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ULXs and Evidence for Two IMBHs in M82 Hua Feng Tsinghua University Collaborators: Phil Kaaret (Iowa), Fengyun Rao (Tsinghua), Jing Jin (Tsinghua) XMM-Newton 2010 Science Workshop, Madrid, Spain M82 – a nearby starburst galaxy Three ULXs in M82 X42.3+59 X41.4+60; X-1 X37.8+54 X41.4+60: 62-day X-ray periodicity Companion’s density for Roche-lobe overflow system = 510-5 g cm-3 a giant or supergiant star (Kaaret et al. 2006; Kaaret & Feng 2007) X41.4+60: Low frequency QPOs Frequency varies from 50-100 mHz (Strohmayer & Mushotzky 2003; Dewangan et al. 2006; Mucciarelli et al. 2006; Feng & Kaaret 2007) Joint Chandra/XMM Observations 2008 Oct 4 2009 Apr 17 2009 Apr 29 Off-axis & subarray configuration to minimize the pileup effect X41.4+60 was observed at the highest flux on 2008 Oct 4. XMM-Newton observations: No QPOs, no timing noise above the Poisson level at > 1mHz Spectral change: from power-law to disk model Chandra spectrum on 2008 Oct 4 Multicolor accretion disk model 2/dof = 67.8/70 Power-law model with pileup 2/dof = 201.8/71 Power-law model without pileup 2/dof = 102.1/70 Ldisk T4 X41.4+60: thermal dominant state • No QPOs and low timing noise • Disk model with L T4 • Emission States – hard, thermal dominant, steep power-law (Remillard & McClintock 2006) Corona Disk Thermal dominant state (Gierlinski & Done 2004) • L T4: constant inner radius • The accretion disk extends all the way to ISCO • RISCO depends on MBH and Spin Fitting with a fully relativistic disk model M = 200-800 Msun a* > 0.93 i > 60 IMBH with nearly maximal spinning ! Hard to Thermal transition Relatively low flux Hard power-law spectrum QPOs + flat-top PSD Three ULXs in M82 X42.3+59 X41.4+60; X-1 X37.8+54 X42.3+59: sometimes brighter than X41.4+60 XMM-Newton Chandra 15 radius X42.3+59 X41.4+60 X42.3+59: A transient ULX Chandra Chandra X42.3+59: A transient ULX (Feng & Kaaret 2007) > 1000 Stellar mass black hole with massive donor: stable accretion disk IMBH: unstable accretion disk (Kalogera et al. 2004) X42.3+59: discovery of QPOs • Confirmed by simultaneous Chandra/XMM observations • Narrow range: 3-4 mHz • Broad & strong • No red noise (down to QPO / 100) • Only appear when LX > ~1040 erg/s (Feng, Rao, & Kaaret 2010) Three Types of LFQPOs XTE J1859+226 GX 339-4; Type B QPOs (Belloni et al. 2005) (Casella et al. 2004) X42.3 QPOs are of Type A or B Type A/B QPOs: narrow frequency range (Casella et al. 2005) X42.3 QPOs: 103 times lower than in stellar mass BHs X42.3: 104 solar masses; companion star not needed Three ULXs in M82 X42.3+59 X41.4+60; X-1 X37.8+54 X-ray dips during one outburst Source spectrum: soft excess + hard component Soft excess: blackbody emission from a massive outflow (King 2004; Poutanen et al. 2007) Summary • X41.4+60: ~102 solar masses – hard state • Orbital period of 62 days • Low frequency QPOs and strong variability • Power-law spectrum with = 1.7 – thermal dominant state • outbursts • No QPOs, low timing noise • Thermal spectrum, L T4 • X42.3+59: ~104 solar masses – Low frequency type A/B QPOs around 3-4 mHz – 103 lower than the frequency of the same type QPOs in stellar mass black holes • X37.8+54: tens of solar masses – A thrid, new ULX in M82 – Stellar BH with massive outflow Feng & Kaaret 2010 Feng, Rao, & Kaaret 2010 Jin, Feng, & Kaaret 2010