| Canonical Name: | SNR G015.4+00.1 |
| TeVCat Name: | TeV J1818-154 |
| Other Names: | HESS J1818-154
2HWC J1819-150* |
| Source Type: | Composite SNR |
| R.A.: | 18 18 04.8 (hh mm ss) |
| Dec.: | -15 28 01 (dd mm ss) |
| Gal Long: | 15.41 (deg) |
| Gal Lat: | 0.16 (deg) |
| Distance: | 4.8 kpc |
| Flux: | 0.018 (Crab Units) |
| Energy Threshold: | 1000 GeV |
| Spectral Index: | 2.1 |
| Extended: | No |
| Discovery Date: | 2011-12 |
| 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 J1818-154 |
| Source Class: | PWN |
| Identified Object: | G015.4+00.1 |
| R.A. (J2000): | 274.52 deg (18 18 04) |
| Dec. (J2000): | -15.47 deg (-15 28 10) |
| Positional uncertainty: | 0.023 deg |
| Spatial Model: | Gaussian |
| Size: | N/A |
| Spectral Model: | power law |
| Integral Flux > 1 TeV: | 2.31e-13 +/- 4.58e-14 cm-2 s-1 |
| Pivot Energy, E0: | 1.54 TeV |
| Diff. Flux at E0: | 1.07e-13 +/- 2.02e-14 cm-2 s-1 TeV-1 |
| Spectral Index: | 2.21 +/- 0.15 |
| HGPS Source Notes: | |
| | |
This is one of the 31 firmly-identified objects among the HGPS sources. One possible association is 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":
- G15.4+0.1 (COMP)
Source Classification:
131028: Updated classification from PWN to Composite SNR.
From
H.E.S.S. Collaboration (2013):
- "Together, the X-ray and VHE gamma-ray emission provide strong
evidence for the existence of a PWN located inside the shell of
G15.4+0.1 and this SNR can therefore be classified as a composite based
on these observations."
From
Castelletti et al. (2013):
- The 13CO observations clearly show a molecular cloud about 5' in
size with two bright clumps, labeled A and B, clump A positionally
associated with the location of HESS J1818-154 and clump B in
coincidence with the brightest northern border of the radio SNR
shell. The HI absorption and the 13CO emission study indicates a
possible interaction between the molecular material and the
remnant. ... Calculations show that the average density of the
molecular clump A is sufficient to produce the detected gamma-ray
flux, thus favoring a hadronic origin for the high-energy emission.
From
Hofverberg et al. (2011):
- "The question is then whether the VHE emission originates from the
shell of the SNR or from a putative PWN embedded inside the
SNR. However, since the extension of the H.E.S.S. source is
significantly smaller than the extension of the SNR as seen in the
archival VLA data, it is clear that the bulk of the VHE emission
originates from a yet unknown source located within the shell. The
discovery of a radio or X-ray PWN counterpart to HESS J1818−154 would
confirm this scenario."
Source Location:
The source position was updated on 131028.
From
H.E.S.S. Collaboration (2013):
- R.A. (J2000): 18h 18m 04.8s +/- 3.1s(stat)
- Dec. (J2000): -15d 28' 01" +/- 43"(stat)
- Systematic uncertainty: 20"
From
Hofverberg et al. (2011):
- R.A. (J2000): 18 18 03.4 +/- 4.6s(stat) +/- 20"(syst)
- Dec. (J2000): -15 27 54 +/- 68"(stat) +/- 20"(syst)
Distance:
130925: Updated to distance from
Castelletti et al. (2013)
From
Su et al. (2017):
Using data from the Southern Galactic Plane Survey (SGPS) and the
HI/OH/Recombination line survey (THOR) the authors place the following
constraints on the distance to G15.4+0.1 which is likely associated
with TeV source HESS J1818-154:
- lower limit distance of about 8.0 kpc
- upper limit distance of about 10.5 kpc.
"The new distance revises parameters on its associated pulsar wind
nebula and TeV source."
From
Castelletti et al. (2013):
- "On the basis of HI absorption features, we estimate the distance to
G15.4+0.1 in 4.8 ± 1.0 kpc."
From
Hofverberg et al. (2011):
- "Little is known about the distance and age of G 15.4+0.1. Using the
uncertain Sigma-D relationship, a distance of 10 +/- 3 kpc is derived."
Spectral Properties:
From
H.E.S.S. Collaboration (2013):
- Spectral index: 2.3 +/- 0.3(stat) +/- 0.2(syst)
From
Hofverberg et al. (2011):
- Spectral index: 2.1 +/- 0.3(stat) +/- 0.2(syst)
Source Extent:
131028: Updated morphology from extended to point source.
From
H.E.S.S. Collaboration (2013):
- "The morphology of the TeV emission is compatible with originating
from a point-like source. The 99% confidence upper limit on the
Gaussian width of the source is 0.072deg."
From
Hofverberg et al. (2011):
- 8.5' +/- 1.8' (stat) (= 0.14deg +/- 0.03 deg)
Source Association:
From
Abeysekara et al. (2017):
- "
2HWC J1819-150* is 0.5 deg away from the nearest source listed in
TeVCat, SNR G015.4+00.1 (HESS J1818-154). This source is reported by
H.E.S.S. as a point source, which given the distance to the HAWC
location makes the association uncertain."
- it is marked with an asterisk in the 2HWC catalog because it is not
separated from its neighbour by a large TS gap (details in the paper
referenced above)
Seen by: H.E.S.S., HAWC
-
The H.E.S.S. Galactic plane survey
H.E.S.S. Collaboration et al., A&A 612 pA1 (2018) [LINK]
-
The revised distance of supernova remnant G15.4+0.1
Su, H. et al., ArXiv e-prints p (2017) [LINK]
-
The 2HWC HAWC Observatory Gamma-Ray Catalog
Abeysekara, A.U. et al., ApJ 843 p40 (2017) [LINK]
-
A hadronic scenario for HESS J1818-154
Castelletti, G. et al., A&A 557 pL15 (2013) [LINK]
-
HESS J1818-154, a new composite supernova remnant discovered in TeV gamma rays and X-rays
H.E.S.S. Collaboration, ArXiv e-prints p (2013) [LINK]
-
Discovery of VHE gamma-ray emission from the SNR G15.4+0.1 with H.E.S.S
Hofverberg, P. et al., ArXiv e-prints p (2011) [LINK]
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