1. Ultraluminous X-ray Sources Counterparts & Bubbles Manfred Pakull, Fabien Grisé 0bservatoire Astronomique de Strasbourg coll: C. Motch, R. Soria, I. Smith, A. Kubota, T. Tsuru... X-rays from Nearby Galaxies, ESAC Sept 5-7, 2007 :

2. ULX Bubbles

3. LMC X-1 / N159F Only bright XRB that was known to be located in HII region Discovery of first X-ray ionized nebula XIN (HeIII region) Pakull&Angebault 1986

4. SS433 & Cyg X-1 Mechanically inflated bubbles due to XRB jets (or SNR ?) (radio-images) ! note different scale ! Gallo et al 2005 6 pc

5. ULX IC 342 X-1 "Tooth" nebula situated in spiral arm has a diameter of 220pc (Pakull & Mirioni 2002; Roberts et al 2003; Grisé et al 2006 SNR-like spectrum: [SII]/H  =1.2 [OI] 6300/ H  =0.4 X-ray or shock ionization ? Detection of supersonic expansion (see later) from Laurent Mirioni’s thesis

6. ULX in Holmberg IX (M81 X-9) Discovered by Miller 1995: very lum. SNR But variable compact source diameter = 250 pc, away from young star-burst region Contrary to claim by Miller H  /H  is normal, [OI]6300/H  =0.2 Blue star/group near X- ray position (see later)

7. ULX NGC 1313 X-2 Laurent Mirioni’s thesis Previously candidate for galactic neutron star ! location far away (9kpc) from nucleus of N1313 no nearby starburst diameter 400 pc

8. What powers ULX Bubbles ? 1- Photoionized by ULX (or companion star or cluster) ?  XUV luminosity of the source 2a - SNR (HNR) of star that created ULX ? 2b - inflated by wind/jet from ULX (or superbubble inflated by cluster) ?  age, explosion energy E o, or wind/jet luminosity

9. X-ray photoionization

10. Strömgren spheres around O stars Even hottest massive stars (O2,3 V) do not emit substantial He+ Ly cont (h  > 54 eV) i.e., no He++ ions  no nebular HeII 4686 emission very thin skin of ‘warm’ OI atoms i.e., [OI] 6300/Ha < 0.03

11. X-ray ionized nebula Halpern & Grindlay 1980 no sharp Stroemgren spheres; ‘warm’ He++ zone:  HeII 4686 emission ‘warm’ neutrals  strong [OI], [SII]

12. Holmberg II X-1: 2 nd XIN nebular HeII 4686 emission at the position of the ULX (Pakull & Mirioni 2002) ‘Heel’ of Foot nebula

13. Xray ionized nebula in Holmberg II From Laurent Mirioni’s thesis; nebula is density-bound (optically thin) beyond heel Chandra position coincident with He III region structure confirmed by Kaaret et al 04

14. Holmberg II X-1 seen by HST High-resolution imaging with ACS camera on HST by Kaaret et al 2004: Confirmation of nebular morphology (ionisation structure); Counterpart: V=21.9, Mv ~ -5.6

15. HeII 4686 X-ray photon counting X-ray photoionization models (CLOUDY) show good agreement with Zanstra photon counting for 4686 flux; i.e. L HeII 4686  L X if the nebula indeed “sees” the total isotropic X-ray luminosity, i.e. L X ~ 10 40 erg/s no, or only little, X-ray beaming

16. Shock ionization

17. A few elements of shock physics Adiabatic, non-radiative shock ( no B field) n 1 = 4 n 0 ; v 1 = 3/4 v s ; P 1 = 3/4   v s 2 ; T 1 ~ 10 5 K v 100 2 Isothermal, fully radiative shock (no B field) n 2 = M 2 n 0 ; v 2 = v s ; P 2 =   v s 2 ; T 2 =T 0 Dopita & Sutherland 95: v s = 400 km/s Precursor

18. A few elements of shock physics Adiabatic, non-radiative shock ( no B field) n 1 = 4 n 0 ; v 1 = 3/4 v s ; P 1 = 3/4   v s 2 ; T 1 ~ 10 5 K v 100 2 Isothermal, fully radiative shock (no B field) n 2 = M 2 n 0 ; v 2 = v s ; P 2 =   v s 2 ; T 2 =T 0 Dopita & Sutherland 95 v s = 400 km/s Precursor [0I] 6300

19. A few elements of shock physics Adiabatic, non-radiative shock ( no B field) n 1 = 4 n 0 ; v 1 = 3/4 v s ; P 1 = 3/4   v s 2 ; T 1 ~ 10 5 K v 100 2 Isothermal, fully radiative shock (no B field) n 2 = M 2 n 0 ; v 2 = v s ; P 2 =   v s 2 ; T 2 =T 0 For fully radiative shocks a certain fraction of the dissipated energy (‘shock luminosity’ [erg/cm2/s]) L = ½  v s 3 is radiated as H recombination radiation, i.e., L  x L) L  = 7.4x10 -6 v 2 2.4 n 0 erg/cm2/s

20. Shock diagnostics 1 [OIII] 5007/H  ratio as function of schock vel. v s (Dopita et al 1984) 10 3 1.3 5007/ 

21. Shock diagnostics 2: uncomplete shocks OI 6300/H  OIII 5007/ H  HH OIII 5007 100 10 1 0.1 Raymond at al. 1988 high [OIII] 5007/ H  ratios (>6)  uncomplete shocks (not XIN !) high [OI] 6300/ H  ratios (>0.1)  complete shocks Distance from shock 1.0 0.0 Distance from shock

22. Holmberg IX X-1 Nebula shock ionized nebula; breakout towards SE with incomplete shocks SE Subaru B Ha [OIII] B 30 " = 500 pc

23. ULX IC 342 X-1 Roberts et al, MNRAS (2003) INTEGRAL field spectrograph: [OIII]-contours Cont 5000 H  [OIII]-contours Subaru observations (Grisé et al) - ‘high-ionization’ cones are not confirmed 5007 - 5007/ H  varies as function of v s and of completeness ! - i.e., no indication of non-isotropic X-ray emission

24. Kinematics of ULX Nebulae Holm IXNGC1313 X-2 IC 342 X-1 Holm II HH [NII] 6584 V exp = 80 – 150 km/ s

25. Pakull & Mirioni 2002 NGC1313-X2 nebula Size ~ 570 x 400 pc V ~ 100 km/s n ~ 0.2 cm -3 E ~ 1.0 x 10 53 erg E W courtesy D. Wang see Ramsey et al 2006

26. Photo- or shock- ionization ? (with kind regards from the AGN/Liner community) NGC 6946 X-1/MF16, a compact bubble with strong HeII 4686 emission that cannot easily be explained as XIN; i.e., L x (observed) appears much too low; Abolmasov et al. 2006 NGC 1313 X-1: high [OI]6300/Ha ratio in nebular neighbourhood (Pakull&Mirioni 2002) NGC 4485/90: new IR spectral diagnostic proposed by Vazquez et al 2007

27. Spitzer IR diagnostics for six ULXs in NGC 4485/90 Vazquez et al 2007 IR diagnostic diagram: regions around 5/6 ULX appear to have higher ionization than normal HII regions; i.e. AGN-like

28. Energetics of ULX Bubbles Sedov –Taylor (SNR kin Energy E 0, adiabatic) R ~ 12.8 pc (E 51 /n ) 1/5 t 4 2/5 V ~ 500 km/s (E 51 /n ) 1/5 t 4 -3/5 t ~ 6 10 5 yrs R 100 /V 100 E 0 ~ 2 10 52 erg R 100 3 V 100 2 n Wind/jet fed bubble (mech. luminosity L W ) R ~ 26.2 pc (L 36 /n ) 1/5 t 4 3/5 V ~ 15.4 km/s (L 36 /n ) 1/5 t 4 -2/5 t ~ 4 10 5 yrs R 100 /V 100 L W ~ 4 10 39 erg/s R 100 2 V 100 3 n density n from I  = 7.4x10 -6 v 2 2.4 n erg/s/cm2

29. Energetics of ULX Bubbles: SNR Direct application of previous relations yields: t ~ 10 6 yrs (robust); n ~ 0.3 – 10 cm -3 (from H  intensity) E 0 ~10 53 erg  ~100 SNRs in 10 6 yrs (excluded !), or hypernova ( that created ULX) ?

30. Supernovae – Hypernovae Nomoto et al. 2003

31. Energetics of ULX Bubbles winds/jets Direct application of previous relations yields: t ~ 10 6 yrs (robust); E 0 ~10 53 erg  ~100 SNRs in 10 6 yrs (excluded !), or hypernova (->ULX?) or wind/jet fed :  L W ~ few 10 39 erg/s; M dot <10 -6 M sol /yr;  v W,j ~few 0.1 c (mildly relativistic jet velocity); but unlike SS433, jets are not directly observed !

32. Energetics of ULX Bubbles Direct application of previous relations yields: t ~ 10 6 yrs (robust); E 0 ~10 53 erg  ~100 SNRs in 10 6 yrs (excluded !), hypernova (->ULX?) or  L J ~few 10 39 erg/s; M dot <10 -6 M sol /yr;  i.e., we predict v J ~ few 0.1 c, probably dark jets However: much smaller IS density (n~0.01 like in excavated wind- driven superbubbles) would lessen E 0. and L J. v s (optical) not necessarily = v exp of blastwave (X-ray); remember that IS medium is cloudy, like in real SNR

33. ULX Bubbles: possible Misconceptions & Promises High [OIII]5007/Hb ratio does not necessarily imply (beamed) X-ray ionization filamantary HII regions don’t necessarily imply jets If most ULXs do create (wind/jet driven) bubbles: then presently inactive ULX and hypothetical beamed ULX pointed away from us should still be optically visible by their bubbles ; conversely, lack of many large shocked nebulae implies that ULX emission is NOT beamed

34. Inactive ULX bubbles ? If most ULX blow energetic bubbles, than there should exist bubbles that were created by presently inactive ULX, or by beamed ULX that do not point towards us. Search for such objects has revealed only few candidates  little beaming, certainly  /4  HH NGC 1313 X-2 H H NGC 1313 field

35. ULX Optical Counterparts. c.f. talk by Fabien Grisé Optical data have suggested O star optical counterparts  MXRB; holy grail: observe RV curve to derive masses and decide between stellar BHB vs. IMBHs models

36. Holmberg IX X-1 counterpart HeII 4686 Brightest object in cluster has stellar HeII 4686 emission

37. NGC 1313 X-2 Pakull et al. 2005: it is the blue component C1 of double C (Zampieri 2004,06 07) HeII 4686

38. Stellar 4686 emission from ULX Upper: SUBARU spectrum of the 22.8 mag optical counter- part of Hol IX X-1. The stellar 4686 has EW = 9A Lower: ESO-VLT spectrum of 23.4 mag NGC 1313 X-2. Stellar 4686 EW = 10 A. ULX counterparts resemble very luminous (Mv ~ -5) LMXB, i.e. X-ray heated accretion disks (not SS433-like: there EWs several 100 A !!) HeII 4686 Hol IX NGC 1313 X-2 nebular

39. ULX optical counterparts: LMXB – like accretion disks ULXs 1313X-2, HoIX Van Paradijs & McClintock 1994: X-ray heated disks: L v ~L x 1/2 a ~L x 1/2 P orb 2/3 M 1/3 ~  HeII 4686 luminosity ~ L X  high intrinsic L x, no beaming at work here

40. RV variation in NGC1313 X-2 (?) HeII 4686:  RV = 300 km/s in 20 d if confirmed  M x < 50 M  (i.e., not IMBH !) dotted line corresponds to RV of HI gas near XRS

41. What have we learnt ? fancies ULX are IMBH ! …less and less likely ULX are  Blazars ! no: largely isotropic emitters ULX are thermal-  (short) phases of binary evolution ! no: stable nuclear-  transfer Counterparts are O stars ! no: probably accretion disks

42. What have we learnt ? facts A significant fraction of ULX have nebulae, but there are not many X-ray inactive “ULX bubbles”. Some ULX photoionize nebulae allowing (via HeII 4686 photon counting) to estimate total Lx and thus possibly excluding beaming (Hol II, MF16). Extent and supersonic expansion velocity of ULX bubbles allows to measure energetics (>20 x E SNR )  clues to their formation or recent (relativistic) mass-loss history; lifetime > 1 Myr Direct measurements of ULX mass (via RV curve of accretion disk HeII 4686 emission) appears now feasible (but very hard to realize !)

43. FIN