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ULX accretion state(s)

This article explores the canonical accretion states and state transitions in ultraluminous X-ray sources (ULXs). It discusses the classification of X-ray properties, accretion states as indicators of black hole mass, and the spectral coverage of ULX states. The study also includes observations of ULXs in nearby galaxies and their implications for understanding the nature of stellar black holes.

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ULX accretion state(s)

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  1. ULX accretion state(s) 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

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

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

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

  5. “Canonical” BH accretion states (From the 1980s… eg, Cyg X-1, GX339-4) F(0.3-10 keV) Very high state 1 Heavily Comptonized disk Radio flaring High/Soft state 0.1 Standard disk Radio quiet Low/Hard state 0.01 Jet? Corona? ADAF? CENBOL? Radio loud 1 keV 5 keV E

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

  7. Canonical state evolution of Galactic BHs Very high High/soft Thin flow Quiet No jet Thick flow Noisy Jet Low/hard 0 0.5 1

  8. “Canonical” BH accretion states Power-law IC in inner disk or base of outflow (+BMC from outflow?) 1 Thermal Optically-thick emission from disk 0.1 Power-law 0.01 0.001 Truncated disk + ADAF Full disk + jet + corona

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

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

  11. ULX luminosity function Chandra survey of ~200 nearby star-forming galaxies (Swartz et al 2010, in prep) 100 HMXB extrapolation Steepening or cut-off? D Swartz’s talk today 10 Number of sources N(>L) 0.3-10 keV isotropic L of the most luminous ULXs 1 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) 1E39 1E40 Intrinsic 0.5—8 keV Luminosity (1039 erg/s) Most or all of these sources consistent with “heavy” stellar BHs up to ~ 70 Msun Different class? IMBHs?

  12. Let’s take a ULX at LX ~ 1E40 erg/s: What accretion state do we expect? If BH mass > 1,000 Msun we expect to find it in the low/hard state (hot corona, jet) If BH mass ~ 100 – 1,000 Msun we expect to find it in the high/soft state (diskbb, no jet) If BH mass ~ 30 -- 100 Msun we expect to find it in some kind of very high state (mildly super-Eddington, Comptonized disk) If BH mass ~ 10 -- 30 Msun we expect to find it in a new kind of strongly super-Edd state (thick outflows, beamed?)

  13. If BH mass > 1,000 Msun If BH mass ~ 100 – 1,000 Msun super-stellar stellar If BH mass ~ 30 -- 100 Msun Direct collapse of a metal-poor star (Z ~ 0.1) with initial mass ~ 120—150 Msun If BH mass ~ 10 -- 30 Msun Core mass up to 70 Msun + fallback + accretion

  14. If ULXs are stellar (M < 100 Msun ) 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 Accretion rate > 1 Beaming ~ 0.2—0.5 BH mass >~ 10

  15. 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

  16. Assuming beaming ~ 2 (quasi-isotropic), a ULX with Lx ~ 1 E 40 erg/s may have: BH mass (Msun) (km) (Msun / yr)

  17. Observational classification • of ULX states Main problem: spectral coverage only in 0.3-10 keV

  18. Typical spectral “states” of ULXs Lx Power-law G ~ 1.5 - 2 “Convex spectrum” “Soft excess” and break 1 5 10 0.3 E (keV)

  19. Typical spectral “states” of ULXs Lx …but very few (if any) diskbb ULXs 1 5 10 0.3 E (keV)

  20. Holmberg II X-1 (Lx ~ 2E40 erg/s) “soft excess” Power law (G ~ 2) kT ~ 0.15 keV

  21. Holmberg II X-1 (Lx ~ 2E40 erg/s)

  22. M99 X1 Power-law spectrum Photon indexG= 1.6 Lx ~ 2 E 40 erg/s (Soria & Wong 2006)

  23. NGC 5474 X1 (Swartz & Soria 2010, in prep) • Broken power-law: • = 0.75 below 3 keV, G = 1.4 above 3 keV • Lx ~ 2.5E40 erg/s NGC 5575 X1 Hard power-law: G = 1.5 Lx ~ 7E40 erg/s

  24. NGC 4631 X4 Power-law + soft excess G ~ 1.8 Lx ~ 2E39 erg/s Tin ~ 0.2 keV Rin ~ 1500 km (Soria & Ghosh 2009) NGC 4631 X5 Simple power-law G ~ 2.1 Lx ~ 5E39 erg/s

  25. L0.3-10 G ULX + soft x? HS state curved M82 X1 2-10 E 40 (curved) diskbb? 2 E 40 1.2 +/- 0.1 M82 X2 2-3 E 40 1.3-1.5 Y NGC925 2.7 E 40 2.0 +/- 0.3 IC342 X1 2 E 40 comp / sd 4-6 E 39 1.6-1.8 IC342 X2 1.7 E 40 comp / sd Ho IX 3 E 40 1.9 Y 2 E 40 comp / sd 1 E 40 1.6-1.8 Y Ho II 2 E 40 2.5 +/- 0.2 Y NGC1313 X1 3 E 40 2.4 +/- 0.1 Y NGC1313 X2 1-3 E 40 1.7-1.9 Y sd? 4-6 E 39 2.0-2.5 Y NGC5055 2 E 40 2.5 +/- 0.1 Y 7 E 39 2.3 +/- 0.1 Y NGC4559 X1 1.5 E 40 1.8-2.1 Y NGC4559 X2 1 E 40 1.8-2.1 Y NGC1068 1.5 E 40 0.9 +/- 0.1 NGC5474 1.3 E 40 (~1) broken po NGC3628 1 E 40 1.8 +/- 0.1 Y (comp) NGC5408 0.7-1 E 40 2.6-2.7 Y (comp)

  26. ULX G curved HS state L0.3-10 + soft x? NGC5775 X1 7 E 40 1.7 +/- 0.2 1 E 40 1.9 +/- 0.2 NGC5775 X2 1 E 40 1.5 +/- 0.1 NGC1365 X1 3 E 40 1.8 +/- 0.1 1 E 40 1.8 +/- 0.1 Y (curved) 5 E 39 1.8 +/- 0.2 Y NGC1365 X2 4 E 40 1.2 +/- 0.1 1.5 E 39 1.2 +/- 0.2 M99 2 E 40 1.6 +/- 0.1 NGC4579 1.5 E 40 1.9 +/- 0.1 Antennae X11 0.7-2 E 40 1.3-1.8 Antennae X16 0.7-2 E 40 1.1-1.4 Antennae X42 1 E 40 1.7 +/- 0.1 Antennae X35 3 E 40 2.5 +/- 0.5 Antennae X44 1-1.5 E 40 1.6-2.0 Antennae X? 1 E 40 1.2 +/- 0.1 NGC5204 0.7-0.9 E 40 2.1-2.4 Y comp NGC7714 7 E 40 2.1 +/- 0.2 4 E 40 (2.6 +/- 0.5) Y comp Cartwheel N10 4-12 E 40 1.9 +/- 0.2 curved Arp240 7 E 40 1.5 +/- 0.5

  27. Some have pure power-law spectra (usually hard, photon index < 2) Most ULXs classified as Power-law + soft excess + downturn at E ~ 5 keV 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)

  28. 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 LEdd inner disk becomes effectively thin, hotter (a few keV), scattering dominated, t(scattering) ~ a few

  29. 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” (T Roberts, J Gladstone)

  30. Disk and “power-law” components Large Rc Low Tin Low fqpo Standard disk “reprocessing” region Thermal spectrum Power-law spectrum

  31. Ldisk Confusing definitions of ULX temperatures (claims that “ULXs have hot disks” or “ULXs have cool disks”) Or here? ULXs are here? Standard disk (Soria 2007) Tin 0.1 0.5 1

  32. Ldisk Confusing definitions of ULX temperatures (claims that “ULXs have hot disks” or “ULXs have cool disks”) Inner hot region Outer standard disk (soft excess) Slim disk Standard disk (Soria 2007) Tin 0.1 0.5 1

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

  34. ULXs never lose scattering corona ULXs? High/soft Thin flow Quiet No jet Thick flow Noisy Jet Low/hard 0 0.5 1

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

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

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

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

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

  40. Do ULXs also have jets? ULXs? High/soft Thin flow Quiet No jet Thick flow Noisy Jet Low/hard 0 0.5 1

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

  42. 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 Pakull, Soria & Motch 2010, Nature, accepted M W Pakull’s talk

  43. Summary Accretion states are a BH mass indicator L < LEdd, M < 100 Msun If VH or slim disk state If high/soft state L < LEdd, 100 < M < a few 1000 Msun (see Hua Feng’s talk) Most ULXs dominated by p-l or Compt. component 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 LEdd , M ~ 30 – 100 Msun 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

  44. 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 ESO243-49 showed a (brief) state transition from power-law dominated to pure thermal True high/soft state? True IMBH? S Farrell’s talk

  45. 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 mode of mass transfer? No. ULXs are Roche Lobe fed, like LMXBs Different magnetic field? Most Galactic BH transients have low-mass donor stars strongly magnetized accretion flow? Most ULXs have OB-type donor stars weakly magnetized accretion flow?

  46. 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?)

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

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

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

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

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