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Observation Date (UT) Observation Lat

Canonical Name:HESS J1813-178
TeVCat Name:TeV J1813-178
Other Names:G12.82-0.02
PSR J1813-1749
CXOU J181335.1-174957
IGR J18135-1751
W33
2HWC J1814-173
Source Type:PWN
R.A.:18 13 36.0 (hh mm ss)
Dec.:-17 50 24 (dd mm ss)
Gal Long: 12.81 (deg)
Gal Lat: -0.03 (deg)
Distance: 4.7 kpc
Flux:0.06 (Crab Units)
Energy Threshold:200 GeV
Spectral Index:2.09
Extended:Yes
Size (X):0.04 (deg)
Size (Y):0.04 (deg)
Discovery Date:2005-03
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 J1813-178
Source Class: Composite
Identified Object: PSR J1813-1749
R.A. (J2000): 273.40 deg (18 13 36)
Dec. (J2000): -17.83 deg (-17 50 03)
Positional uncertainty: 0.015 deg
Spatial Model: Gaussian
Size: 0.049 +/- 0.004 deg
Spectral Model: power law
Integral Flux > 1 TeV: 2.12e-12 +/- 3.98e-13 cm-2 s-1
Pivot Energy, E0: 1.40 TeV
Diff. Flux at E0: 1.01e-12 +/- 5.60e-14 cm-2 s-1 TeV-1
Spectral Index: 2.07 +/- 0.05
HGPS Source Notes:
This is one of the 31 firmly-identified objects among the HGPS sources. Three 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":
- J1813-1749 (PSR)
- G12.8-0.0 (COMP)
- G12.7-0.0 (SNR)

Source position and its uncertainty:
From Aharonian et al. (2006):
- l: 12.813 +/- 0.005 (deg)
- b: -0.0342 +/- 0.005 (deg)
- R.A. (deg): 273.40 (Convert to HMS: 18 13 36.0)
- Dec. (deg): -17.84 (Convert to HMS: -17 50 24)

Source Extent:
From Aharonian et al. (2006):
- radius: 0.036 +/- 0.006 deg

Source Association:

From H.E.S.S. Collaboration (2024):
- The source is described by two emission components, HESS J1813-178A and HESS J1813-178B:
- HESS J1813-178A:
... Spectral index: 2.17 ± 0.05stat ± 0.03sys
... Flux at 1 TeV (10 e-12 cm-2 s-1 TeV-1): 3.16 ± 0.18stat ± 0.24sys
... R.A. (J2000, deg): 273.400 ± 0.004stat ± 0.001sys
... Dec. (J2000, deg): -17.831 ± 0.004stat ± 0.001sys
... Major axis Gaussian (deg): 0.056 ± 0.003stat ± 0.001sys
- HESS J1813-178B:
... Spectral index: 2.36 ± 0.09stat ± 0.05sys
... Flux at 1 TeV (10 e-12 cm-2 s-1 TeV-1): 9.89 ± 1.40stat ± 1.23sy
... R.A. (J2000, deg): 273.61 ± 0.06stat ± 0.07sys
... Dec. (J2000, deg): -17.39 ± 0.07stat ± 0.08sys
... Major axis Gaussian (deg): 0.72 ± 0.08stat ± 0.09sys
... Eccentricity: 0.80 ± 0.06stat ± 0.04sys
... Offset (deg): 40 ± 7stat ± 6sys
- more details below.
- "We performed a likelihood-based analysis on 32 hours of
H.E.S.S. data and 12 yr of Fermi-LAT data and we fitted a
spectro-morphological model to the combined datasets. These results
allowed us to develop a physical model for the origin of the observed
gamma-ray emission in the region."
- "In addition to the compact very-high-energy gamma-ray emission
centred on the pulsar, we find a significant yet previously undetected
component along the Galactic plane. With Fermi-LAT data, we confirm
extended high-energy emission consistent with the position and
elongation of the extended emission observed with H.E.S.S. These
results establish a consistent description of the emission in the
region from GeV energies to several tens of TeV."
- "This study suggests that HESS J1813-178 is associated with a
gamma-ray PWN powered by PSR J1813-1749. A possible origin of the
extended emission component is inverse Compton emission from electrons
and positrons that have escaped the confines of the pulsar and form a
halo around the PWN."
- "The compact emission can be accounted for using a Gaussian model, centred
at a position of RA = (273.396 ± 0.004) deg , Dec = (-17.831 ±0.004) deg and
σ = (0.056 ± 0.003) deg , hereafter referred to as HESS J1813−178A. The
emission is well described with a power-law spectral model and detected with
a significance of 38σ. The best-fit position and extension derived in this
analysis are compatible with the results reported in Aharonian et al. (2006)
- The second emission component: "This study finds that an elongated Gaussian
model centred at RA = (273.61 ± 0.06) deg , Dec = (−17.39 ± 0.07) deg with
a semi-major axis of σ = (0.72 ± 0.08) deg describes the emission best.
The gaussian model is preferred over the disc-like model with ∆TS = 59.91,
while the elongated Gaussian model is preferred by 3.4σ compared to the
symmetric Gaussian model. The increased size compared to the first report
of possible extended emission can be attributed to the difference in
background estimation. A power-law model was used to describe the emission.
This additional extended emission, hereafter referred to as HESS J1813−178B,
was detected with a significance of 13σ"
- "The morphology of HESS J1813−178B is in good spatial agreement with
the extended emission 3HWC J1813−174 observed by HAWC, as well as
1LHAASO J1814−1719u*, extended emission observed by the WCDA of
LHAASO"
- "We find, that the data from HESS J1813−178A, as well as HESS J1813−178B
can be described well by gamma-ray emission from synchrotron
and IC emission of electrons originating from the pulsar. This
indicates that HESS J1813−178A, is likely a PWN, while the extended
emission is possibly caused by electrons and positrons escaping the
confines of the PWN and diffusing into the ISM. "

From Guo & Xin (2024):
- "By analyzing the GeV gamma-ray data in the field of HESS J1813-178
using 14 yr of PASS 8 data recorded by the Fermi Large Area Telescope,
we report the discovery of three different sources with different
spectra in this region."
- "The hard source with a PL spectral index of 2.11 ± 0.08 has a small
size extension, which is spatially and spectrally coincident with the
TeV gamma-ray emission from HESS J1813-178."
- "CO observations display the dense molecular clouds surrounding
HESS J1813-178 in the velocity range of 45–60 km s−1."
- "The possible origins of the gamma-ray emission from HESS J1813-178
are discussed, including SNR G12.820.02, the PWN driven by the
energetic X-ray pulsar PSR J1813-1749 and YSC Cl 1813-178. However,
none of them can be ruled out clearly. Note that the maximum energy of
protons in the hadronic model should exceed a few hundred TeV, which
makes HESS J1813-178 a promising PeVatron."

From Camilo et al. (2021):
- "The 44.7 ms X-ray pulsar in the supernova remnant G12.82-0.02/HESS J1813-178
has the second highest spin-down luminosity of known pulsars in the Galaxy,
with E-dot=5.6e37 erg/s. Using the Green Bank Telescope, we have detected
radio pulsations from PSR J1813-1749 at 4.4-10.2 GHz. The pulse is highly
scattered, with an exponential decay timescale tau longer than that of any
other pulsar at these frequencies. "
- "A point source detected at this position by Dzib et al. in several observations
with the Jansky Very Large Array can be attributed to the pulsed emission."
- "The large dispersion measure, DM=1087 pc/cc, indicates a distance of either
6.2 or 12 kpc according to two widely used models of the electron density
distribution in the Galaxy. These disfavor a previously suggested association
with a young stellar cluster at the closer distance of 4.8 kpc. The high X-ray
measured column density of approx. 1e23/cm^2 also supports a large distance. If
at d approx. 12 kpc, HESS J1813-178 would be one of the most luminous TeV sources
in the Galaxy."

From Araya (2018)
- A detailed study of the GeV emission of the region around this
source and HESS J1809-193 was undertaken.
- The author postulates that HESS J1809-193 could be a protonpevatron.
- For HESS J1813-178 the author states:
- "we find a region of significant emission which is much more
extended than the TeV emission and whose spectrum is softer than
expected from a PWN but similar to those seen in several star forming
regions that are believed to accelerate protons. There is marginal
evidence for a GeV point source at the location of the X-ray PWN,
beside the extended emission."

From Abeysekara et al. (2017):
- "2HWC J1814-173 is close by and possibly associated with the TeV
source HESS J1813-178" at a distance of approx. 0.5deg
- "HESS J1813-178 is a candidate PWN, powered by the highly energetic
young pulsar PSR J1813-1749 located close to the center of supernova
remnant G12.82-0.02 (Gotthelf & Halpern 2009). PSR J1813-1749 has a
spindown luminosity E-dot of 6.8 10e37 erg s−1, a characteristic age
of 3.3–7.5 kyr (Gotthelf & Halpern 2009), and an estimated distance of
4.8 kpc (Halpern et al. 2012). Closer to the measured HAWC location is
SNR G013.5+00.2 (0.2 deg away), though it has not been detected in
gamma rays by H.E.S.S. or Fermi-LAT."

From Acero et al. (2013):
- "... no conclusion can be reached on the nature of the
H.E.S.S. emission being a PWN or a SNR. However, in light of the
different models discussed one can exclude a model assuming a
Maxwellian + power-law tail injection spectrum with an index of 2.4
with the parameters derived in Fang & Zhang (2010) in the PWN
scenario. These upper limits also constrain the hadronic model by
rejecting a power-law injection spectrum of 2.1 with the parameters
proposed by Funk et al. (2007b). Therefore, whatever the origin of the
gamma-ray emission, the injected spectrum of the primary electrons and
protons needs to be relatively hard in order to stay below the
Fermi-LAT upper limits (Spectral index ≤ 2.1)."

From Funk et al. (2007):
- "The NANTEN 12CO(J=1-0) observations show a giant molecular cloud of
mass 2.5 × 10^5 M0 at a distance of 4 kpc in the vicinity of HESS
J1813-178. Even though there is no direct positional coincidence, this
giant cloud may have influenced the evolution of the γ-ray source and
its surroundings. The X-ray data show a highly absorbed (nH ~ 1. ×
1023 cm-2) non-thermal X-ray emitting object coincident with the
previously known ASCA source AX J1813-178 exhibiting a compact core
and an extended tail towards the north-east, located in the centre of
the radio shell-type Supernova remnant (SNR) G12.82-0.02. This central
object shows morphological and spectral resemblance to a Pulsar Wind
Nebula (PWN) and we therefore consider that this object is very likely
to be a composite SNR. We discuss the scenario in which the gamma rays
originate in the shell of the SNR, and that in which they originate in
the central object, in terms of a time-dependent one-zone leptonic
model. We demonstrate, that in order to connect the core X-ray
emission to the VHE gamma-ray emission electrons have to be
accelerated to energies of at least 1 PeV."



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