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