European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain Andy Pollock XMM-Newton SOC...
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Transcript of European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain Andy Pollock XMM-Newton SOC...
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Physics and Dynamics of X-ray Plasma in Hot Stars
A.M.T. PollockRGS Calibration Scientist
European Space Agency, XMM-Newton Science Operations Centre,European Space Astronomy Centre, 28080 Madrid, España
Cassinelli, Cohen, Corcoran, Feldmeier, Gagné, Ignace, Henley, Leutenegger, MacFarlane,
Miller, Oskinova, Owocki, Raassen, Schulz, Skinner, Walborn, Waldron.
X-ray Grating Spectroscopy, Cambridge MA, 2007 July 11-13
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The X-ray spectrum of Puppis O4I
• lines resolved• no flat tops• He-like(fi(UV))• weak continuum
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The line-driven winds of hot stars
€
˙ M = 4πr2ρ(r)v(r)
v(r) = v∞(1− R* /r)β
LX/Lbol~10-7
X-rays from instabilities in the acceleration zone à la Lucy &
White (1980) et seq.
¿ X() ?¿ wind clumping ?
¿ mass-loss rates ?
Vela X-1 test
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The physics involved
• Shocks (cf SNRs)• collisionless• plasma driven• post-shock relaxation
• Plasma physics• Equilibrium - yes or no ?• T f(v)dv
• Gas dynamics• X-ray absorption in clumpy media• Chemical abundances• Magnetic fields• Consequences for current models
• line-driven instability shocks in single stars• numerical hydrodynamic simulations of colliding-wind binaries (CWBs)
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The high-resolution X-ray sample
• instrinsic X-rays• O2-O9-B0 I-V• WN2-8• WC4-WC9• LBV
• magnetic stars• colliding-wind binaries• ISM
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
X-ray spectra of O stars
Ori
LineProfile(!) Cohen+ (2006) moments Oskinova+ (2006) clumps Pollock (2007) TriLines Waldron & Cassinelli (2007)
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Stacked X-ray line profiles of single O stars
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Chandra MEG stacked profiles of more OB stars
Pup -2068 -829 +1937
Per-2180 -408 +2488
Ori -1585 -303 +1723
Ori -1495 -251 +1480
Ori -1613 -78 +1675
Ori -552 -94 +517
Oph -1055 -27 +787
Ori -2113 -44 +2262
blueV centralV redV
TriLine velocities (km/s)
the single TriLine profile is OK for all the lines in these OB stars disagreement with Miller+ (2002) for Ori disagreement with Waldron & Cassinelli (2007) for centralV
X-rays best for measurements of v∞
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The problem with the X-ray lines of O stars
Too symmetric (cf Owocki & Cohen 2001) Ingredients for a solution
X-ray opacity Reduction by UV, EUV & X-rays (Waldron 1984 et seq) Porosity (Owocki & Cohen 2006) Vela X-1 test ?
Location, location, location X(v(r)) = fX (v(r>R0)) (red half from behind the star)
CIE He-like triplets (Cassinelli+ 2001 Leutenegger+ 2006)
Waldron+ (1998) Cassinelli+ (2001) Townsend via Owocki & Cohen (2006)
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Some of the contenders
Oskinova+ (2006) CIE He-like locations POWR opacities highly clumped cool wind
1 clump per flow time
Cohen & Leutenegger (2007) empirical X-ray opacity X-ray starting radius wind porosity parameter
Pollock 2007, A&A, 463, 1111 abandon all this
Pup
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
A new paradigm for single O stars
All X-ray lines have the same velocity profile terminal velocity regime widths are from random not bulk velocities
Plasma is not in equilibrium reconsider CIE He-like radii
Plasma is collisionless (cf SNR shocks) relaxation times are long and energy exchange is slow no prompt hot electrons and no continuum ionization and excitation by means other than electron impact
charge exchange proton excitation ? v∞ vBohr !
rates ? B important
Are shocks required at all ? Many outstanding questions
origin of FeXVII 16.778 and exchange-term lines Why no RRCs ?
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
High-velocity microphysics of charged particles
inelastic collisionselastic collisions
ion >< ion
electron >< ion
excitation
ionizationcharge exchange
Coulomb collisions
€
ii ≈ 7 ×10−21cm2
σ ei ≈ σ ii me /mi
no neutral gas in hot-star winds
ii excitation ionization charge exchange 10-17 – 10-15 cm2
Spitzer (1956)
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
WR11 WC8+O at two binary phases
Willis, Schild & Stevens, A&A, 298, 549, 1995
CVI
RRC CV
RRC
X()
X()
Schild+ (2004)
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
WR48 WC5-6+OV+OI and a bright SNR
WR48 & SNR1ES0102-7219
CVI
RRC OVIII
RRC OVII
RRC
WR48• PSPC constant over P=19d• No photoionizing continuum
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
X-rays from 1 Ori C (B=1.1kG, P=15.4d)
WC7
O4-5
Gagné+ 2005
Wind dynamics dominated by B Lines from OVII to FeXXV hotter and narrower than other O stars “magnetically-channeled wind shock” MHD simulations work well models of Sco (B=0.5kG, P=41d) coming soon
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
X-rays from WR140 (P=7.94yr, D=14.1AU, e=0.88)
WR140 RXTE 2-10 keV (1-6Å)
http://lheawww.gsfc.nasa.gov/users/corcoran/wr140/wr140_rxte_lightcurves/Images/pcu2_l1_time.jpg
WC7
O4-5
Pollock+ 2005
WR in front
© ©
¡ CWB gas is not an ideal fluid ! current hydrodynamic simulations are obsolete including mine
there is no contact discontinuity B is important here too
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
The best Wolf-Rayet binary X-ray spectrum
WR140 Chandra HETG just before the 2001 periastron
vpshock models fit well¿ …but what does it mean ?
X-rays best for abundances
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Details of WR140’s HETG X-ray lines
• near periastron• near apastron
¡ this plasma is not in equilibrium !
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
X-rays from Carinae (P=5.5yr, e~0.9)
Henley+ (2007)
• Equilibrium ionization ?• He-like f/i ratio > low-density upper limit• same as WR140
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Statistical asides
Poisson statistics always apply P(n|) = e-n/n!
0 is a perfectly good measurement P(0|) = e-
log(likelihood) like XSPEC’s C-statistic is always valid C-statistic goodness-of-fit needs work for lots of ~ 0 Never rebin even low-resolution spectra
Who rebins beautiful 0.5” resolution Chandra spatial images ? Plot in linear coordinates
European Space Astronomy Centre Villafranca del Castillo, Madrid, Spain
Andy PollockXMM-Newton SOC
High-Resolution X-rays from Hot Stars
Are magnetic fields the key to hot-star X-rays ? 1 Ori C when B is dynamically in charge Ori when it’s not Distant binaries like WR140 and WR25 generate their own B
Observational work required 1 O star for 1 HETG Ms to emulate Capella
cf Leutenegger+ (2007) NVI and OVII resonance scattering in Pup continuum level distinguish alternative models
2009 January periastron passages of WR140 and Carinae close binaries in general
CHM rather than CWB
Theoretical work required proton ionization rates charge exchange NEI models