Cygni before GLAST

1
?-Cygni before GLAST

• Alberto Carramiñana
• Instituto Nacional de Astrofísica, Óptica y
  Electrónica
• Tonantzintla, México
• The Multimessenger approach to HE ?-ray sources
• Barcelona, 4- 7 july 2006

2
The ?-source 2CG 0782

• One of 25 Cos-B sources
• Located in the Cygnus region
• Also 2EG J20204026, GeV J20204023, 3EG
  J20204017
• F(gt100 MeV) 1.23?10-6 cm-2s-1 ? EF2?10-10erg
  cm-2s-1 the brightest
  unidentified EGRET source
• steady source, hard spectrum ?2.08
• break at 4 GeV (photons up to 16 and 18 GeV)

3
Identifiyng 2EG J20204026

• Located at
• 202034 402624 -- 8 radius (95 CL)
• GeV photons 202015 402100 -- 20?14 box (95
  CL)
• Inside SNR ?-Cygni (G78.22.1 _at_ 1.5 kpc)
• No pulsations detectable in EGRET data
• Unresolved with Rlt0.5?
• Multiwavelength ID approach, Geminga-like

Brazier et al. MNRAS 281, 1033 (1996)
4
Identifying 2EG J20204026

• ROSAT PSPC data on ?-Cygni SNR
• One X-ray point source RX
  J2020.24026
• Fx 4?10-14 erg cm-2s-1? F?/Fx ? 5000
• no radio F400lt600 mJy
• A 15-mag star in 5 error box (type K0V) - ruled
  out as RX J2020.24026 and 2EG J20204026

Brazier et al. (1996)
5
A deeper look
Becker et al. ApJ 615, 897 (2004)

• Now to 3EG J20204017
• at 202101 401748 (displaced .10,-.14º)
• RX J2020.24026 outside 95 (in 99)
• Chandra observations of RX 2020.24026
• coincident with K star
• Fit to ROSAT-HRI points to dlt356 pc distance
• Partial coverage of 3EG error box
• 38 cxo sources!

RX J2020.24026
GBT on entire 99 3EG box S820lt40?Jy,
S1400lt20?Jy radio quiet box
6
3EG J20204017 (II)
Weisskopf et al. astro-ph/0606596

• Chandra observation of 3EG box
• 30 point sources
• Sx 10-13 to 10-14 erg cm-2 s-1

7
S(0.5-8 keV) 10-15 erg cm-2s-1
1-30
? S?/Sx gt 2000 - 20000
8
?
?
?
? ?
? ?
? ?
? ? ?
Too many candidates left!!
9
The ?-source 2CG 0782

• Uncertainty in error box location
• 2EG (305.14, 40.44) 0.15º
• GeV (305.07, 40.35) (0.30,0.25) º
• 3EG (305.25, 40.29) 0.15º
• Coincidence with SNR call for PSR-ID
• S?/Sx gt 2000 - 20000
• Optical?
• Radio below 40 ?Jy definitively radio quiet!

It will get it!