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Observation Date (UT) Observation Lat

Canonical Name:HESS J1831-098
TeVCat Name:TeV J1831-099
Other Names:PSR J1831-952
2HWC J1831-098
1LHAASO J1831-1007u*
Source Type:PWN
R.A.:18 31 25 (hh mm ss)
Dec.:-09 54 00 (dd mm ss)
Gal Long: 21.85 (deg)
Gal Lat: -0.11 (deg)
Distance:
Flux:0.04 (Crab Units)
Energy Threshold:1000 GeV
Spectral Index:2.1
Extended:Yes
Size (X):0.15 (deg)
Size (Y):0.15 (deg)
Discovery Date:2011-10
Discovered By: H.E.S.S.
TeVCat SubCat:Newly Announced

Source Notes:

Source Position:

From Sheidaei et al. (2011):
- R.A. (J2000): 18h 31m 25s
- Dec. (J2000): -09d 54m
- no uncertainty on the source position is quoted

Source Extension:

From Sheidaei et al. (2011):
- a 2-d Gaussian gives a width of ~0.15deg

Spectral Properties:

From Sheidaei et al. (2011):
- Spectral index: 2.1 +/- 0.1

Source Association:

From Fang et al. (2022):
- HESS J1831-098 is the pulsar halo of PSR J1831-0952. This source was
first discovered by the High Energy Spectroscopic System (H.E.S.S) and
was considered an old PWN at that time (Sheidaei et al., 2011).
However, Fang et al. (2022) point out that it is more reasonable to
regard it as a pulsar halo as it passes all the criteria introduced
above. Although this source is more than 10 times farther than
Geminga, the significantly stronger injection power ensures its
visibility.

From Fang et al. (2022):
- "HESS J1831-098 is a candidate pulsar halo observed by both
H.E.S.S. and HAWC experiments. We adopt the flux map of the
H.E.S.S. Galactic plane survey and the spectrum measurements of
H.E.S.S. and Fermi-LAT to study HESS J1831-098. We find that
HESS J1831-098 meets all the criteria for a pulsar halo."

From Linden et al. (2017):
- the authors propose that this object is a member of a new class of
TeV emitters - "extrended TeV halos"
- "Observations by HAWC and Milagro have detected bright and spatially
extended TeV gamma-ray sources surrounding the Geminga and Monogem
pulsars. We argue that these observations, along with a substantial
population of other extended TeV sources coincident with pulsar wind
nebulae, constitute a new morphological class of spatially extended
TeV halos."

From Abeysekara et al. (2017):
- "2HWC J1831-098 may be associated with the TeV source HESS J1831-098
(distance of 0.01 deg)."
- the H.E.S.S. source "is a candidate PWN powered by the nearby 67 ms
pulsar PSR J1831-0952 (E-dot of 1.1 10e36 erg s-1, distance of 3.7
kpc, characteristic age of 128 kyr)."
- "The differential flux at 7 TeV measured by HAWC is two to five
times larger than the one reported by H.E.S.S., depending on the
source size used in the spectrum fit."
- "The indices measured by HAWC are also softer than the value
reported by H.E.S.S., -2.1 +/- 0.1."

From Sheidaei et al. (2011):
- "although no PWN has been detected so far at other wavebands, the interpretation of
HESS J1831-098 in terms of a wind nebula remains the most likely scenario, given the
spatial coincidence with the energetic PSR J1831-0952, the reasonable efficiency and
observed abundance of such PWN-type VHE sources."

A PeVatron:

From Cao et al. (2024):
- This source is listed as being a UHE source in Table 2. This means
that it has a detection above 100 TeV at a significance level
corresponding to a test statistic of greater than 20.


Seen by: H.E.S.S., HAWC, LHAASO
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