Charge-Exchange Mechanism of X-ray Emission V. Kharchenko ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge 1. Introduction - interaction between.

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 DalgarnoRon PepinoRosine LallementMatt Rigazio

X-ray ImageX-ray Image of Comet C/Linear 1999of Comet C/Linear 1999

Lisse et al. , Lisse et al. , Science (2001)Science (2001)

Sun

visual light

X-rays

X-ray Image of Comet McNaught-HartleyKrasnopolsky et al. (2002)

observed with the Chandra X-ray telescope

EUV X-ray

Krasnopolsky et al. (2001) Lisse et al. (2001)

hν

ROSAT data

Photon Energy [keV]

OVII (23S --11S) 561eV

Interaction between the Solar Wind and Neutral Gases in the Heliosphere

PlanetaryPlanetaryAtmospheresAtmospheres

Cometary Cometary AtmospheresAtmospheres

Interstellar gasInterstellar gas

Z q+ + A Z*(q-1) + A+

X-ray Photons

Cravens

(1997)

fast solar wind

slow wind

H2OH

H

He

O

Zq+ = O7+, C6+ , N7+ , Fe13+, Mg10+ …

X-ray emission from the polar regions of the Jupiter atmosphere

Precipitation of energetic ions Oq+ and Sq+

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 : Oq+ + 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

Oq+Sq+

h

Charge-Transfer Collisions

nucleus

Dust particles

hν H

Oq+

hν

Aq+ + B A*(q-1)+ + B+

electron

Photon energy h

Volume Emission Rate:W = ng nions vi σ P

photon yieldcollision rate

minor SW ions:

Number of photons

(hν)

O

H

H2O

Oq+, Cq+ , Feq+ ...

H+ and He2+

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

180 220 260

180 220 260

Å

Å

EXPERIMENT

THEORY

C5+ + H2 C*4+ + H2+

C*4+

WAVELENGTH

Suraud et al.,1991

H2O

POPULATION OF ION EXCITED STATESIN ELECTRON-CAPTURE COLLISIONS

Neutral atoms and moleculesCO, O, He, H

n-2

n-1nion core

X-ray photon

hν

Multiplet Structure of Electronic States

Singlet states S=0 Triplet states S=1

s p d f s p d f

GROUND STATE Helium-like ions: C4+ , N5+ , O6+

23P

23S metastable state

n

electron

4

2

3

1

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 WindElectrons and Ions

Minor IonsOq+: O5+ O6+ O7+ O8+

Cq+: C4+ C5+ C6+

Neq+: Ne7+ Ne8+

Nq+: N6+ N7+

andFeq+ Siq+ Mgq+ ….

(q = 6 - 16)

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 : C6+ + H

R1R2

R1 : R2 = 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)

SunMoon

Earth

SW ion

Spectra of X-Ray emission from two Comets

McNaught-Hartley

Linear S4Lisse 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 Ne10+ + Ne

O6+ Emisson Beiersdorfer et al., Science (2003)

O7+ + CO2

23S -11S

23,1P- 11S

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

NeNe10+10+ + H + H22O -> Ne*O -> Ne*9+9+ + H + H22OO++

SW Velocity Diagnostic form EmissionSpectra of the Soft Cascading Photons

O6+ Emisson Beiersdorfer et al., Science (2003)

O7+ + CO2

23S -11S

23,1P- 11S

Photon Emission Rate and Rate of Charge Transfer Collisions R

SunCollisional Depth =1Collisional Depth =1

= 3= 3

SW Ions

O 5+ + H + H2O, H, O …O, H, O …

Example: O5+

O8+

O5+

O7+

O6+

O5+, , O6+ ,, O7+ , and , and O8+

= 2= 2

R

Emission of Emission of O*4+ ions ions

100eV100eV

Heliospheric Emission :SW Ion Spectra from H and He gas