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
:
ULX BubblesULX Bubbles
LMC X-1 / N159F LMC X-1 / N159F
Only bright XRB thatwas known to be located in HII region
Discovery of firstX-ray ionized nebulaXIN (HeIII region)Pakull&Angebault 1986
SS433 & Cyg X-1
Mechanically inflatedbubbles due to XRB jets (or SNR ?)
(radio-images)
! note different scale !Gallo et al 2005
6 pc
ULX IC 342 X-1ULX 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
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)
ULX NGC 1313 X-2
Laurent Mirioni’s thesis
Previously candidate forgalactic neutron star !
location far away (9kpc)from nucleus of N1313 no nearby starburst
diameter 400 pc
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 Eo, or wind/jet
luminosity
X-ray photoionizationX-ray photoionization
Strömgren spheres around O stars
Even hottest massive stars (O2,3 V) do notemit substantial He+Ly cont (h> 54 eV)
i.e., no He++ ions no nebular HeII4686 emission
very thin skin of ‘warm’ OI atoms i.e., [OI]6300/Ha < 0.03
X-ray ionized nebula
Halpern & Grindlay 1980
no sharp Stroemgren spheres; ‘warm’ He++ zone: HeII4686 emission‘warm’ neutrals strong [OI] , [SII]
Holmberg II X-1:
2nd XIN
nebular HeII 4686 emission at the position of the ULX (Pakull & Mirioni 2002)
‘Heel’ of Foot nebula
Xray ionized nebula in Holmberg Xray ionized nebula in Holmberg IIII
From Laurent Mirioni’s thesis; nebula is density-bound (optically thin) beyond heel
Chandra position coincident withHe III regionHe III region
structure confirmed by Kaaret et al 04
Holmberg II X-1 seen by HSTHolmberg II X-1 seen by HST
High-resolution imaging with ACS camera on HST byKaaret et al 2004:
Confirmation of nebular morphology (ionisation structure);
Counterpart: V=21.9,Mv ~ -5.6
HeII 4686 X-ray photon counting
X-ray photoionization models (CLOUDY) show good agreement with
Zanstra photon counting for 4686 flux; i.e.
LHeII4686 LX
if the nebula indeed “sees” the total isotropic X-ray luminosity,
i.e. LX ~ 1040 erg/s no, or only little, X-ray beaming
Shock ionization
A few elements of shock physics A few elements of shock physics Adiabatic, non-radiative shock ( no B field)n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 vs
2; T1 ~ 105 K v100
2
Isothermal, fully radiative shock (no B field)n2 = M2 n0; v2 = vs; P2 = vs
2 ; T2=T0
Dopita &Sutherland 95:vs = 400 km/s
Precursor
A few elements of shock physics A few elements of shock physics Adiabatic, non-radiative shock ( no B field)n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 vs
2; T1 ~ 105 K v100
2
Isothermal, fully radiative shock (no B field)n2 = M2 n0; v2 = vs; P2 = vs
2 ; T2=T0
Dopita &Sutherland 95vs = 400 km/s
Precursor
[0I] 6300
A few elements of shock physics A few elements of shock physics Adiabatic, non-radiative shock ( no B field)n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 vs
2; T1 ~ 105 K v100
2
Isothermal, fully radiative shock (no B field)n2 = M2 n0; v2 = vs; P2 = vs
2 ; T2=T0
For fully radiative shocks a certain fraction of the dissipated energy (‘shock luminosity’ [erg/cm2/s]) L = ½ vs
3 is radiated as H recombination radiation, i.e., Lx L)
L = 7.4x10-6 v22.4 n0 erg/cm2/s
Shock diagnostics Shock diagnostics 11
[OIII]5007/Hratio as functionof schock vel. vs (Dopita et al 1984)
10
3
1
.3
5007/
Shock diagnostics 2: uncomplete shocksShock diagnostics 2: uncomplete shocks
OI6300/H
OIII5007/ H
H
OIII5007100
10
1
0.1
Raymondat al. 1988
high[OIII]5007/ H ratios (>6) uncomplete shocks (not XIN !)
high [OI]6300/ Hratios (>0.1) complete shocks
Distance from shock
1.0
0.0
Distance from shock
Holmberg IX X-1 NebulaHolmberg IX X-1 Nebula
shock ionized nebula;breakout towards SE with incomplete shocks
SE
Subaru
Ha [OIII] BB30 "
=
500 pc
ULX IC 342 X-1ULX IC 342 X-1
Roberts et al, MNRAS (2003)
INTEGRAL field spectrograph:Cont5000 H [OIII]-contours[OIII]-contours
Subaru observations (Grisé et al)
- ‘high-ionization’ cones are not confirmed- 50075007/ H varies as function of vs and of
completeness !- i.e., no indication of non-isotropic X-ray emission
Kinematics of ULX NebulaeKinematics of ULX Nebulae
Holm IX NGC1313 X-2
IC 342 X-1 Holm II
H
[NII] 6584
Vexp = 80 – 150
km/s
Pakull & Mirioni 2002NGC1313-X2 nebula
• Size ~ 570 x 400 pc• V ~ 100 km/s• n ~ 0.2 cm-3
• E ~ 1.0 x 1053 erg
E
W
courtesy D. Wangsee Ramsey et al 2006
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., Lx(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
Spitzer IR diagnostics for six ULXs in NGC 4485/90
Vazquez et al 2007IR diagnostic diagram:
regions around 5/6ULX appear to havehigher ionization thannormal HII regions;i.e. AGN-like
Energetics of ULX Bubbles Energetics of ULX Bubbles Sedov –Taylor (SNR kin Energy E0, adiabatic)
• R ~ 12.8 pc (E51/n )1/5 t42/5
• V ~ 500 km/s (E51/n )1/5 t4-3/5
• t ~ 6 105 yrs R100/V100
• E0 ~ 2 1052 erg R1003 V100
2 n
Wind/jet fed bubble (mech. luminosity LW )
• R ~ 26.2 pc (L36/n )1/5 t43/5
• V ~ 15.4 km/s (L36/n )1/5 t4-2/5
• t ~ 4 105 yrs R100/V100
• LW ~ 4 1039 erg/s R1002 V100
3 n
density n from I = 7.4x10-6 v22.4 n
erg/s/cm2
Energetics of ULX Bubbles: Energetics of ULX Bubbles: SNRSNR
Direct application of previous relations yields:
t ~ 106 yrs (robust); n ~ 0.3 – 10 cm-3 (from H intensity)
E0~1053 erg
~100 SNRs in 106 yrs (excluded !),
or hypernova ( that created ULX) ?
Supernovae – Hypernovae
Nomotoet al. 2003
Energetics of ULX Bubbles Energetics of ULX Bubbles winds/jetswinds/jets
Direct application of previous relations yields:
t ~ 106 yrs (robust);
E0~1053 erg
~100 SNRs in 106 yrs (excluded !), or hypernova (->ULX?)
or wind/jet fed :
LW ~ few 1039 erg/s; Mdot<10-6Msol /yr;
vW,j ~few 0.1 c (mildly relativistic jet velocity);
but unlike SS433, jets are not directly observed !
Energetics of ULX BubblesEnergetics of ULX BubblesDirect application of previous relations yields:
t ~ 106 yrs (robust); E0~1053 erg
~100 SNRs in 106 yrs (excluded !), hypernova (->ULX?)
orLJ~few 1039 erg/s; Mdot<10-6Msol /yr;
i.e., we predict vJ ~ few 0.1 c, probably dark jets
However:• much smaller IS density (n~0.01 like in excavated wind-
driven superbubbles) would lessen E0. and LJ.
• vs(optical) not necessarily = vexp of blastwave (X-ray); remember that IS medium is cloudy, like in real SNR
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
Inactive ULX bubbles ?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
NGC 1313 X-2
H
NGC 1313 field
ULX Optical Counterparts.
c.f. talk by Fabien Grisé
Optical data have suggested O star optical counterparts MXRB;
holy grail:observe RV curveto derive massesand decide betweenstellar BHB vs. IMBHs models
Holmberg IX X-1 counterpartHolmberg IX X-1 counterpart
HeII 4686
Brightest object in cluster hasstellar HeII 4686 emission
NGC 1313 X-2NGC 1313 X-2
clustercluster
Pakull et al. 2005: it is the blue component C1 of double C(Zampieri 2004,06 07)
HeII 4686
StellarStellar 4686 emission from 4686 emission from ULXULXUpper: 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
HeII 4686
Hol IX
NGC 1313 X-2
nebular
nebular
ULX optical counterparts: LMXB ULX optical counterparts: LMXB – like accretion disks– like accretion disks
ULXs 1313X-2, HoIX
Van Paradijs & McClintock 1994:
X-ray heated disks: Lv ~ Lx
1/2 a ~ Lx
1/2 Porb2/3 M1/3
~ HeII 4686 luminosity ~ LX
high intrinsic Lx, no beaming at work here
RV variation in NGC1313 X-2 RV variation in NGC1313 X-2 (?)(?)
HeII 4686: RV = 300 km/s in 20 dif confirmed Mx < 50 M (i.e., not IMBH !)
dotted line correspondsto RV of HI gas near XRS
What have we learnt ? What have we learnt ? fanciesfancies
• 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
What have we learnt ? What have we learnt ? factsfacts 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 ESNR)
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 !)
FIN
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