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