Download ULX nebulae

Nebulae Associated with
Ultraluminous X-ray Sources
P. Abolmasov,
Special Astrophysical Observatory
Very commonly used ionization diagram
Collisionally excited
(shocks or X-rays):
[NII]6583,6448
[SII]6717,6731
[OI]6300,6364
“High excitation”
(ionization potential
> 1Ry):
[OIII], HeII
[FeIII], ArIV etc…
Ultraluminous X-ray Sources (ULXs)
LX ≥ 1039 erg/s non-nuclear compact sources
Eddington limit
for ~ 10 M
Not young SNRs!
(usual a for stellar-mass BH)
Not AGNe!
Unknown nature!
(can be ~1040 erg/s bright)
Most popular models:
-IMBH with a massive donor star accreting @ 0.01-1 critical
(Eddington) rate
-Supercritical accretor like SS433 with a thick disk with a
funnel, seen face-on
Observational Properties:
-Luminosities 1039-1041 erg/s in the standard X-ray range
(Chandra 0.5-8keV)
-Powerlaw or powerlaw+soft excess (T ~ 0.1-0.2keV) X-ray spectra
-~1 per 20 giant spirals
-Connected to the young stellar population (5-20 Myr…)
-Some have radio counterparts (NGC5408 X-1, HoII X-1)
-Some have point-like optical counterparts identified with OB
supergiants
-Some are close to massive star clusters (usually offset by tens of parsecs)
-Many have nebular counterparts (ULX nebulae)
ULX nebulae:
-Shock excitation ([SII], [NII], [OI] etc. )
-Large sizes, ~50-500pc
-HeII λ4686 emission (stellar?)
What are they?
-SNRs? (too powerful)
-Superbubbles? (lack of young stars)
-X-ray ionized nebulae? (requires too much
X-rays in some cases!)
MH9/10, the optical
counterpart of HoIX X-1
(Grisé et al., 2006)
HoII X-1
Ho IX X-1
NGC6946 ULX1 (=X8, X11)
IC 342 X-1
“Peculiar SNRs”
Our results from the 6m:
Eight ULX nebulae
Two spectrographs :
-- MPFS (panoramic)
-- SCORPIO (long slit)
Medium spectral resolution (Δ ~ 5-10Å)
Spectral range 4000-7200Å
MF16
(counterpart of NGC6946 ULX-1):
34pc (~1,˝5)
X-ray source
coordinates:
20h 35m 00s.75
+60˚ 11' 30".9
(HST ACS,
filter F658N)
20pc (~1˝)
But: HeIIλ4686 / Hβ ~ 0.2 !!
Radio isophotes
(VLA)
LX ≈ 2.5 1039 erg/s (0.5-8.0 keV)
L(H) ≈ 2 1038 erg/s
L(optical lines, total) ≈ 2 1039 erg/s
Also a bright radio source
from Blair&Fesen, 1994
NGC 6946 galaxy:
D = 5,5 (from 5,1 to 5,9) Mpc
Scd, active star formation
MF16
Observations with the 6m SAO telescope
Spectrograph
wavelength range,Å
spectral
resolution
seeing,
arcsec
MPFS (panoramic)
4000-7000
~1000
1,5
SCORPIO (long-slit) 4000-5700
~2000
1,5
Long
Slit
MPFS
FOV
1˝
Emission lines’ mapping:
Hα
[OIII]
(5007+4959)
1˝
Barycenter shift:
line
H
:
H
:
HeII :
[OIII] :
[SII] :
[NII] :


-0,111 -0,088
-0,11 -0,10
0,72 -0,02
0,058 0,011
-0,116 -0,081
-0,061 -0,064
1˝
±0,013
±0,02
±0,02
±0,015
±0,014
±0,013
Hβ
[SII]
(6717+6731)
HeII4686
[NII]
(6548+6583)
Integral spectrum:
Very rich high-excitation spectrum
(HeII, FeIII, OIII) and bright shockionized lines (SII, NII, OI).
SCOPRIO spectrum:
 MPFS total
spectrum
Possible interpretations – fast (photoionizing)
shock waves or photoionization by a broadband
continuum…
Two-component lines:
HeII4686
H
[OIII]4959
[OIII]5007
V2-V1  120-130 km/s
[OIII]5007
Broader component width ~ 200-300km/s
H
For a single H line:
precursor
Shock
(cooling matter)
VS
(from Dopita&Sutherland, 1996)
Total luminosity in H (if the shock surface area is given);
Shock velocity estimate from the component ratio:
 FH  , precursor
VS  866 km  
s  F
 H  , shock



7.69
L(Hβ) = (7,2±0,4) 1037 erg/s
Single Hβ line
Narrow-to-broad components ratio 1,85±0,19
kinematics
Additional source of
excitation/ionization?
nH, cm-3
SHOCK WAVES OR
PHOTOIONIZATION?
from Evans et al., 1999

Only lgU~-5 can be provided by the extrapolated
model for X-ray spectrum (Chandra data, taken from
Roberts&Colbert, 2003), lgU~-2.7 needed
MF16
MF16
B/n1/2 =
Photoionization by power law continuum
(labelled by ionization parameter logarithm lgU)

F
1
U
d
cn 13.6eV h
Using single recombination line
Total effective recombination
coefficient for He++ for Case B
Weakly varying
function of physical
conditions
Recombination with HeII4686
emission coefficient
L<228Å ≥ 1039erg/s
HeII4686
L(HeII)=1.6 1037 erg/s
Cannot be explained by a
shock wave, and an EUV
source needed with
L<228Å ≥ 1039erg/s
MF16
Or X-ray source
with L ~ 1041 erg/s
or larger!
Photoionization by power
law continuum (labelled by
ionization parameter
logarithm lgU)
Pure photoionization models (CLOUDY 96.01 modeling
results):
Central source emitting:
fixed X-ray spectrum (best-fit from
Roberts&Colbert, 2003), with dilution
corresponding to 13pc
+
black body with temperatures
(3-30) 104K and integral flux
densities 0.3-7.0 erg/cm2/s
Photoionization best-fit:
lgT(K) = 5.15±0.05
(T~120 000K)
F = 0.6 ± 0.1 erg/cm2/s
=> UV luminosity ~1040erg/s
Other high-excitation nebulae:
M101 P098
from the work of Kuntz et al (2001)
High-excitation nebulae:
HoII X-1
Bubble nebulae: HoIX X-1
Bubble nebulae: IC342 X-1
HeII4686 accompanied by other high-excitation lines, both
allowed and forbidden (MF16)
Both high-excitation and low-excitation lines are enhanced
everywhere!
Seyfert
NLRs
PNe
Compare with
Baldwin’s
picture!
Photoionized HII
regions
ULXNe
SNRs
Unification scheme for ULNXe?
Low EUV luminosity / large shell size
High EUV luminosity / small shell
(the case of HoIX X-1 and IC342 X-1):
(the case of MF16):
Shock-ionized
shell
X-ray source
Very large
diffuse shell or
no shell at all
Strömgren zone
(M101 P098)
In the framework of supercritical accretor
model:
Supercritical wind photosphere emitting EUV quanta!
Higher massloss rate:
Wind photosphere
Lower mass loss:
Thin wind-blown bubble
HST images
B
W50 (VLA)
H+[NII] 
Optical emission of W50:
Optical filaments
Zealey et al.,1980
50pc
[OIII]5007 / H ~ 8 ?!!
L(H) ~ 1039 erg/s ?!!
Conclusions:
-All the observed ULX nebulae are at least partially shock-powered
-Practically all of them contain signatures of high excitation (bright
HeII, [OIII] lines)
-To explain the spectra of some of them, EUV source is needed even
brighter than the X-ray source
- Many of ULXs most likely have wind/jet activity similar to that of
SS433