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Observation Date (UT) Observation Lat

Canonical Name:HESS J1841-055
TeVCat Name:TeV J1840-055
Other Names:ARGO J1839-0627
1HWC J1838-060
2HWC J1837-065
1E 1841-045
SNR Kes 73
Source Type:UNID
R.A.:18 40 55 (hh mm ss)
Dec.:-05 33 00 (dd mm ss)
Gal Long: 26.80 (deg)
Gal Lat: -0.20 (deg)
Distance:
Flux:0.4 (Crab Units)
Energy Threshold:540 GeV
Spectral Index:2.4
Extended:Yes
Size (X):0.41 (deg)
Size (Y):0.25 (deg)
Discovery Date:2007-07
Discovered By: H.E.S.S.
TeVCat SubCat:Default Catalog

Source Notes:

H.E.S.S. Galactic Plane Survey (HGPS, 2018):
A selection of information for each of the 78 sources in the HGPS is provided in TeVCat. For full details, visit the HGPS website.

Name: HESS J1841-055
Source Class: Unid
Identified Object: None
R.A. (J2000): 280.22 deg (18 40 51)
Dec. (J2000): -5.64 deg (-05 38 29)
Positional uncertainty: 0.104 deg
Spatial Model: 2-Gaussian
Size: 0.408 +/- 0.033 deg
Spectral Model: power law
Integral Flux > 1 TeV: 1.16e-11 +/- 1.36e-12 cm-2 s-1
Pivot Energy, E0: 1.05 TeV
Diff. Flux at E0: 1.38e-11 +/- 4.64e-13 cm-2 s-1 TeV-1
Spectral Index: 2.47 +/- 0.03
HGPS Source Notes:
Seven possible associations are listed in Table A.9. "This is a list of astronomical objects, extracted from catalogs of plausible counterparts, which are are found to be spatially coincident with the HGPS source":
- 2FHL J1840.9-0532e (2FHL)
- 3FGL J1840.9-0532e (3FGL)
- G26.6-0.1 (PWN)
- J1841-0524 (PSR)
- 3FGL J1839.3-0552 (3FGL)
- J1838-0537 (PSR)
- 3FGL J1838.9-0537 (3FGL)

Source position and its uncertainty:
From Bartoli et al. (2013):
- R.A. (J2000): 279.95 deg (18h 39m 48s)
- Dec. (J2000): -6.45 deg (-06d 27')
From Bartoli et al. (2013):
- R.A. (J2000): 18h 39m
- Dec. (J2000): -06d 3'
- the statistical errors in both directions are about 0.45deg
From Aharonian et al. (2008):
- RA: (J2000): 18 40 55
- Dec (J2000): -05 33 00
- The fit position has a statistical error of 0.05 deg

Source Extent:
From MAGIC Collaboration (2020):
- "The results of the detailed analysis show that the observed gamma-ray emission
from HESS J1841-055 is significantly extended. The estimated extension of the
source using MAGIC data is similar to that reported by the H.E.S.S. Collaboration,
found to be ∼ 0.4deg assuming a Gaussian distribution."
From Bartoli et al. (2013):
- Parameterizing the source shape with a two-dimensional Gaussian
function, the extension is estimated to be 0.40 +0.32 -0.22 deg.
From The ARGO-YBJ Collaboration (2013):
- "Most of the excess overlaps the extended region of the unidentified
source HESS J1841-055 even if the peak position is slightly displaced
from the center of HESS J1841-055 (Aharonian et al. 2008)"
From Aharonian et al. (2008):
- semi-major axis: 0.41 +/- 0.04 deg
- semi-minor axis: 0.25 +/- 0.02 deg
- angle: 39 +/- 6 deg
...measured counter-clk relative to RA axis
From The ARGO-YBJ Collaboration (2013):
- extension of 0.40 +0.32 -0.22 degrees

Spectral Properties:
From MAGIC Collaboration (2020):
The assumed spectrum of the source is considered to follow a
simple powerlaw, dN/dE = N0 (E/E0)^-A with:
- Spectral index, A: 2.57 +/- 0.0
- No: 9.43 +/- 0.29 x10e-12 TeV-1 cm-2 s-1

From Aharonian et al. (2008):
- Spectral index: 2.4 +/- 0.1(stat) +/- 0.2(sys)
From The ARGO-YBJ Collaboration (2013):
- Spectral index: 2.32 +/- 0.23

Flux:
From MAGIC Collaboration (2020):
The gamma-ray flux above 50 GeV is, F(> 50 GeV) = 2.23 × 10e-10 cm-2 s-1

From Aharonian et al. (2008):
- 12.8 +/- 1.3 x 10e-12 (cm-2 s-1 TeV-1) between 0.54 and 80 TeV
- according to The ARGO-YBJ Collaboration (2013), this corresponds
to about 40.3% of the Crab unit

From The ARGO-YBJ Collaboration (2013):
- "The integral gamma-ray flux above 1 TeV is 1.3 +/- 0.4 Crab units,
which is 3.2-+1.0 times the flux derived by HESS."
- "This discrepancy, already found in the observation of other
extended sources, could origin from the different techniques used in
the background estimation for extended sources with ARGO-YBJ and HESS
data." (This is discussed further in the reference.)

Source Classification:

From Cao et al. (2021):
- HESS J1841-055 may be associated with LHAASO J1839-0545

From MAGIC Collaboration (2020):
- "We find that the extended emission at GeV-TeV energies is best described by more
than one source model."
- "There are several bright hot-spots in the extension of the source which appears to
be multiple sources which contribute to the observed emission at GeV-TeV energies."
- "We also perform the first energy-dependent analysis of the HESS J1841-055 region
at GeV-TeV. We find that the emission at lower energies comes from a diffuse or extended
component, while the major contribution of gamma rays above 1 TeV arises from the
southern part of the source."
- "The spectral curvature of the SED in the energy range from GeV–TeV is significant
and it can either be described by a broken powerlaw model with break at 37 GeV or a
powerlaw with exponential cutoff at 1.8 TeV"
- "The first multiwavelength spectral energy distribution of this unidentified source
shows that the emission at GeV-TeV energies can be well explained with both leptonic
and hadronic models. For the leptonic scenario, bremsstrahlung is the dominant emission
compared to inverse Compton. On the other hand, for the hadronic model, gamma-ray
resulting from the decay of neutral pions can explain the observed spectrum. The
presence of dense molecular clouds overlapping with HESS J1841-055 makes both
bremsstrahlung and pi-0-decay processes the dominant emission mechanisms for the source."
- "Within the present morphological and spectral studies of this extended source using
GeV-TeV data and available MWL information on sources present within the region, we
conclude that the extended gamma-ray emission seems to be associated with multiple sources
in this region. The GeV–TeV emission is compatible with a PWN scenario, although a fraction
of the gamma-ray emission can also be explained within a SNR scenario"

From Abeysekara et al. (2017):
- "2HWC J1837-065 is the principal maximum of an elongated region
containing multiple known extended sources which are not resolved in
the present analysis."
- " This elongated HAWC region also covers the location of the
unidentified H.E.S.S. source HESS J1841-055, which is a very complex
TeV gamma-ray source with many potential counterparts ..."
From Yeung et al. (2017):
- "The Kes 73/1E 1841-045 system has a distance of 8.5 +1.3 −1.0 kpc
from us and an age of 750- 2100 yr (Tian & Leahy 2008; Kumar et al. 2014)
This system is potentially responsible for particle acceleration, as
it shows intense TeV emission at the northern edge of HESS J1841-055
(Aharonian et al. 2008; Bochow 2011)."
- The authors detect an extended GeV source positionally consistent
with this system which they name Fermi J1841.1-0458.
- "Our analysis of Fermi J1841.1-0458 confirms what Acero et al. (2016)
and Li et al. (2017) discovered with Fermi LAT data: the
presence of a GeV-bright extended source which is positionally
consistent with the Kes 73/1E 1841-045 system."
- Two spectral components are proposed to describe the Fermi LAT data
which the authors suggest is due to the source being dominated by the
magnetar 1E 1841-045 below 10 GeV and possibly to an SNR or to a PWN
at energies above 10 GeV
- "Since Kes 73 is as young as RX J1713.7-3946 and is just slightly
younger than RX J0852.0-4622, it is likely that Kes 73 dominates the
VHE emission of Fermi J1841.1-0458, whose VHE spectrum is as hard as
those of RX J0852.0-4622 and RX J1713.7-3946. ...
... HESS observation in the TeV band shows that Kes 73 has a detection
significance of ∼6.0 sigma at the northern edge of HESS J1841-055
(cf. Aharonian et al. 2008; Bochow 2011). Unfortunately, it is
inappropriate to examine the spectral connection for Fermi
J1841.1-0458 and HESS J1841-055, since HESS J1841-055 has an extended
feature composed of Kes 73 as well as several stronger high-energy
sources (Aharonian et al. 2008; Bochow 2011). It is unclear whether
the VHE spectrum of Fermi J1841.1-0458 can be connected to the TeV
spectrum of Kes 73 (after subtracting other components of HESS
J1841-055) with a turnover and peak at ∼300 GeV, like what is observed
in the spectra of RX J0852.0-4622 and RX J1713.7-3946. It is still
dubious whether the scenarios explaining the GeV spectra of RX
J0852.0-4622 and RX J1713.7-3946 can be applied to Kes 73 or not."
-"TeV-detected PWNe should be associated with pulsars releasing power
of >10e36 erg s−1 (Halpern & Gotthelf 2010). Such required power is
greater than the rotational power of 1E 1841-045 by three orders of
magnitude, but can be afforded by magnetic field decay of 1E 1841-045
...
... Therefore, 1E 1841-045 is sufficient to generate an IC-radiating
PWN which may account for a significant portion of the LAT flux in the
VHE band and/or the HESS flux in the TeV band. However, a major
uncertainty of this scenario is that there is no firmly identified PWN
inside the SNR shell of Kes 73."
From Abeysekara et al. (2015):
- "1HWC J1838-060 is detected at 6.1sigma post trials and is located
in the middle of the known TeV sources HESS J1837-069 and HESS
J1841-055"
From Nobukawa et al. (2015):
- Suzaku observations, which covered half of the region of the HESS
sources were undertaken.
- In the soft band (0.5-2.0 keV), diffuse emission was detected from
Suzaku J1840.2-0552, postulated to be a supernova remnant.
- "We also discovered an extended source, Suzaku J1840.2-0544, in the
hard band (2.0-8.0 keV) with an emission line at 6.1 keV. From the
spectral feature and large interstellar absorption, this source is
likely to be a cluster of galaxies behind the Galactic plane at the
red-shift of ∼0.09. The other diffuse source spatially overlaps with
the SNR candidate G26.6-0.2, which shows a non-thermal dominant
spectrum. Since no other candidate is found in the hard X-ray band, we
infer that these largely extended sources could be possible
counterparts of HESS J1841-055."
From Acero et al. (2013):
- Analysis of the LAT data from this source leads to its
classification as a PWN candidate
From Tibolla et al. (2011):
- they suggest that this source could contain an ancient PWN
From The ARGO-YBJ Collaboration (2013):
- "The extended morphology of HESS J1841-055 and the presence of
several sources within the 90% confidence error region suggests
contributions from more than one of them, but so far no clear
counterparts in lower-energy wavebands can be identified. However, the
possibility of a GeV-TeV gamma-ray source without any counterpart can not
be excluded. Both leptonic and hadronic productions of gamma rays have
been proposed, but it is not easy to distinguish between the two
contributions basing only on the gamma-ray data. The current upper limits
to the neutrino flux from the HESS J1841-055 region are too high to
test the hadronic model. Further multiwavelength observations from
radio to GeV energies and data from neutrino telescopes of suitable
sensitivity are needed in order to disentangle between the different
emission possibilities."


Seen by: H.E.S.S., ARGO-YBJ, HAWC, MAGIC
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