AGILE -ray detection of

M. Corcoran on behalf of the AGILE Team IAU Symposium, August 2009 AGILE Satellite (IABG, Munich 16 June, 2006)

350 kg satellite Gamma-ray astrophysics missions (above 30 MeV)

SAS-2 NASA Nov. 1972 – July 1973 COS–B ESA Aug. 1975 – Apr. 1982 CGRO NASA Apr. 1991 – Jun. 2000 AGILE ASI April 23, 2007 FERMI NASA June 11, 2008 The AGILE Payload: the compact instrument for high- energy astrophysics

It combines for the first time a gamma-ray imager (30 MeV- 30 GeV) with a hard X-ray imager (18-60 keV) with large FOVs (1-2.5 sr) and optimal angular resolution FERMI/GLAST AGILE A quick comparison AGILE FERMI/LAT 2 Aeff (100 MeV) (cm ) ~400 ~ 2000-2500 2 Aeff (10 GeV) (cm ) 500 ~ 8000-10000 FOV (sr) 2.5 2.5 sky coverage 1/5 whole sky Energy resolution 50 % 10 % (~ 400 MeV) PSF (68 % cont. radius) 100 MeV 4o - 5o 3o - 4o 1 GeV < 1o < 1o a comparison: 1-day exposure

AGILE FERMI (GRID) (LAT) FOV (sr) 2.5 2.5 sky coverage 1/5 whole sky Source livetime fraction ~ 0.5 ~ 0.16

1-day exposure (30 degree ~ 2 107 ~ (1-2) 107 off-axis, 100 MeV) cm2 sec cm2 sec Attitude fixed variable AGILE gamma-ray emission above 100 MeV

Cygnus Region Carina Region

Galactic Center AGILE study of the Galactic plane • Galactic Center region • Cygnus region • Carina region • Crux region

AGILE accumulated a large exposure in the Carina Region, equivalent to ~ 5 months of effective livetime for an exposure of 109 cm2 sec and flux sensitivity of 10-7 ph. cm-2s-1 above 100 MeV. Several old and new gamma-ray sources are detected, some are time variable Detection of Eta Carinae (average flux of a few 10-7 ph. cm-2s-1 above 100 MeV. The CARINA REGION (MW observations)

IRAS far-IR multicolor image Hubble (from N. Smith 2009 Handb. Star Form. Regions II p.138)

UV rays & winds of numberless young hot stars produce a wealth of spectacular nebular structures

X-Ray images AGILE gamma-ray map on same scale CHANDRA XMM-Newton ASCA

Hamaguchi et al. 2007 ApJ 663, 522 AGILE integrated gamma-ray map above 100 MeV of the Carina Region

Eta Carinae AGILE integrated gamma-ray map above 100 MeV of the Carina Region IRAS far-IR emission from the Carina Region AGILE discovery of gamma-ray emission from a source coincident with Eta Carinae

(integrated intensity map above 100 MeV) AGILE study of the Eta Car region (Tavani et al., 2009)

AGILE’s good angular resolution above 100 MeV resolves satisfactorily the region near Eta Car. 3 gamma-ray sources within a few degrees squared. the Eta Carinae gamma-ray counterpart is well separated from the anomalous X-ray pulsar AXP 1E 1048.1 – 5937 and from the unidentfied INTEGRAL source IGR J10447-6027. Detection of Eta Carinae (pre-periastron) (average flux of F = 40 x 10-8 ph. cm-2s-1 above 100 MeV during the 2008 pointings). Detection of a (relatively soft) gamma-ray flare on October 12-13, 2008

AGILE –Carina Region at 400 MeV AGILE-GRID, Eta Carinae at 400 MeV Eta Carinae average gamma-ray properties

• 7.8-sigma detection above 100 MeV • (l,b) = (287.6, -0.7) ± 0.3 ± 0.1 • F = (37 ± 5) x 10-8 ph. cm-2 s-1 • L = 3.4 x 1034 erg/s (2.3 kpc dist) Gamma-ray emission from Eta Carinae

The source was positively detected during several individual observing runs showing a roughly constant gamma-ray flux over the whole observations period. The October 2008 maximum is due to a flare (see next slides) rather than to a flux increase before periastron as in X-rays. Transient gamma-ray emission from Eta Carinae (12-13 Oct., 2008)

10-11 Oct. 12-13 Oct.

14-15 Oct. 16-17 Oct. The 11-13th October, 2008 Eta Car gamma-ray flare

11-13 Ott 08

5.2 detection (l,b) = 288.0, -0.4 ± 0.6 F = (270 ± 65) x 10-8 ph/cm2/s L =3 x 1035 erg/s (2.3 kpc dist)

2 days integration maps - counterclockwise a relatively “soft” flare (100 MeV vs 400 MeV maps)

> 100 MeV > 400 MeV

The gamma-ray flare of Oct 11-13, 2008 is mainly due to photons of energy lower than 400 MeV. The keV to MeV Energy Spectrum of Eta Carinae

Oct 2008 Flare

SAX MECS

AGILE average emission

INTEGRAL Although data are not simultaneous, it is interesting to note that the average AGILE spectrum together with the INTEGRAL historical spectrum is in qualitative agreement with expectations based on inverse Compton and/or pion decay models of gamma-ray emission from colliding binaries (Raimer et al, 2006) Summary on the Eta Car region

Detection of Eta Carinae (pre-periastron) (average flux of F = 40 x 10-8 ph. cm-2s-1 above 100 MeV during the 2008 pointings). Detection of a gamma-ray flare from Eta Carinae (Oct. 12-13, 2008) (F = 270 x 10-8 ph. cm-2s-1 above 100 MeV). Very weak or absent emission near periastron (AGILE ToO observation, Jan. 9-17, 2009) Weak or absent emission detected above 100 MeV during an AGILE pointing in April 2009. Conclusions AGILE detected a point source centered on the object Eta Carinae

identification with the Eta Carinae is supported by:

• Eta Car is a very massive and powerful CW binary system • it is the strongest and hardest 2-10 and 22-100 KeV source in the field • the two nearby hard X-ray sources detected by INTEGRAL are outside the AGILE error box • it has a non-thermal X-ray excess (BSAX, INTEGRAL, ) • time variability both in X- and gamma-rays • no alternative identification so far

This is the first remarkable detection above 100 MeV of a colliding wind binary system, confirming the efficient particle acceleration and highly non-thermal nature of the strong shock in a CWB.