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Catalogue XRT results for GRB 110731A

Data were analysed using HEASOFT version 6.29

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Summary Information

RA:18h 42m 01.06sLC breaks:2
Dec:-28° 32′ 13.4′′LC type:Oddball.
Err:1.4′′NH,intr.:3.13×1021 cm-2
Gal long:6.224Redshift2.83
Gal lat:-10.703Γ1.8
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Jump to: Light curve | Spectra | Compare to other bursts.

If you use any of these data, please cite Evans et al. (2009), which describes how these products were created (see the usage policy for more information).

Light curve

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This light curve comes from the light curve repository (if you use it, please cite Evans et al [2007, 2009]. Flares, marked by cross-hatched regions, are identified automatically, but may have been manually corrected. These are excluded from the fit. Any power-law breaks added to the fit must be required at the 4-σ level (according to an f-test) to be included in the best-fit. Details of all fits attempted are given below the plot. For more information see the light curve fitting documentation.

Fitted light curve of GRB 110731A

Fit Details

Nbreaksχ2dofCommentsImage
0356279Image of this fit
1299277Break required.

(3.16e-09 % probability of chance improvement)
Image of this fit
2277275Break required.

(2.91e-03 % probability of chance improvement).
This is the best fit.
Image of this fit
3262273Break significance <4-σ
(0.04 % probability of chance improvement)
Image of this fit
4258271Break significance <4-σ
(0.06 % probability of chance improvement)
Image of this fit

There are 1 flares excluded from the fit:

  • 61.9—90.0 s

The best-fitting light curve has 2 breaks.

Click on the number of breaks in the table to the right to change which fit is plotted above and detailed below.

Currently showing the best fit.

α1-1.50 (+0.00, +1.20)
Tb,165 (+6, -2) s
α21.126 (+0.020, -0.025)
Tb,27129 (+6.80 × 103, -4025) s
α31.30 (+0.07, -0.05)

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Spectra

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Spectra have been created for each power-law segment in the best fitting light curve (shown above). Times of flaring have not been removed, however this makes little difference to most spectra (see Fig 7/8c of Evans et al. 2009). For more information see the time-resolved spectroscopy documentation.

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phase1 spectrum (T0 + 9223372036854775807 to 65 s)

Download spectral files for phase1 spectrum.

Plots to download


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phase2 spectrum (T0 + 72 to 7128 s)

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Plots to download

WT and PC mode spectra of GRB 110731A

WT mode. Mean photon arrival: T0+246 s

NH (Galactic)1.65 × 1021 cm-2
NH (intrinsic)4.4 (+3.1, -3.0) × 1021 cm-2
z of absorber2.83
Photon index1.88 (+0.04, -0.04)
Flux (0.3-10 keV)
(Observed)
6.91 (+0.18, -0.17) × 10-10 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
8.90 (+0.18, -0.18) × 10-10 erg cm-2 s-1
Counts to flux (obs)3.67 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)4.73 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
687.75 (676)
Spectrum exposure573 s

PC mode. Mean photon arrival: T0+2455 s

NH (Galactic)1.65 × 1021 cm-2
NH (intrinsic)3.6 (+10.0, -3.6) × 1021 cm-2
z of absorber2.83
Photon index1.76 (+0.12, -0.10)
Flux (0.3-10 keV)
(Observed)
6.8 (+0.6, -0.5) × 10-11 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
8.4 (+0.5, -0.5) × 10-11 erg cm-2 s-1
Counts to flux (obs)4.01 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)4.95 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
335.12 (376)
Spectrum exposure1.8 ks

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phase3 spectrum (T0 + 7128 to 2092691 s)

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PC mode spectrum of GRB 110731A

PC mode. Mean photon arrival: T0+122338 s

NH (Galactic)1.65 × 1021 cm-2
NH (intrinsic)7 (+6, -4) × 1022 cm-2
z of absorber2.83
Photon index1.96 (+0.25, -0.22)
Flux (0.3-10 keV)
(Observed)
3.6 (+0.5, -0.4) × 10-13 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
5.44 (+1.00, -0.64) × 10-13 erg cm-2 s-1
Counts to flux (obs)3.99 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)6.10 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
311.41 (295)
Spectrum exposure73.6 ks

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Comparison with other bursts

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Parameter distributions

The plots below show the probability density functions of the temporal and time-averaged spectral parameters for all GRBs, with the data for GRB 110731A shown on in colour. Click the images for larger versions.

For all plots, the solid vertical lines mark the values for this GRB, and the dashed lines the 1-σ uncertainties. For α and Tb, the colour changes for each phase. For the spectral parameters, the WT fits are shown in blue and the PC in red. These figures correspond to Figs. 5,6, 7a and 8a of Evans et al. (2009). See the PDF documentation for more information.

Temporal indicesBreak TimesNHSpectral indices
Comparison of decay indices Comparison of light curve break times Comparison of intrinsic column densities Comparison of spectral energy indices

Closure Relationships

The plots below show (α, β) scatter plots for each of the different types/phases of light curves (see light-curve types), since GRB 110731A is of type, "Oddball," which has no scatter plots of its own. GRB 110731A is shown in colour, with each light curve phase, or XRT mode marked by a different colour. α and β are the temporal and spectral energy power-law indices respectively. The shaded regions mark those allowed by the standard closure relationships. These figures correspond to Fig. 10 of Evans et al. (2009). See the closure relationship documentation for more information.

No break
Comparison of nobreak closures
One-break, steep first
Steep phase
One-break, steep first
Shallow phase
Comparison of One-break, steep first, steep phase closuresComparison of One-break, steep first, shallow phase closures
One-break, shallow first
Shallow phase
One-break, shallow first
Steep phase
Comparison of One-break, shallow first, shallow phase closuresComparison of One-break, shallow first, steep phase closures
Canonical
Steep phase
Canonical
Plateau
Canonical
'Normal'
Canonical
Post jet-break
Comparison of Canonical, steep phase closuresComparison of Canonical, plateau phase closuresComparison of Canonical, normal phase closuresComparison of Canonical, post jet-break phase closures

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