Transcript SUBARU and ESO/VLT Observations of ULX Counterparts and

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 Bubbles
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
SS433 & Cyg X-1
Mechanically inflated
bubbles due to
XRB jets (or SNR ?)
(radio-images)
Gallo et al 2005
6 pc
! note different scale !
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
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 Xray position (see later)
ULX NGC 1313 X-2
Previously candidate for
galactic neutron star !
location far away (9kpc)
from nucleus of N1313
no nearby starburst
diameter 400 pc
Laurent Mirioni’s thesis
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 photoionization
Strömgren spheres around O stars
Even hottest massive
stars (O2,3 V) do not
emit substantial He+
Ly cont (hn > 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
X-ray ionized nebula
Halpern
&
Grindlay
1980
no sharp Stroemgren
spheres;
‘warm’ He++ zone:
 HeII4686 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 II
Chandra position coincident with
He III region
structure confirmed by Kaaret et al 04
From Laurent Mirioni’s thesis; nebula is density-bound (optically thin)
beyond heel
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
HeII 4686 X-ray photon counting
X-ray photoionization
models (CLOUDY) show
good agreement with
Zanstra photon counting
for 4686 flux; i.e.
LHeII4686  LX
if the nebula indeed
no, or only little, X-ray
beaming
“sees” the total isotropic
X-ray luminosity,
i.e. LX ~ 1040 erg/s
Shock ionization
A few elements of shock physics
Adiabatic, non-radiative shock ( no B field)
n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 r0 vs2; T1 ~ 105 K v1002
Isothermal, fully radiative shock (no B field)
n2 = M2 n0; v2 = vs; P2 = r0 vs2 ;
T2=T0
Precursor
Dopita &
Sutherland 95:
vs = 400 km/s
A few elements of shock physics
Adiabatic, non-radiative shock ( no B field)
n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 r0 vs2; T1 ~ 105 K v1002
Isothermal, fully radiative shock (no B field)
n2 = M2 n0; v2 = vs; P2 = r0 vs2 ;
T2=T0
Precursor
[0I] 6300
Dopita &
Sutherland 95
vs = 400 km/s
A few elements of shock physics
Adiabatic, non-radiative shock ( no B field)
n1 = 4 n0; v1= 3/4 vs ; P1 = 3/4 r0 vs2; T1 ~ 105 K v1002
Isothermal, fully radiative shock (no B field)
n2 = M2 n0; v2 = vs; P2 = r0 vs2 ;
T2=T0
For fully radiative shocks a certain fraction of the
dissipated energy (‘shock luminosity’ [erg/cm2/s])
L = ½ r vs3
is radiated as H recombination radiation, i.e., L (~0.003 x L)
L = 7.4x10-6 v22.4 n0 erg/cm2/s
Shock diagnostics 1
10
5007/
3
1
.3
[OIII]5007/H
ratio as function
of schock vel. vs
(Dopita et al 1984)
Shock diagnostics 2: uncomplete shocks
Distance from shock
OIII5007/ H
100
Distance from shock
1.0
OIII5007
10
H
1
0.1
Raymond
at al. 1988
OI6300/H
0.0
high
[OIII]5007/ H
ratios (>6)
 uncomplete
shocks (not XIN !)
high
[OI]6300/ H
ratios (>0.1)
 complete
shocks
Holmberg IX X-1 Nebula
Subaru
Ha [OIII] B
30 "
=
500 pc
SE
shock ionized nebula;
breakout towards SE with incomplete shocks
ULX IC 342 X-1
Roberts et al, MNRAS (2003)
Subaru observations (Grisé et al)
INTEGRAL field spectrograph:
Cont5000 H [OIII]-contours
- ‘high-ionization’ cones are not confirmed
- 5007/ H varies as function of vs and of completeness !
- i.e., no indication of non-isotropic X-ray emission
Kinematics of ULX Nebulae
Holm IX
NGC1313 X-2
H
[NII] 6584
IC 342 X-1
Vexp = 80 – 150 km/s
Holm II
Pakull & Mirioni 2002
NGC1313-X2 nebula
•
•
•
•
E
courtesy D. Wang
see Ramsey et al 2006
W
Size ~ 570 x 400 pc
V ~ 100 km/s
n ~ 0.2 cm-3
E ~ 1.0 x 1053 erg
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 2007
IR diagnostic diagram:
regions around 5/6
ULX appear to have
higher ionization than
normal HII regions;
i.e. AGN-like
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 V1002 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 V1003 n
density n from I = 7.4x10-6 v22.4 n erg/s/cm2
Energetics of ULX Bubbles:
SNR
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
Nomoto
et al. 2003
Energetics of ULX Bubbles
winds/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 Bubbles
Direct application of previous relations yields:
t ~ 106 yrs (robust); E0~1053 erg
 ~100 SNRs in 106 yrs (excluded !), hypernova (->ULX?)
or
 LJ~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 winddriven 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 ?
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 W/4p > 1/10 !
NGC 1313 X-2
H
NGC 1313 field
H
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
Holmberg IX X-1 counterpart
HeII 4686
Brightest object in cluster has
stellar HeII 4686 emission
NGC 1313 X-2
cluster
Pakull et al. 2005: it is the blue
component C1 of double C
(Zampieri 2004,06 07)
HeII 4686
Stellar 4686 emission from ULX
Upper: SUBARU spectrum of
nebular
the 22.8 mag optical counterpart of Hol IX X-1. The stellar
4686 has EW = 9A
NGC 1313 X-2
Lower: ESO-VLT spectrum of
23.4 mag NGC 1313 X-2. Stellar
4686 EW = 10 A.
HeII 4686
Hol IX
HeII 4686
nebular
ULX counterparts resemble very
luminous (Mv ~ -5) LMXB, i.e. X-ray
heated accretion disks
(not SS433-like: there EWs several
100 A !!)
ULX optical counterparts: LMXB –
like accretion disks
ULXs 1313X-2, HoIX
Van Paradijs & McClintock 1994:
X-ray heated disks:
Lv ~ Lx1/2 a
~ Lx1/2 Porb2/3 M1/3
~ S
HeII 4686 luminosity ~ LX
 high intrinsic Lx, no
beaming at work here
RV variation in NGC1313 X-2 (?)
dotted line corresponds
to RV of HI gas near XRS
HeII 4686: RV = 300 km/s in 20 d
if confirmed  Mx < 50 M (i.e., not IMBH !)
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
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 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