A detailed spectral and morphological study of the gamma-ray supernova remnant RX J1713.7–3946 with HESS

Abstract

Aims. We present results from deep observations of the Galactic shell-type supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) conducted with the complete HESS array in 2004.

Methods. Detailed morphological and spatially resolved spectral studies reveal the very-high-energy (VHE – Energies E > 100 GeV) gamma-ray aspects of this object with unprecedented precision. Since this is the first in-depth analysis of an extended VHE gamma-ray source, we present a thorough discussion of our methodology and investigations of possible sources of systematic errors.

Results. Gamma rays are detected throughout the whole SNR. The emission is found to resemble a shell structure with increased fluxes from the western and northwestern parts. The differential gamma-ray spectrum of the whole SNR is measured over more than two orders of magnitude, from 190 GeV to 40 TeV, and is rather hard with indications for a deviation from a pure power law at high energies. Spectra have also been determined for spatially separated regions of RX J1713.7-3946. The flux values vary by more than a factor of two, but no significant change in spectral shape is found. There is a striking correlation between the X-ray and the gamma-ray image. Radial profiles in both wavelength regimes reveal the same shape almost everywhere in the region of the SNR.

Conclusions. The VHE gamma-ray emission of RX J1713.7-3946 is phenomenologically discussed for two scenarios, one where the gamma rays are produced by VHE electrons via Inverse Compton scattering and one where the gamma rays are due to neutral pion decay from proton-proton interactions. In conjunction with multi-wavelength considerations, the latter case is favoured. However, no decisive conclusions can yet be drawn regarding the parent particle population dominantly responsible for the gamma-ray emission from RX J1713.7-3946.

Astronomy & Astrophysics 449, 223-242 (2006)
ArXiv pre-print

Auxiliary informations

H.E.S.S. image shown in Figure 7

FITS image

Remark: Gamma-ray excess image smoothed with Gaussian, see paper caption.

H.E.S.S. data points for Figure 8

 r1      r2     Events / arcmin^2   Error
 (degrees)
0.00    0.07           1.62         0.29
0.07    0.14           1.70         0.16
0.14    0.21           1.96         0.13
0.21    0.28           2.46         0.12
0.28    0.35           2.30         0.10
0.35    0.42           2.48         0.09
0.42    0.49           2.17         0.08
0.49    0.56           1.33         0.07
0.56    0.63           0.53         0.06
0.63    0.70           0.31         0.05

Remarks: H.E.S.S. radial profile of the whole SNR, right panel of the figure. r1 and r2 are the bin edges. Errors are statistical only.

H.E.S.S. image shown in Figure 9

FITS image

Remark: File contains all three energy bands, see paper caption. Images are gamma-ray excess images smoothed with a Gaussian.

H.E.S.S. data points for Figure 10

  r1       r2     Ev/arcmin^2  Error    Ev/arcmin^2  Error    Ev/arcmin^2  Error
  (degrees)            (small E)             (medium E)            (large E)
0.000    0.085       0.40      0.15        0.36      0.10        0.41      0.08
0.085    0.170       0.54      0.09        0.46      0.06        0.49      0.05
0.170    0.255       0.61      0.07        0.66      0.05        0.65      0.04
0.255    0.340       0.73      0.06        0.67      0.04        0.65      0.03
0.340    0.425       0.56      0.05        0.70      0.04        0.74      0.03
0.425    0.510       0.56      0.05        0.65      0.04        0.56      0.03
0.510    0.595       0.31      0.04        0.24      0.03        0.26      0.02
0.595    0.680       0.13      0.04        0.11      0.02        0.13      0.02
0.680    0.765       0.07      0.04        0.09      0.02        0.07      0.01
0.765    0.850       0.07      0.03        0.06      0.02        0.03      0.01

Remarks: r1 and r2 are the bin edges in degrees, the number of events per unit area and the statistical errors are then given for the three energy bands, see paper caption.

H.E.S.S. data points for Figure 12

 #    E     E_1   E_2      Flux      Error_low   Error_high   SysError

   | ----  (TeV)  ---- | ------- (TeV^-1 cm^-2 s^-1) --------  |  (%)

 1   0.21   0.19  0.23   3.0585e-10   9.08508e-11 9.09567e-11     19 
 2   0.25   0.23  0.28   2.32993e-10  4.90308e-11 4.90749e-11     18 
 3   0.31   0.28  0.34   2.01682e-10  2.85643e-11 2.85995e-11      7 
 4   0.37   0.34  0.41   1.50293e-10  1.6932e-11  1.69527e-11      7 
 5   0.45   0.41  0.50   8.95475e-11  1.03033e-11 1.03167e-11      5 
 6   0.55   0.50  0.60   7.32618e-11  6.519e-12   6.52612e-12      4 
 7   0.66   0.60  0.73   4.15865e-11  4.1768e-12  4.18106e-12      3 
 8   0.80   0.73  0.88   3.27591e-11  2.75617e-12 2.7591e-12       2 
 9   0.97   0.88  1.06   2.21692e-11  1.81651e-12 1.81831e-12      8 
10   1.18   1.06  1.29   1.38065e-11  1.27624e-12 1.27756e-12      1 
11   1.42   1.29  1.56   7.49771e-12  8.9037e-13  8.91565e-13      5 
12   1.72   1.56  1.89   5.72041e-12  6.45068e-13 6.45818e-13      2 
13   2.09   1.89  2.28   3.77758e-12  4.39694e-13 4.40272e-13      3 
14   2.52   2.28  2.77   2.83056e-12  2.97667e-13 2.97847e-13      6 
15   3.06   2.77  3.35   1.53246e-12  2.08166e-13 2.08376e-13      2 
16   3.70   3.35  4.05   9.1268e-13   1.45226e-13 1.45447e-13      5 
17   4.48   4.05  4.91   6.85939e-13  9.84761e-14 9.85418e-14      2 
18   5.42   4.91  5.94   5.62568e-13  6.77122e-14 6.76072e-14      7 
19   6.56   5.94  7.19   3.05537e-13  4.74671e-14 4.74247e-14      1 
20   7.95   7.19  8.70   1.80534e-13  3.01942e-14 3.01021e-14      6 
21   9.62   8.70 10.53   1.09851e-13  2.21607e-14 2.21087e-14      1 
22  11.64  10.53 12.75   4.83884e-14  1.43372e-14 1.43215e-14     10 
23  15.72  12.75 18.69   1.37133e-14  5.8822e-15  5.90386e-15      7 
24  23.04  18.69 27.39   5.35252e-15  2.35438e-15 2.34355e-15      9 
25  33.76  27.39 40.14   3.53078e-15  1.12459e-15 1.07039e-15      6

Remarks: Flux points of the 2004 data, numbered 1 to 25. E is the energy the point is centred on, E_1 and E_2 give the corresponding energy range. Statistical errors are upward and downward ones, the systematic errors are in percent and from background uncertainties and the spectral technique only, determined as described in the paper. The global uncertainty on the energy scale is 20% and not included here.

Coordinates of the 14 regions used in Figure 14

Region #   |   RA (degrees)   |   Dec (degrees)

    1             257.892            -40.02
    2             257.892            -39.76
    3             257.892            -39.50
    4             258.227            -40.15
    5             258.227            -39.89
    6             258.227            -39.63
    7             258.227            -39.37
    8             258.561            -40.15
    9             258.561            -39.89
   10             258.561            -39.63
   11             258.561            -39.37
   12             258.898            -40.02
   13             258.898            -39.76
   14             258.898            -39.50

H.E.S.S. data points for Figure 16

 r1   r2     Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error      Ev/arcmin^2 Error
(degrees)	  region 1               region 2               region 3               region 4               region 5               region 6               region 7               region 8
0.00 0.06       0.77     0.82          1.02     0.88          2.81     1.03          4.09     1.24          0.95     0.84          0.03     0.78          2.25     0.98          1.74     1.00
0.06 0.12       2.00     0.58          1.12     0.52          1.63     0.56          1.12     0.52          1.28     0.54          1.73     0.56          1.77     0.57          1.98     0.58
0.12 0.18       2.16     0.45          2.37     0.45          2.59     0.47          0.62     0.37          1.08     0.39          2.00     0.44          1.98     0.44          1.73     0.43
0.18 0.24       2.04     0.38          2.12     0.38          1.55     0.36          1.64     0.36          2.16     0.38          2.64     0.40          2.96     0.41          3.18     0.42
0.24 0.30       2.54     0.35          1.97     0.33          1.33     0.30          1.61     0.31          2.90     0.36          2.85     0.36          2.84     0.36          3.51     0.38
0.30 0.36       2.89     0.33          1.80     0.29          0.73     0.26          2.08     0.30          2.93     0.33          3.07     0.33          3.23     0.34          2.79     0.33
0.36 0.42       2.23     0.28          2.26     0.28          1.00     0.24          2.34     0.29          2.96     0.30          3.32     0.31          3.84     0.33          2.35     0.29
0.42 0.48       2.39     0.27          2.14     0.26          1.72     0.25          1.68     0.25          2.35     0.27          2.92     0.28          3.50     0.30          1.93     0.26
0.48 0.54       1.39     0.23          1.74     0.24          1.38     0.23          1.38     0.23          1.44     0.23          1.84     0.24          2.10     0.25          1.17     0.22
0.54 0.60       0.40     0.19          1.17     0.21          1.05     0.21          0.46     0.19          0.97     0.21          0.76     0.20          0.88     0.20          0.82     0.20

Remarks: H.E.S.S. radial profiles for the eight regions given in the paper. Errors are statistical only.

H.E.S.S. data points for Figure 17

 az1  az2     Events     Error
 (degrees)    	         
-180  -150    330.4      27.5
-150  -120    278.9      26.2
-120   -90    184.2      24.0
 -90   -60    257.2      26.1
 -60   -30    291.7      26.4
 -30     0    308.4      27.0
   0    30    359.5      27.3
  30    60    296.7      26.5
  60    90    443.9      29.5
  90   120    524.9      30.2
 120   150    427.1      28.9
 150   180    404.7      28.2

Remarks: H.E.S.S. azimuth profile, right panel of the figure. Errors are statistical only. az1 and az2 are the bin edges. See paper caption for more details.

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