like)

Suzaku XISChandra/Newton

Spectral transition of NGC 2403 SRC 3Slim disk state

⇔Very high state

< 2

2< < 3

(e.g. Kubota et al. 2004)

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Slim disk scenario for SRC 3Slim disk scenario for SRC 3

Standard disk (in MCD)Standard disk (in MCD) Radial temperature profileRadial temperature profile

TT ∝ ∝ r r -0.75-0.75

Slim diskSlim disk Advection and/or photon trAdvection and/or photon tr

apping become important.apping become important.

⇒ ⇒ Flat profile Flat profile (Watarai et al. 2000)(Watarai et al. 2000)

TT ∝ ∝ r r ––pp with 0.5 < with 0.5 < pp < 0.75 < 0.75

(p-free disk model; (p-free disk model; Mineshige et aMineshige et a

l. 1994, Vierdayanti et al. 2006l. 1994, Vierdayanti et al. 2006))

MCD : p = 0.75(Standard disk)

Limit in Slim disk state

p = 0.5

Summary of p-free disk fitting

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SummarySummary We examined the spectral variation of the ULX, NGC 240We examined the spectral variation of the ULX, NGC 240

3, in nearly 10 years, using 3, in nearly 10 years, using ASCAASCA, , SuzakuSuzaku, , ChandraChandra and and XMM-NewtonXMM-Newton. .

NGC 2403 SRC3 showed the NGC 2403 SRC3 showed the MCD-like spectraMCD-like spectra, except fo, except for one r one ChandraChandra observation. observation. TTinin = 1.09 ± 0.03 keV = 1.09 ± 0.03 keV RRinin = 116.9 + 5.9 – 5.5 km = 116.9 + 5.9 – 5.5 km 　　 (in the (in the SuzakuSuzaku Observation) Observation) LLbolbol = 1.75 x 10 = 1.75 x 103939 ergs s ergs s-1-1

We found the We found the transition to the PL-like spectrumtransition to the PL-like spectrum in the Cha in the Chandra observation, conducted on December 2004, with the ndra observation, conducted on December 2004, with the flux about 10 % lower than the other observations.flux about 10 % lower than the other observations. = 2.37 ± 0.07= 2.37 ± 0.07

The spectral transition of NGC 2403 SRC 3 can be naturaThe spectral transition of NGC 2403 SRC 3 can be naturally explained to be a transition between lly explained to be a transition between Very High state Very High state (PL-like) and slim disk state (MCD-like).(PL-like) and slim disk state (MCD-like).

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ChandraChandra image image

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Spectral transition of SRC 3Spectral transition of SRC 3

Chandra ACIS S5

MCD (2 = 194.8/123)

PL (2 = 110.7/123)

PL