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The XMM observation of Geminga

The XMM observation of Geminga. 100 ksec of GT time. Geminga strikes again. 70’s. 80’s. The past. 1988 Optical ID G”. EPIC. 1983 X-ray counterpart 1E0630+178. EPIC 2002. >1992 ROSAT 237 msec pulsation EGRET and COS B. >1993 Proper motion of G”. >1996 parallax of G”.

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The XMM observation of Geminga

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  1. The XMM observation of Geminga 100 ksec of GT time Geminga strikes again

  2. 70’s 80’s The past 1988 Optical ID G” EPIC 1983 X-ray counterpart 1E0630+178 EPIC 2002

  3. >1992 ROSAT 237 msec pulsation • EGRET and COS B >1993 Proper motion of G” >1996 parallax of G” >1998 feature in optical >1998 absolute position of G” >1998 Gamma timing with proper motion

  4. 77 x 2 ksec

  5. Energetics Edot 3 1034 erg/sec D = 160 pc m=170 mas/y vtr =120 km/sec Geminga luminosity 3 1031 erg/sec (0.1-5 keV) Tails luminosity 6.8 1028 erg/sec The tails account for 2 10-6 Edot

  6. VNS=mD/cos(i)

  7. i < 30°

  8. RSO < 40” Geometrical model with i < 30° yields 20” < RSO < 30”

  9. from bow-shock VNS=mD/cos(i) we can obtain 0.06 < rISM < 0.15 at/cm-3 which implies 7 < M < 20

  10. What produces the X-rays Power law spectrum -> synchrotron radiation -> need for electrons and magnetic field

  11. From bow-shock theory rshock = 4 rISM Since B is frozen-in Bshock = 4 BISM Bshock = 10-5 G

  12. To produce keV photons in 10-5 G B field one needs 1014 eV electrons

  13. 1014 eV electrons will have a Larmor radius of 3.4 1016 cm  thickness 6.8 1016 cm 27” 1014 eV electrons will loose half of their energy in 800 y . 180 “ / 170 mas/y = 1,000 y

  14. Search for Ha emission

  15. No Ha implies neutral H < 0.01

  16. Conclusions Geminga accelerates electrons up to E 1014 eV 0.06 < rISM < 0.15 at/cm-3 BISM < 2-3 10-6 Gauss The ISM is fully ionized by Geminga

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