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

2. 70’s 80’s The past EPIC EPIC 2002 1988 Optical ID G” 1983
X-ray counterpart 1E
EPIC
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 The tails account for 2 10-6 Edot Edot 3 1034 erg/sec
D = 160 pc
m=170 mas/y
vtr =120 km/sec
Geminga luminosity erg/sec (0.1-5 keV)
Tails luminosity erg/sec
The tails account for Edot

6. VNS=mD/cos(i)

9. i < 30°

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

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

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

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

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

15. 1014 eV electrons will have a Larmor radius
of cm  thickness cm 27”
1014 eV electrons will loose half of their energy in 800 y .
180 “ / 170 mas/y = 1,000 y

16. Search for Ha emission

17. No Ha implies neutral H < 0.01

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