1. Characteristics of Swift’s intermediate population bursts
A. de Ugarte Postigo, I. Horvath , P. Veres , Z. Bagoly , L. G. Balazs , D. A. Kann , C. C. Thöne , P. D’Avanzo, M.A. Aloy , S. Campana , S. Foley , J. Mao , S. Covino, A. J. Castro-Tirado, J. P. U. Fynbo , J. Gorosabel , P. Jakobsson , L. Amati , and M. Nardini

2. Sample and classification
Classification by Horváth et al. (2010). Clustering analysis.
First 4 years of Swift.
Burst with redshift (136):
12 short
28 intermediate
82 long
Contamination is significant!

3. Redshift distribution
Median redshift:
0.46 for short
1.33 for intermediate
2.05 for long
K-S test:
Short-long: %
Short-interm.: 0.6%
Interm.-long: 7%

4. Afterglow luminosity: X-ray
K-S test at 100 sec:
Short-Interm.: 2.2%
Short-Long: 0.02%
Interm.-Long: 0.003%
K-S test at 104 sec:
Short-Interm.: 0.13%
Short-Long: 0.003%
Interm.-Long: 0.002%

5. Afterglow luminosity: Optical
K-S test at 100 sec:
Interm.-Long: 11%
K-S test at 104 sec:
Interm.-Long: 3.3%

6. Dark bursts Intermediate: 5 out of 32 are dark (16%).
Long: 27 out of 90 are dark (30%).
K-S test with only detections give 4.6% of coming from the same population.

7. Hydrogen column density
X-ray: Intermediate bursts similar to long:
K-S test gives 5.1%
Optical: Small amount of data to do statistics. There is no clear trend.

8. Optical extinction Same distribution as for long bursts.
K-S test gives 61% probability of coming from the same population.

9. Epeak vs. Eiso correlation
Valid for long GRBs but not for short
Mostly valid for intermediate bursts.
Slight trend to find them above the fit

10. Spectral lags
Short have negligible lags, while intermediate and long tend to positive lags.
K-S test:
Short-Long: 0.017%
Short-Interm.: 0.009%
Interm.-Long: 77%

11. Conclusions Intermediate GRBs are similar to long GRBs in:
Spectral lags
Epeak vs. Eiso correlation
Similar intrinsic extinction
But they differ in other aspects:
Afterglow luminosity (specially in X-rays)
Slightly lower redshifts
More long dark bursts
Differences with short bursts are more significant
Same progenitor as long bursts but with slightly different conditions

12. Thanks!!!