Charge-Exchange Mechanism of X-ray Emission V. Kharchenko ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge 1. Introduction - interaction between the solar/stellar wind and neutral gas - X-rays induced in the charge-exchange (CX) collisions - CX mechanism of X-ray emission from the Jupiter atmosphere 2. X-ray spectra induced by CX collisions - selective population of excited states of highly charged ions - X-ray and EUV radiative cascading spectra - diagnostic of ion compositions and velocities 3. Conclusions. Acknowledgments to my coauthors: Alex Dalgarno Ron Pepino Rosine Lallement Matt Rigazio

X-ray Image of Comet C/Linear 1999 X-ray Image of Comet C/Linear 1999 Lisse et al., Science (2001) Lisse et al., Science (2001) Sun visual light X-rays

X-ray Image of Comet McNaught-Hartley Krasnopolsky et al. (2002) observed with the Chandra X-ray telescope

EUV X-ray Krasnopolsky et al. (2001)Lisse et al. (2001) hνhν ROSAT data Photon Energy [keV] OVII (2 3 S S) 561eV

Interaction between the Solar Wind and Neutral Gases in the Heliosphere PlanetaryAtmospheres CometaryAtmospheres Interstellar gas Z q+ + A Z *(q-1) + A + X-ray Photons Cravens (1997 ) fast solar wind slow wind H2OH2O H H He O Z q+ = O 7+, C 6+, N 7+, Fe 13+, Mg 10+ …

X-ray emission from the polar regions of the Jupiter atmosphere Precipitation of energetic ions O q+ and S q+ into the Jupiter atmosphere. Ion energies: < MeV/amu Highly charged ions are produced by stripping collisions between precipitating magnetospheric ions and atmospheric atoms (molecules): I : O q+ + H  O (q+1)+ + e + H II : O (q+1)+ + H  O (q+2)+ + e + H ……………………….. N: O (q+n)+ + H  O* (q+n-1)+ + H + Magnetospheric ions Magnetic field O q+ S q+ h

Charge-Transfer Collisions nucleus Dust particles hνhν H O q+ hνhν A q+ + B A *(q-1)+ + B + electron Photon energy h Volume Emission Rate: W = n g n ions v i σ P photon yieldcollision rate minor SW ions: Number of photons (hν) O H H2OH2O O q+, C q+,Fe q+... H + and He 2+

Emission Spectra of Oxygen Ions O (q+1)+ + H  O* q+ + H+

X-rays induced by O *7+ ions in collisions of O *8+ with He atoms 2p - 1s

EUV CASCADING PHOTONS Å Å EXPERIMENT THEORY C 5+ + H 2 C *4+ + H 2 + C* 4+ WAVELENGTH Suraud et al.,1991

H2OH2O POPULATION OF ION EXCITED STATES IN ELECTRON-CAPTURE COLLISIONS Neutral atoms and molecules CO, O, He, H n-2 n-1 n ion core X-ray photon hνhν Multiplet Structure of Electronic States Singlet states S=0 Triplet states S=1 s p d f GROUND STATE Helium-like ions: C 4+, N 5+, O 6+ 23P23P 2 3 S metastable state n electron t = 0.001s L= 400m

O *6+ emission spectra detected in ion beam experiments [Greenwood et al. (2001)] Theoretical spectra: photon cascading [Kharchenko et al.(2003) ] {n,L} state-selective populations from the recoil-momentum spectroscopy measurements [Hasan et al. (2001)]

Solar Wind Electrons and Ions Minor Ions O q+ : O 5+ O 6+ O 7+ O 8+ C q+ : C 4+ C 5+ C 6+ Ne q+ : Ne 7+ Ne 8+ N q+ : N 6+ N 7+ and Fe q+ Si q+ Mg q+ …. (q = ) Ion velocity: ~ 300 – 1000 km/s slow fast solar wind Major Ions H + and He 2+

Total EUV and X-ray Emission Spectra Total Spectra =  i (Spectra of Individual SW Ions)

P(h  P(h ) – number of photons per SW ion [eV -1 ]

Ne* 8+

Sensitivity of EUV and X-ray spectra to the ion velocity V : collisions : C 6+ + H R1R1 R2R2 R 1 : R 2 = Function[ v ] EUV X-ray

Spectra of CX Emission Induced by the Slow Solar Wind from H and He gas

Emission from the Interstellar Hydrogen Gas (Heliospheric Ecliptic Plane) Pepino, Kharchenko, Dalgarno, Lallement (2004) H

Brightness Distribution in the Heliospheric Ecliptic Plane H and He H He

CONCLUSIONS The CX mechanism successfully describes the observed spectra and intensities of the EUV and X-ray cometary emission. The CX collisions of the SW ions with the interstellar H and He gas are an important local source the diffuse X-ray background. Ion composition of the solar wind has been determined from the cometary X-ray emission spectra. Relative intensities of the cascading emission lines provide unique information on the composition and velocities of heavy ions in astrophysical plasmas.

X-ray Emission from the direction of the dark Moon B.Wargelin et al. (2004) Sun Moon Earth SW ion

Spectra of X-Ray emission from two Comets McNaught-Hartley Linear S4 Lisse et al. (2001) Krasnopolsky (2004) Chandra X-ray telescope

Theoretical Models for O 8+ + H Emission Spectra of O* 7+ Ions

Emission Spectra ( Ion Beam Experiments ) O *6+

X-ray emission spectra of Ne* 9+ Slow collisions Ne Ne

O 6+ Emisson Beiersdorfer et al., Science (2003) O 7+ + CO S -1 1 S 2 3,1 P- 1 1 S

Laboratory Simulations of Cometary X-ray Spectra Beirsdorfer et al. Science, 2003

Theoretical Models for O 8+ + H Emission Spectra of O* 7+ Ions

Velocity Dependent Spectra of Cascading Emission of O* 7+ Ions

Theoretical and Experimental Spectra Ne H 2 O -> Ne* 9+ + H 2 O +

SW Velocity Diagnostic form Emission Spectra of the Soft Cascading Photons

O 6+ Emisson Beiersdorfer et al., Science (2003) O 7+ + CO S -1 1 S 2 3,1 P- 1 1 S

Photon Emission Rate and Rate of Charge Transfer Collisions R Sun  Collisional Depth =1  = 3 SW Ions + HO, H, O … O 5+ + H 2 O, H, O … Example: O 5+ O 8+ O 5+ O 7+ O 6+,,, and O 5+, O 6+, O 7+, and O 8+  = 2 R Emission of ions Emission of O* 4+ ions

100eV 

Heliospheric Emission : SW Ion Spectra from H and He gas