1. TOWARDS THE FIRST FERMI SNR CATALOG F. Giordano 1, T. Brandt 2 & F. Acero 2, F. de Palma 1, J. Hewitt 2 for the Fermi Collaboration 1 University and INFN Bari 2 NASA Goddard Space Flight Center

2. F. Giordano 2 Of the 78 SNRs with GeV associations detected in the 2-year Fermi-LAT catalog (2FGL) roughly 45% are expected to be chance coincidences. Why a dedicated pipeline? - Characterize GeV emission in regions containing known SNRs - Evaluate systematics, including diffuse models and variability - Examine multiwavelength correlation, including spectrum and morphology for radio, X-ray, and TeV and CO, maser, IR, … - Determine statistically significant SNR classification(s) and perform spectral modeling With this project we intend to:

3. Where we started from… We survey 278 known Galatic SNRs, identified mainly in radio compiled in Green’s (2009) SNR Catalog

4. Some preliminary numbers SNR catalog results: 52 of 278 Radio SNRs Detected Sources 12 previously identified SNRs 7 are identified as NOT SNRs (PSR, PWN, HMB or AGN) 6 New significantly Extended SNR Candidates 27 Pointlike Candidates 14 more SNR-like 17 more PSR-like

5. We have run our extended search tool We have a powerful and reliable tool to search for spatially extended source and determine the significance of the extension (Lande+ 2012) This pipeline resulted in 6 new significantly extended new SNR candidate Fermi LAT best PSF GeV Extension

6. And Collected MW data Green Circle: radio SNR Cyan Circle: Fermi error circle MW data are being used to confirm or discard the associations/identification W49B Case

7. And studied Systematics from the Diffuse -A grid of 8 models, varying the CR source distribution (SNR and Lorimer), the halo size (4 kpc and 10 kpc), and the HI spin temperature (150K and optically thin) -free independent normalization coefficients for the inverse Compton component and for the components associated to HI and CO divided in 4 Galactocentric annuli More plots: poster by T.J.Brandt+ PuppisA Case 123 4 L=30° L=60° L=-60° L=-30°

8. 8 Preliminary results I SNRs Radio vs GeV Flux Remnants known to be interacting with large molecular clouds show a good correlation Young seems to be more out-liers PSRs contamination is under investigation (MW data) New Candidates

9. 9 Diameter traces SNR evolution (in Sedov stage R  t 2/5 ) Interacting SNRs generally show higher L(GeV) than young SNRs Preliminary results II Effect of Environment?

10. 10 Preliminary results III Effect of Age?  We also observe softening of the GeV index with increasing age  due to changing emission mechanism?  due to different environments? Young SNRs have generally harder GeV indices, but no clear trends for interacting SNRs

11. 11 Concluding… Procedure: We have set-up a dedicated procedure to characterize GeV Emission (MW data, extension, diffuse systematics…) Numbers: We now have 52 detected: 12 previously identified SNRs, 6 new extended, 27 point-like Classes: Interacting SNRs Soft index (possible indication of a break @ GeV) Higher density clouds act as target for high L GeV Young SNRs Seem to have Harder index No GeV spectral break Lower density ISM/CSM “Collective” behavior Radio-gamma correlation apparent, but not universal (SNR upper limits are interesting constraint) Luminosity and Index show correlation with age/environment For more details see poster by T.J.Brandt’s

12. 12 Preliminary results IV Radio vs GeV Index PRELIMINARY Young SNRs (i.e. RX J1713, VelaJr) show harder GeV index than inferred from radio ( Γ = 2  +1 ), possibly suggesting an IC origin Many SNRs show soft GeV index suggesting a ~ GeV break.

13. Some results: PuppisA see M.Lemoine-Goumard talk Hewitt+ 2012