| Canonical Name: | HESS J1702-420 |
| TeVCat Name: | TeV J1702-420 |
| Other Names: | HESS J1702-420A
HESS J1702-420B |
| Source Type: | UNID |
| R.A.: | 17 02 44 (hh mm ss) |
| Dec.: | -42 00 57 (dd mm ss) |
| Gal Long: | 344.30 (deg) |
| Gal Lat: | -0.18 (deg) |
| Distance: | |
| Flux: | 0.07 (Crab Units) |
| Energy Threshold: | 200 GeV |
| Spectral Index: | 2.07 |
| Extended: | Yes |
| Size (X): | 0.30 (deg) |
| Size (Y): | 0.15 (deg) |
| Discovery Date: | 2006-01 |
| 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 J1702-420 |
| Source Class: | Unid |
| Identified Object: | None |
| R.A. (J2000): | 255.63 deg (17 02 30) |
| Dec. (J2000): | -42.07 deg (-42 04 25) |
| Positional uncertainty: | 0.049 deg |
| Spatial Model: | Gaussian |
| Size: | 0.197 +/- 0.025 deg |
| Spectral Model: | power law |
| Integral Flux > 1 TeV: | 4.45e-12 +/- 3.57e-13 cm-2 s-1 |
| Pivot Energy, E0: | 1.70 TeV |
| Diff. Flux at E0: | 1.60e-12 +/- 1.21e-13 cm-2 s-1 TeV-1 |
| Spectral Index: | 2.09 +/- 0.07 |
| HGPS Source Notes: | |
| | |
This is one of eleven HGPS sources that "do not have any associations with known physical objects, although some are associated
with HE gamma-ray sources."
"HESS J1702−420 is near the point-like source 2FHL J1703.4−4145. The elongation of the VHE gamma-ray emission prevented the automated procedure from making
the association, but a connection between the objects seems plausible. The small size SNR G344.7−0.1 (about 8' in diameter) is also in the vicinity and in
good positional coincidence with the (point-like) 2FHL source"
Source position and its uncertainty:
From
Aharonian et al. (2006):
- l: 344.26 +/- 0.04 (deg)
- b: -0.22 +/- 0.03 (deg)
- R.A. (deg): 255.69 (Convert to HMS: 17 02 45.6)
- Dec. (deg): -42.07 (Convert to HMS: -42 04 12)
From
Aharonian et al. (2008):
- RA: (J2000): 17 02 44
- Dec (J2000): -42 00 57
- The fit position has a statistical error of 0.05 deg
Source Extent:
From
Giunti et al. for the H.E.S.S. Collaboration (2021):
HESS J1702-420A:
- "This object has a 1 sigma radius of 0.06 +/- 0.02 (stat) +/- 0.03 (sys) deg"
HESS J1702-420B:
- "This objet has an elongated shape"
From
Aharonian et al. (2006):
- radius: 0.08 +/- 0.04 deg
From
Aharonian et al. (2008):
- semi-major axis: 0.30 +/- 0.02 deg
- semi-minor axis: 0.15 +/- 0.01 deg
- angle: 68 +/- 7 deg
...measured counter-clk relative to RA axis
Multiple Components:
From
Giunti et al. for the H.E.S.S. Collaboration (2021):
- this source has been found to have two components: HESS J1702-420A and HESS J1702-420B
- "There are two overlapping objects, called HESS J1702-420A and HESS
J1702-420B, that together describe the emission from HESS J1702-420."
A PeVatron:
From
Mitchell (2021):
- this source is included in a list of Galactic sources currently known
to produce gamma-ray emission above 100 TeV.
From
Giunti et al. for the H.E.S.S. Collaboration (2021):
- "we report on new H.E.S.S. observations of the PeVatron candidate
HESS J1702-420, which bring evidence for the presence of gamma rays up
to 100 TeV. This is the first time in the history of H.E.S.S. that
photons with such high energy are observed."
- "Remarkably, the new deep observations allowed the discovery of a
new gamma-ray source component, called HESS J1702-420A, that was
previously hidden under the bulk emission traditionally associated
with HESS J1702-420. This new object has a power-law spectral
slope <2 and a gamma-ray spectrum that, extending with no sign of
curvature up to 100 TeV, makes it an excellent candidate site for the
presence of PeV-energy cosmic rays."
Spectral Information:
From
Giunti et al. for the H.E.S.S. Collaboration (2021):
HESS J1702-420A:
- This object has a spectral index of 1.53 +/- 0.19 (stat) +/- 0.20 (sys)
and a gamma-ray spectrum that, extending with no sign of curvature up
to at least 64 TeV (possibly 100 TeV), makes it a compelling candidate
site for the presence of extremely high energy cosmic rays. With a flux
of 2.08 +/- 0.49 (stat) +/- 0.62 (sys) x10e-13 cm-2 s-1 above 2 TeV and
a 1 sigma radius of 0.06 +/- 0.02 (stat) +/- 0.03 (sys) deg
HESS J1702-420B:
- "HESS J1702-420A is outshone below approx. 40 TeV by the companion
HESS J1702-420B. The test of a point-source hypothesis for HESS J1702-420A
resulted in a non-convergence of the fit. HESS J1702-420B has a steep
spectral index of 2.62 +/- 0.10 (stat) +/- 0.20 (sys), elongated shape
and a flux above 2 TeV of 1.57 +/- 0.12 (stat) +/- 0.47 (sys) x10-12 cm-2 s-1
that accounts for most of the low-energy HESS J1702-420 emission."
Source Association:
From
Eagle et al. (2020):
- "We report on the investigation of a very high energy, Galactic gamma-ray source recently
discovered at >50 GeV using the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope."
- "This object, 2FHL J1703.4-4145, displays a very hard >50 GeV spectrum with a photon index of
approx. 1.2 in the 2FHL catalog and, as such, is one of the most extreme sources in the 2FHL
sub-sample of Galactic objects."
- "A detailed analysis of the available multi-wavelength data shows that this source is located on
the western edge of the supernova remnant (SNR) G344.7–0.1, along with extended TeV source,
HESS J1702-420."
- "The observations and the spectral energy distribution modeling support a scenario where this
gamma-ray source is the byproduct of the interaction between the SNR shock and the dense
surrounding medium, with escaping cosmic rays (CRs) diffusing into the dense environment and
interacting with a large local cloud, generating the observed TeV emission."
- eIf confirmed, an interaction between the SNR CRs and a nearby cloud would make 2FHL J1703.4-4145
another promising candidate for efficient particle acceleration of the 2FHL Galactic sample,
following the first candidate from our previous investigation of a likely shock-cloud interaction
occurring on the West edge of the Vela SNR."
From
Lau et al. (2019):
From the abstract:
- "The unidentified TeV gamma-ray source HESS J1702-420 has no firm
associations with any counterparts at other wavelengths. We present an
analysis of the interstellar medium using results from the Mopra
Southern Galactic Plane CO survey and archival H I data from the
Southern Galactic Plane Survey."
- "We find significant components of molecular and atomic gas
overlapping the TeV gamma-ray source at several velocities along the
line of sight, with masses approx. 10e2-10e4 M_solar and densities up
to approx. 10e3 cm-3. Potentially interesting and favourable
morphological correspondences between the ISM and the TeV gamma-ray
emission were found, and in a hadronic scenario, we find that cosmic
ray (CR) enhancement values of approx. 100 times the local solar
values are required to produce the TeV gamma rays."
- "We investigate the separate scenarios in which HESS J1702-420 is
powered by the nearby SNR G344.7-0.1, PSRJ1702-4128, and an unknown
accelerator."
- "No evidence in the ISM was found to link the SNR with the TeV
source."
- "While the morphology of the gas located at the dispersion distance
of PSRJ1702-4128 did not discount the possibility of a leptonic
origin, the required energetics and the broad and hard TeV spectrum
would likely disfavour such a scenario."
- "Given the presence of potentially favourable ISM overlapping HESS
J1702-420, we additionally speculate on the plausibility of scenarios
involving undetected CR accelerators."
From
Giacani et al. (2011):
- The authors investigated this TeV source of unknown classification by
using high-resolution radio images from archival ATCA and VLA data
combined with archival XMM-Newton X-ray data. Public data from the
SGPS, CfA CO and MIPSGAL surveys were used to investigate the ambient
interstellar medium in HI, 12CO and the mid infra red.
- "We investigate the physical properties of the supernova remnant
(SNR) G344.7−0.1, to clarify whether it hosts a pulsar wind nebula
(PWN), and the possible physical relationship between the SNR and the
gamma-ray source HESS J1702−420."
- "Based on the radio images and the comparison with X-ray and IR
observations, we confirm that there is no PWN within G344.7-0.1; the
observed emission highlights sites where the SN blast wave is
encountering dense material. No radio counterpart is found for the
X-ray object CXOU J170357.8-414302. The X-ray radiation completely
fills in the interior of the SNR, being thermal in nature and
originating in heated ejecta. From the spectral analysis it is
inferred that G344.7-0.1 is the result of a core-collapse SN that
exploded about 3000 yr ago. On the basis of HI absorption and emission
we redetermined its distance in (6.3 +/- 0.1) kpc. From the study of
the surrounding gas, we conclude that G344.7-0.1 has evolved within an
HI bubble created by the SN precursor. This bubble is, in turn, part
of a larger HI/IR ring created by the stellar wind of prior-generation
stars, about 2.6 x10e6 yr ago. A second generation of stars formed in
this compressed gas and about 3000 yr ago one of these stars exploded,
creating the SNR G344.7-0.1. This study suggests that G344.7-0.1 and
its turbulent environment is a plausible counterpart for HESS J1702−420."
Distance:
From
Giacani et al. (2011):
- the authors estimate a distance of 6.3 +/- 0.1 kpc in the case that
this TeV source is associated with the SNR G344.7-0.1
Seen by: H.E.S.S.
-
Constraining leptonic emission scenarios for the PeVatron candidate HESS J1702-420 with deep XMM-Newton observations
Giunti, L. et al., arXiv e-prints parXiv:2209.09566 (2022) [LINK]
-
Evidence of 100 TeV gamma-ray emission from HESS J1702-420: A new PeVatron candidate
Abdalla, H. et al., arXiv e-prints parXiv:2106.06405 (2021) [LINK]
-
Evidence of 100 TeV gamma-ray emission from HESS J1702-420: A new PeVatron candidate
Giunti, L. et al., arXiv e-prints parXiv:2108.02989 (2021) [LINK]
-
Status of Ground-based and Galactic Gamma-ray Astronomy
Mitchell, A.M.W., arXiv e-prints parXiv:2109.13753 (2021) [LINK]
-
Gamma-ray emission revealed at the western edge of SNR G344.7-0.1
Eagle, J. et al., arXiv e-prints parXiv:2006.08757 (2020) [LINK]
-
Probing the origin of the unidentified TeV \ensuremath\gamma-ray source HESS J1702-420 via the surrounding interstellar medium
Lau, J.C. et al., MNRAS 483 p3659-3672 (2019) [LINK]
-
A new study of the supernova remnant G344.7-0.1 located in the vicinity of the unidentified TeV source HESS J1702-420
Giacani, E. et al., A&A 531 pA138 (2011) [LINK]
-
HESS very-high-energy gamma-ray sources without identified counterparts
Aharonian, F. et al., A&A 477 p353-363 (2008) [LINK]
-
The H.E.S.S. Survey of the Inner Galaxy in Very High Energy Gamma Rays
Aharonian, F. et al., ApJ 636 p777-797 (2006) [LINK]
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