GRB 020127: Chandra observations

Kristian Pedersen and Jens Hjorth

Chandra ACIS-I images

First epoch (GRB trigger +3.56-3.68 days) Chandra ACIS-I 10 ksec image with HETE/IPN localization (blue lines) and X-ray afterglow candidate (source A14 (=B16), GCN #1249). Second epoch (GRB trigger +14.09-14.21 days) Chandra ACIS-I 10 ksec image with HETE/IPN localization (blue lines) and X-ray afterglow candidate (source A14 (=B16), GCN #1249). Cuts and colors similar to first epoch image.

Chandra ACIS-I spectra


Background subtracted spectra for first and second Chandra epoch (approx. 10 ksec each) with best fit intrinsic power law model with absorption at z=0, fixed at the Galactic value (0.0495e+22 cm^2). Best fit photon index = 1.7 +/-0.6, Chi sq = 4.9 for 8 d.o.f.


Background subtracted spectra for first and second Chandra epoch (approx. 10 ksec each) with best fit intrinsic power law model with absorption at z=0 left as a free parameter. Best fit parameters: Photon index = 2.3 +1.9/-1.2, N_H = 0.29 +1.36/-0.29, Chi sq = 4.3 for 7 d.o.f.


Background subtracted spectra for first and second Chandra epoch (approx. 10 ksec each) with best fit intrinsic power law model with absorption at z=0 fixed at the Galactic value and absorption at z=1 left as a free parameter. Best fit photon index = 2.4 +3.5/-1.2, N_H=1.3 +7.7/1.3, Chi sq = 4.3 for 7 d.o.f.


Confidence countours (1,2,3 sigma) in photon index, absorbing column density plane, assuming absorption in excess of Galactic absorption is at redshift z=1 (spectral fit shown immediately above).

Chandra ACIS-I lightcurves


Background subtracted lightcurve for first and second Chandra epoch (approx. 10 ksec each) with best fit power law decay model. Best fit photon index = -0.45 +/-0.46, Chi sq = 1.85 for 3 d.o.f.


Same as above, but only one time bin for each epoch and same power law decay model.


Version: May 30, 2003.