nebulae associated with ultraluminous x-ray sources
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Nebulae Associated with Nebulae Associated with
Ultraluminous X-ray SourcesUltraluminous 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
(usual a for stellar-mass BH)Not AGNe!
Not young SNRs!
(can be ~1040 erg/s bright)
Unknown nature!
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:
MH9/10, the optical counterpart of HoIX X-1
(Grisé et al., 2006)
-Shock excitation ([SII], [NII], [OI] etc. )
-Large sizes, ~50-500pc
-HeII λ4686 emission (stellar?)
-SNRs? (too powerful)
-Superbubbles? (lack of young stars)
-X-ray ionized nebulae? (requires too much X-rays in some cases!)
What are they?
Ho IX X-1
HoII 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
34pc (~1,˝5)
20p
c (~
1˝)
LLX X ≈≈ 2.5 10 2.5 103939 erg/s erg/s (0.5-8.0 keV)(0.5-8.0 keV)
L(HL(H) ) ≈≈ 2 10 2 103838 erg/s erg/s
L(optical lines, total) L(optical lines, total) ≈≈ 2 10 2 103939 erg/s erg/s
Also a bright radio sourceAlso a bright radio source from Blair&Fesen, 1994
MF16 (counterpart of NGC6946 ULX-1):
But: HeIIλ4686 / Hβ ~ 0.2 !!
(HST ACS, filter F658N)
Radio isophotes
(VLA)
X-ray source coordinates:20h 35m 00s.75 +60˚ 11' 30".9
MF16
NGC 6946 galaxy:
D = 5,5 (from 5,1 to 5,9) Mpc
Scd, active star formation
Observations with the 6m SAO telescopeSpectrograph wavelength range,Å spectral seeing,
resolution arcsec
MPFS (panoramic) 4000-7000 ~1000 1,5
SCORPIO (long-slit) 4000-5700 ~2000 1,5
MPFS FOV
Long Slit
1˝
Hα
Hβ [SII](6717+6731)
[OIII](5007+4959)
HeII4686 [NII](6548+6583)
Emission lines’ mapping:
Barycenter shift:
line H : -0,111 -0,088 ±0,013 H : -0,11 -0,10 ±0,02 HeII : 0,72 -0,02 ±0,02 [OIII] : 0,058 0,011 ±0,015 [SII] : -0,116 -0,081 ±0,014 [NII] : -0,061 -0,064 ±0,013
1˝
1˝
Integral spectrum:
MPFS total spectrum
Very rich high-excitation spectrum (HeII, FeIII, OIII) and bright shock-ionized lines (SII, NII, OI).
SCOPRIO spectrum:
Possible interpretations – fast (photoionizing) shock waves or photoionization by a broadband continuum…
[OIII]5007
H
HeII4686H
[OIII]4959[OIII]5007
Two-component lines:
V2-V1 120-130 km/s
Broader component width ~ 200-300km/s
(from Dopita&Sutherland, 1996)
,
,
7.69
866 H precursorS
H shock
FkmV s F
Total luminosity in H (if the shock surface area is given);
Shock velocity estimate from the component ratio:
For a single H line:
VS
precursorShock(cooling matter)
L(Hβ) = (7,2±0,4) 1037 erg/s
Narrow-to-broad components ratio 1,85±0,19kinematics
Additional source of excitation/ionization?
Single Hβ line
nH, cm-3
SHOCK WAVES OR PHOTOIONIZATION?
MF16
MF16
from Evans et al., 1999
Photoionization by power law continuum (labelled by ionization parameter logarithm lgU)
13.6
1
eV
FU d
cn h
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
B/n1/2 =
Using single recombination line
Total effective recombination coefficient for He++ for Case B
Recombination with HeII4686 emission coefficient
Weakly varying function of physical
conditions
L<228Å ≥ 1039erg/s
L(HeII)=1.6 1037 erg/sHeII4686
Cannot be explained by a shock wave, and an EUV source needed with
L<228Å ≥ 1039erg/s
MF16
Photoionization by power law continuum (labelled by ionization parameter logarithm lgU)
Or X-ray source with L ~ 1041 erg/s or larger!
Pure photoionization models (CLOUDY 96.01 modeling results):
Photoionization best-fit:
lgT(K) = 5.15±0.05
(T~120 000K)
F = 0.6 ± 0.1 erg/cm2/s
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
=> UV luminosity ~1040erg/s
Central source emitting:
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
HeII4686 accompanied by other high-excitation lines, both allowed and forbidden (MF16)
Both high-excitation and low-excitation lines are enhanced everywhere!
Compare with Baldwin’s picture!
SNRsULXNe
PNe
Seyfert NLRs
Photoionized HII regions
Unification scheme for ULNXe?
Low EUV luminosity / large shell size
(the case of HoIX X-1 and IC342 X-1):
High EUV luminosity / small shell
(the case of MF16):
Shock-ionized shell
X-ray source
Strömgren zone
Very large diffuse shell or no shell at all
(M101 P098)
In the framework of supercritical accretor model:
Supercritical wind photosphere emitting EUV quanta!
Wind photosphere
Thin wind-blown bubble
Lower mass loss:
Higher mass-loss rate:
HST images
B
H+[NII]
W50 (VLA)
Optical filamentsOptical emission of W50:
[OIII]5007 / H ~ 8 ?!!L(H) ~ 1039 erg/s ?!!
50pc
Zealey et al.,1980
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
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