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Page
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under
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construction.
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This
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page
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summarize
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the
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main
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points
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of
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the
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analysis
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I
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did
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on
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HESS
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J1857+026
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using
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to
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sample
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of
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data.
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The
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first
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analysis
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used
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31
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months
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of
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data
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collected
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from
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August
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4,
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2008,
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until
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March
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2011.
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Only
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gamma-rays
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in
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the
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Diffuse
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class
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events
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were
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selected
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and
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we
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excluded
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those
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coming
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from
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a
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zenith
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angle
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larger
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than
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100°.We
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have
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used
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the
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P6_V11_Diffuse
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instrument
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response
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functions
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(IRFs).
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We
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included
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in
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the
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model
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all
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the
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sources
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of
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the
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18
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month
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catalog
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and
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assiociated
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diffuse
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files.
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The
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second
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analysis
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used
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the
...
same
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amount
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of
...
data.
...
Only
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gamma-rays
...
in
...
the
...
source
...
class
...
events
...
were
...
selected
...
and
...
we
...
excluded
...
those
...
coming
...
from
...
a
...
zenith
...
angle
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larger
...
than
...
100°.
...
We
...
have
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used
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the
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P7_V6_SOURCE
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IRFs.
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We
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included
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in
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the
...
model
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all
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the
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sources
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of
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the
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2FGL
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catalog
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and
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assiociated
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diffuse
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files.
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The
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Region
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of
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Interest.
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HESS
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J1857+026
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is
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in
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the
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same
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region
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than
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the
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SNR
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W44
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which
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is
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the
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brightest
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source
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of
...
the
...
region. 
Fig 1. Counts map of the region above 6 GeV. Left Pass 6 analysis with 18 months catalog sources in green. Right : Same picture corresponding to the Pass 7 analysis with 2FGL sources represented in blue.
W44
The shape of W44 was fitted by an Elliptical Ring (ref. 1) and it spectra by a broken power law.
We saw an excess close to W44 and tried to refit the source to take into account this excess.
We refitted again the spectra of W44 by a Log-Parabola and studied the shape of W44.
The main point is that the results are consistent with previous work and with 2FGL cat.
Fig. 2. Comparison between the result of ref. 1 (red contours) and our results using pass 6 (white ring) . There is no error taken into account in this templates. Figure to be updated with Pass 7
Model | RA(°) | DEC(°) | Semi Major Axis (°) | Semi Minor Axis (°) | Pos.Ang.(°) |
283,990 | 1,355 | 0,300 | 0,190 | 327,000 | |
Pass 6 | 284.015(+/-0.004) |
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1.392(+/-0.005) |
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0.335(+0.117 |
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-0.086) |
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0.207 |
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(+0.023 |
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-0.021) |
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330+/ |
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- |
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25 | |
Pass 7 | 284.000(+/-0.006) |
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1.374(+/-0.006) |
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0.332(+0.109/-0.079) |
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0.205 |
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(+0.021/-0.017) |
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327 +/-22 |
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Table
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1.
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Parameters
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obtained
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by
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fiting
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the
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shape
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of
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W44.
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The
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main
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point
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is
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that
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all
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of
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these
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values
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are
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consistent
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with
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the
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work
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of
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Tanaka
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et
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al.
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2010.
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Fig.
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3
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SED
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of
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W44
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given
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by
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pointlike.
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Adding
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a
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new
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source
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to
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Pass
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7
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Analysis
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section
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under
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construction
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Using
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2FGL
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sources,
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Pass
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7
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IRFS
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and
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associated
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diffuses,
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we
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found
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a
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low
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energy
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excess
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quickly
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decreasing
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with
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energy.
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To
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prevent
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contamination
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from
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this
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source
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on
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HESS
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J1857
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we
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analysed
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it.
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The
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best
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fit
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we
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obtained
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is
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a
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point
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source
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located at
RA=283.58
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DEC=2.98
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Fig.
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4.
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Residual
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TS
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map
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between
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100MeV
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and
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1.3GeV
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using
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pointlike.
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Green
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crosses
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represents
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2FGL
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sources
Fig. 5. SED of the source using pointlike.
The best fit using gtlike provided the following parameters alpha = 3.5 +/- 0.2, beta = 0.6 +/- 0.1, Eb ? 1.2 GeV, and N_0 = (3.1 +/- 0.5) X 10^{-12} photons/MeV/cm^2/s.
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HESS
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1857+026
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Morphology
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above
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10GeV
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We
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made
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an
...
analysis
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of
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the
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morphology
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of
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HESS
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1857+026
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above
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10GeV.
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Three
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hypotheses
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were
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tested
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:
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point
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source,
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gaussian
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and
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disk.
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No
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significant
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extension
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was
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found
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as
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can
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be
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seen
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in
...
the
...
following
...
table.
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The
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delta
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show
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that
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we
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do
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not
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detect
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any
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extension
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of
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the
...
source.
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Hypothesis | Point | Gaussian | Disk | ||
|---|---|---|---|---|---|
TS | 33.38 | 41.35 | 42.21 | ||
Loglike | -48201.50 | -48197.55 | -48197.98 |
|
Table 2. TS and Loglike found above 10GeV for a point source, a gaussian and a Disk.
Fig. 4. Excess TSMap of a 10° * 10° roi around HESS 1856+026.
Fig. 5 Zoom of the previous TS map with a factor of 5. The green square represent an 2° * 2° roi and the green contours are those of HESS source.
Bibliography :
(1) Abdo et al., Science, 327, 1103-1106, 2010