ULX accretion state(s) Roberto Soria Roberto Soria University College London (MSSL) Thanks also in random order to Doug Swartz, Manfred Pakull, Hua Feng, Christian Motch, Luca Zampieri, Fabien Grise’, Jess Broderick, Tim Roberts

Outline Accretion states as mass indicators for ULXs Classifying X-ray properties of ULXs into “states” Mechanical vs radiative states (jets or no jets) Canonical accretion states and state transitions Comptonization-dominated state Slim disk state (High) hard state and where is the standard high-soft state? and where is the standard high-soft state?

1. Canonical BH states (short review) Mostly defined from stellar-mass Galactic BHs Mostly defined from stellar-mass Galactic BHs

State transitions in Cyg X-1 October 1972 harder – non-thermal – radio loud softer – thermal – radio quiet

“Canonical” BH accretion states (From the 1980s… eg, Cyg X-1, GX339-4) Low/Hard state High/Soft state F ( keV) E 1 keV 5 keV Standard disk Radio quiet Jet? Corona? ADAF? CENBOL? Radio loud Very high state Heavily Comptonized disk Radio flaring

Disk + pl Power-law disk (Hao, Soria et al 2010, in preparation) GRS1758 Radio lobes (ATCA 5 GHz)

Canonical state evolution of Galactic BHs Low/hard High/soft Very high Thick flow NoisyJet Thin flow Quiet No jet

ThermalOptically-thick emission from disk Power-law Power-law IC in inner disk or base of outflow (+BMC from outflow?) Truncated disk + ADAF Full disk + jet + corona “Canonical” BH accretion states

High/soft state = disk-blackbody spectrum High/soft state can be used to estimate BH mass

2. Accretion states as indicators of BH mass in ULXs of BH mass in ULXs (where no direct BH mass measurements) (where no direct BH mass measurements)

ULX luminosity function Cartwheel: ~ 1E41 erg/s M82: ~ 1E41 erg/s NGC2276: ~ 1E41 erg/s NGC5775: ~ 8E40 erg/s ARP240: ~ 7E40 erg/s NGC7714: ~ 7E40 erg/s (ESO243-49: ~ 5—8 E41 erg/s) keV isotropic L of the most luminous ULXs Chandra survey of ~200 nearby star-forming galaxies Steepening or cut-off? HMXB extrapolation Number of sources N(>L) Intrinsic 0.5—8 keV Luminosity (10 39 erg/s) 1E391E40 (Swartz et al 2010, in prep) Most or all of these sources consistent with “heavy” stellar BHs up to ~ 70 M sun Different class? IMBHs? D Swartz’s talk today

Let’s take a ULX at L X ~ 1E40 erg/s: What accretion state do we expect? If BH mass > 1,000 M sun we expect to find it in the low/hard state (hot corona, jet) If BH mass ~ 100 – 1,000 M sun we expect to find it in the high/soft state (diskbb, no jet) If BH mass ~ M sun we expect to find it in some kind of very high state (mildly super-Eddington, Comptonized disk) (mildly super-Eddington, Comptonized disk) If BH mass ~ M sun we expect to find it in a new kind of strongly super-Edd state (thick outflows, beamed?) (thick outflows, beamed?)

If BH mass > 1,000 M sun If BH mass ~ 100 – 1,000 M sun If BH mass ~ M sun If BH mass ~ M sun super-stellar stellar Direct collapse of a metal-poor star (Z ~ 0.1) with initial mass ~ 120—150 M sun Core mass up to 70 M sun + fallback + accretion

is there a big difference between: -- “normal” stellar BHs (M ~ 5 – 20 solar) -- “heavy” stellar BHs (M ~ 30 – 100 solar) ? Let’s look at the apparent luminosity If ULXs are stellar (M < 100 M sun ) Accretion rate > 1 Beaming ~ 0.2—0.5 BH mass >~ 10

For a fixed super-Eddington luminosity, the required accretion rate decreases with BH mass For super-Edd ULXs, the expected bright lifetime increases almost exponentially with BH mass

BH mass (M sun ) (M sun / yr) (km) 10 10,000 2E-3 1E E-520, E-6 2, E Assuming beaming ~ 2 (quasi-isotropic), a ULX with L x ~ 1 E 40 erg/s may have:

3. Observational classification of ULX states of ULX states Main problem: spectral coverage only in keV

Typical spectral “states” of ULXs E (keV) LxLx “Soft excess” and break Power-law  ~ “Convex spectrum”

E (keV) LxLx …but very few (if any) diskbb ULXs Typical spectral “states” of ULXs

Power law (  ~ 2) “soft excess” kT ~ 0.15 keV Holmberg II X-1 (L x ~ 2E40 erg/s)

Power-law spectrum Photon index   = 1.6 L x ~ 2 E 40 erg/s M99 X1 (Soria & Wong 2006)

Broken power-law:  = 0.75 below 3 keV,  = 1.4 above 3 keV L x ~ 2.5E40 erg/s NGC 5474 X1 (Swartz & Soria 2010, in prep) NGC 5575 X1 Hard power-law:  = 1.5 L x ~ 7E40 erg/s

Power-law + soft excess  ~ 1.8 L x ~ 2E39 erg/s T in ~ 0.2 keV R in ~ 1500 km Simple power-law  ~ 2.1 L x ~ 5E39 erg/s NGC 4631 X4 NGC 4631 X5 (Soria & Ghosh 2009)

M82 X E 40 (curved) diskbb? 2 E / E /- 0.1 M82 X2 2-3 E Y NGC E /- 0.3 IC342 X1 2 E 40 comp / sd 4-6 E E IC342 X2 1.7 E 40 comp / sd Ho IX 3 E Y 2 E 40 comp / sd 2 E 40 comp / sd 1 E Y 1 E Y Ho II 2 E /- 0.2 Y NGC1313 X1 3 E /- 0.1 Y NGC1313 X2 1-3 E Y sd? 4-6 E Y 4-6 E Y NGC E /- 0.1 Y 7 E /- 0.1 Y 7 E /- 0.1 Y NGC4559 X1 1.5 E Y NGC4559 X2 1 E Y NGC E /- 0.1 NGC E 40 (~1) broken po NGC E /- 0.1 Y (comp) NGC E Y (comp) L  + soft x? curved HS state ULX

NGC5775 X1 7 E / E / E /- 0.2 NGC5775 X2 1 E /- 0.1 NGC1365 X1 3 E / E /- 0.1 Y (curved) 1 E /- 0.1 Y (curved) 5 E /- 0.2 Y 5 E /- 0.2 Y NGC1365 X2 4 E / E / E /- 0.2 M99 2 E /- 0.1 NGC E /- 0.1 Antennae X E Antennae X E Antennae X42 1 E /- 0.1 Antennae X353 E /- 0.5 Antennae X E Antennae X? 1 E /- 0.1 NGC E Y comp NGC E / E 40 (2.6 +/- 0.5) Y comp 4 E 40 (2.6 +/- 0.5) Y comp Cartwheel N E /- 0.2 curved Arp240 7 E /- 0.5 L  + soft x? curved HS state ULX

Most ULXs classified as Power-law + soft excess + downturn at E ~ 5 keV Some have pure power-law spectra (usually hard, photon index < 2) Some have curved spectra: thermal but not standard disk Fitted by slim-disk model (p-free disks) photon trapping & advection, outflows (S Mineshige’s talk) (S Mineshige’s talk)

Power-law + soft excess + downturn at E ~ 5 keV Likely physical interpretation: Inner disk heavily Comptonized – covered or replaced by scattering-dominated region with Te ~ a few keV Standard disk at large radii + Expected from theory when mdot ~ 10 L ~ 2-4 L Edd inner disk becomes effectively thin, hotter (a few keV), scattering dominated,  (scattering) ~ a few

Inner disk heavily Comptonized – covered or replaced by scattering-dominated region with Te ~ a few keV Standard disk at large radii + Because it is the most common ULX state, sometimes called “Ultraluminous state” “Ultraluminous state” (T Roberts, J Gladstone) (T Roberts, J Gladstone)

Standard disk Thermal spectrum Large R c Low T in Low f qpo “reprocessing” region Power-law spectrum Disk and “power-law” components

T in L disk Confusing definitions of ULX temperatures (claims that “ULXs have hot disks” or “ULXs have cool disks”) (Soria 2007) ULXs are here? Or here? Standard disk

T in L disk Standard disk Outer standard disk (soft excess) Confusing definitions of ULX temperatures (claims that “ULXs have hot disks” or “ULXs have cool disks”) Slim disk (Soria 2007) Inner hot region

Slim-disk models suggest L ~ 1 -- a few L Edd “Warm” scattering model suggests L ~ 1 -- a few L Edd Either way, most ULXs should have M ~ 30—100 M sun Hard power-law ULXs still not well understood No clue on BH mass yet

ULXs never lose scattering corona Low/hard High/soft ULXs? Thick flow NoisyJet Thin flow Quiet No jet

X1: Lx = 3E40 (in 2006) 5E39 (in 2007) 5E39 (in 2007)  ~ 1.8 NGC1365 X1, X2 (Soria et al 2007,2009) X2: Lx = 4E40 (in 2006) 1.5E39 (in 2007) 1.5E39 (in 2007)  ~ 1.2 X X X X2 2006

ULXs do not settle into high/soft state (never collapse accretion flow into a thin disk) Saturated Comptonization with T e ~ 5 keV? Decrease of scattering electron Temp Decrease of scattering electron Temp T ~ 100 keV T ~ 10 keV Increase of scattering optical depth Increase of scattering optical depth  ~ 0.1  ~ a few (Galactic BHs) (ULXs) (ULXs) Direct transitions low/hard to ultraluminous state? ULXs may not follow canonical state transitions State transition cycle is driven by 2 parameters: Accretion rate “something else” (ang mom? magnetic energy of the inflow?)

(Belloni 2009) (Zhang et al 1997) Cygnus X-1 never properly switches to a disk-dominated state GX339-4 Cyg X-1

Seyfert 1 galaxy Ark 564 behaves like a ULX (Belloni 2009) GX339-4 Ark 564 Perhaps most AGN are always dominated by scattering corona, not pure disk

4. Radiative and mechanical output ULXs have strong winds (shock-ionized bubble nebulae) ULXs have strong winds (shock-ionized bubble nebulae) Do they also have jets? Do they also have jets?

Do ULXs also have jets? Low/hard High/soft ULXs? Thick flow NoisyJet Thin flow Quiet No jet

ULX bubbles Shock-ionized nebulae with E >~ 1E52 erg and d >~ 100 pc See talks by M Pakull, D Russell NGC1313 X2 Pakull & Mirioni 02, 03 Feng & Kaaret 08 Pakull & Mirioni 02, 03 Grise’ et al 08 IC342 X1 Holmberg IX X1

Non-nuclear radio jet with long-term-avg power ~ 5 E 40 erg/s in a microquasar of NGC7793 Accretion state with jet power ~ maximum ULX luminosities M W Pakull’s talk Pakull, Soria & Motch 2010, Nature, accepted

Summary Accretion states are a BH mass indicator If high/soft state L < L Edd, 100 < M < a few 1000 M sun If VH or slim disk state L < L Edd, M < 100 M sun Most ULXs dominated by p-l or Compt. component (see Hua Feng’s talk) Many have soft excess + p-l + high-energy break (“ULX state”) inner disk modified by scattering-thick region at T ~ a few keV L ~ 1 – a few L Edd, M ~ 30 – 100 M sun Some ULXs have hard power law spectrum Direct evolution between low/hard and “high/hard” state? Very few ULXs are found in the high/soft state (never thin disk) We expect ULX to have jets. Observational challenge to find them. States with jet power ~ rad power

Director’s cut for this talk Two or 3 ULXs are in a weird “supersoft state”, T <~ 0.1 keV Like Galactic SS sources (= nuclear burning WDs) But can a WD reach L ~ 1E39 erg/s Photosphere of massive outflows around a BH? HLX1 in ESO showed a (brief) state transition from power-law dominated to pure thermal True high/soft state? True IMBH? S Farrell’s talk

Why do some BHs lack a thermal dominant state? Different BH mass range? (ULXs 5 times bigger? 100 times?) That should not matter Different BH spin? (why?) That seems very contrived Different magnetic field? Different mode of mass transfer? No. ULXs are Roche Lobe fed, like LMXBs Most Galactic BH transients have low-mass donor stars strongly magnetized accretion flow? strongly magnetized accretion flow? Most ULXs have OB-type donor stars weakly magnetized accretion flow? weakly magnetized accretion flow?

Why do some BHs lack a thermal dominant state? Possible effect of the magnetic field Corona may be produced via irradiated disk evaporation (balance between disk evaporation and condensation…Liu & Taam 2007,2009) Mass evaporation rate scales with thermal conductivity (Meyer-Hofmeister & Meyer 2006) Heat conduction strongly reduced in magnetized plasmas (Chandran & Cowley 1998) Most Galactic BHs have low-mass (magnetic) donor stars (strongly magnetized accretion flow….less evaporation into corona?) Most ULXs and AGN have non-magnetic accretion flows (weakly magnetized accretion flow….more evaporation into corona… …denser, thicker corona… more difficult to collapse it into pure disk state?)

New discovery: ULX & bubble in NGC 5585 (d ~ 7 Mpc) SDSS image

Check with Matonick & Fesen’s H  survey Chandra image 300 pc ULX with Lx = 5 E 39 erg/s

New discovery: NGC 7793 S26 (d ~ 3.9 Mpc) Galex Magellan image (BVR) Liu & Soria (August 09) S26 nebula discovered by Blair & Long 1997 Radio nebula by Pannuti et al 2002 X-ray counterpart identified by Pakull et al 2008

X-ray “triple source” in S26 X-ray core + hot spots Proof of collimated jet

Core (active BH): power-law spectrum Hot spots: thermal spectrum Chandra spectra of core and hot spots in S26 (Pakull, Soria & Motch 2010; Soria et al 2010)

5.5 GHz (ATCA)

9.0 GHz (ATCA)

Radio spectral index

H  map 5.5 GHz contours X-ray core/hot spots FWHM = 250 km/s (~ expansion velocity) Size: 290 x 130 pc Core not detected (2001 CTIO image)

HeII 4686 Nebula emission Core emission: EW ~ 30 A VLT image 2002 (consistent with Wolf-Rayet star)

He II 4686 map with H  contours Shock ionization models suggest v(shock) ~ 275 km/s Density (ISM) ~ 1 cm -3

Zoomed-in view of the S lobe (Magellan image 2009) Core (BH) Optical counterpart: B ~ 23 mag X-ray hot spot Radio hot spot

Energy in the bubble Standard bubble expansion model (self-similar solution, Weaver et al 1977) Mechanical power P j ~ 3 x erg/s Characteristic age ~ 2 x 10 5 yrs Total energy E ~ erg Most of it is thermal energy of protons and ions + work to inflate the bubble against ISM pressure (expanding at v ~ 250 km/s)

Main properties of S26 S26 has the same power as a ULX but in the jet current X-ray luminosity << long-term average jet power S26 nebula is 2 x larger and a few times more powerful than SS433/W50 Collimated jet First evidence of steady collimated jet at accretion rates > Eddington? Ultraluminous X-ray sources Ultrapowerful jet sources P >~ erg/s Radio hot spots & lobes = synchrotron emission X-ray hot spots = thermal plasma emission Bright optical core with HeII 4686 emission (Wolf-Rayet? Accretion disk?)

Comparison between S26 and quasars BH jets/winds ionize a gas bubble of radius P j ~ 3 x erg/s Active for ~ 2 x 10 5 yrs P j ~ a few x erg/s Active for ~ 5 x 10 8 yrs ISM densities ~ 1 cm -3 IGM/ISM densities ~ cm -3 Can shock-heat a bubble of size R ~ 100 pc Can shock-heat a bubble of R ~ a few hundred kpc S26 Typical quasar

Conclusions BHs with super-Eddington accretion can be detected as ULXs (X-ray selected = radiation-dominated by definition!) Most ULXs are likely to be due to super-Edd accretion rather than intermediate-mass BHs. (M82 X1 is perhaps unique exception so far) Many ULXs also have powerful winds (Mechanical power in addition to the X-ray emission) Some super-Eddington BHs may be jet dominated but radiatively faint (S26 in NGC7793) Relative power in the jet and radiation during super-Edd accretion is a fundamental issue to understand quasar feedback

Low-mass and High-mass X-ray binaries Sources in Ellipticals (LMXBs) (Swartz et al 2003) Sources in Spirals/Irr (HMXBs) ULXs HMXBs found in starburst or actively starforming galaxies Luminosity function is steeper for LMXBs Number of HMXBs proportional to star formation rate LMXBs found in elliptical galaxies and old bulges Number of LMXBs proportional to stellar mass of a galaxy

We have discovered the optical counterpart of HLX1 by subtracting the diffuse stellar component of ESO (Soria et al 2010)

Properties of the optical counterpart: R ~ /- 0.3 mag V ~ /- 0.3 mag Two possibilities: Old, massive globular cluster in ESO243 (at 100 Mpc) (like Omega Cen, mass ~ 1E6 solar masses) Foreground M-star in the Galactic Halo (at 1—2 kpc) IMBH in the core of a globular cluster? Neutron star LMXB in the Galactic Halo?

HLX1 Young star formation in ESO (UV emission at 2000 Ang, R contours) But is it related to the HLX1 or just a chance association? Swift/UVOT (Soria et al 2010)

XMM spectra Swift spectrum X-ray spectra are power-law + soft thermal component Thermal component has kT ~ 0.15 keV It could be Accretion disk around an IMBH (at d ~ 100 Mpc) Surface emission from a faint neutron star LMXB in the Galactic Halo (d ~ 1—2 kpc)

Aug 2008 Apr 2010 X-ray lightcurve shows rapid state transitions State transitions of an IMBH accretion disk or intermittent accretion onto a neutron star surface?

Conclusions HLX1 was called a “proven” IMBH We found an optical counterpart to HLX1 From optical and X-ray properties, we argue that there are still 2 possibilities: IMBH in the core of a globular cluster in that distant galaxy in that case, L(0.3—10 keV) ~ 1E41 – 1E42 erg/s Foreground neutron star LMXB in the Galactic Halo in that case, L(0.3—10 keV) ~ 1E32 – 1E33 erg/s (Personally, I would bet my money on the neutron star scenario)

Slim disk Standard disk ADAF (ULX?) (high/soft) (low/hard) Radiative MHD simulations by Ohsuga et al 2009