Back to Main Page
Observation Date (UT) Observation Lat

Canonical Name:HESS J1844-030
TeVCat Name:TeV J1844-030
Other Names:SNR (PWN) G29.4+0.1
AX J1844.6-0305
PMN J1844-0306/GAL 29.39+0.10
2HWC J1844-032
Source Type:UNID
R.A.:18 44 41.22 (hh mm ss)
Dec.:-03 05 34.6 (dd mm ss)
Gal Long: 29.41 (deg)
Gal Lat: 0.09 (deg)
Distance:
Flux:0.01 (Crab Units)
Energy Threshold:200 GeV
Spectral Index:
Extended:No
Discovery Date:2015-07
Discovered By: H.E.S.S.
TeVCat SubCat:Newly Announced

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 J1844-030
Source Class: Unid
Identified Object: None
R.A. (J2000): 281.17 deg (18 44 41)
Dec. (J2000): -3.10 deg (-03 05 49)
Positional uncertainty: 0.023 deg
Spatial Model: Gaussian
Size: N/A
Spectral Model: power law
Integral Flux > 1 TeV: 2.76e-13 +/- 4.18e-14 cm-2 s-1
Pivot Energy, E0: 0.95 TeV
Diff. Flux at E0: 4.58e-13 +/- 5.64e-14 cm-2 s-1 TeV-1
Spectral Index: 2.48 +/- 0.12
HGPS Source Notes:
The following is the text from the HGPS paper:

An extended region of VHE emission, called HESS J1843-033, was first published by Hoppe (2008). This emission is resolved by the HGPS catalog analysis into three components that were merged into two distinct sources: HESS J1843-033 and HESS J1844-030.

HESS J1844-030 is a faint VHE gamma-ray source that compatible with being point-like and located in the vicinity of the complex region of HESS J1843-033. It is positionally coincident with a number of distinct objects, most notably the radio source PMN J1844-0306. The nature of the latter is ambiguous. Its elongated, jet-like morphology is very reminiscent of a radio galaxy, which is supported by 6 cm VLA observations revealing polarization along the structure (Helfand et al. 1989). This elongated radio feature is surrounded by a partial ring visible in the 21 cm VLA continuum image. The object is therefore classified as a SNR candidate in the MAGPIS catalog (Helfand et al. 2006), G29.37+0.10. It is also coincident with the X-ray source AX J1844.7-0305 (Vasisht et al. 2000; Sugizaki et al. 2001).

The association of the jet radio feature and the SNR candidate is unclear. Although rare, SNRs with jets are plausible, for example PWN structures such as MSH 15-52 (Gaensler et al. 2002) or the SS433/W 50 microquasar SNR system with its radio jets and lobes (Dubner et al. 1998; H.E.S.S. Collaboration 2018). The jet structure could also be a background radio galaxy aligned by chance with a faint radio shell. We note, however, thanks to H I absorption, Johanson & Kerton (2009) place the source at a distance between 5 and approx. 15 kpc. Interestingly, a heavily absorbed X-ray PWN, dubbed G29.4+0.1, is present in SNRcat and overlaps with a part of PMN J1844-0306. Further MWL observations will be necessary to assess the nature of the system and the origin of the VHE emission.

Two 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":
- PMN J1844-0306 (EXTRA)
- G29.4+0.1 (COMP)
"EXTRA associations: For completeness, in addition to the associations obtained through the catalog-based, automatic procedure, we add a list of 20 extra associated objects that are plausible counterparts for some HGPS sources and are not covered by the limited set of catalogs we use."

This detection was announced by C. Deil at the 34th ICRC.

Source position:
From Deil et al. (2015):
- Lat.: 29.41 deg
- Lon.: 0.09 deg
=> Convert this position to J2000 coordinates:
- R.A. (J2000): 18h 44m 41.22s
- Dec. (J2000): -03d 05' 34.6"
=> this is the position quoted in TeVCat
- no positional uncertainty is quoted

Source extent:
From Deil et al. (2015):
- an upper limit of 0.05 deg is placed on the extent

Flux:
From Deil et al. (2015):
- 1.0% Crab

Source Association:
From Cao et al. (2021):
- HESS J1844-030 may be associated with LHAASO J1843-0338
From Petriella (2019):
- the author investigates the possible connection between the SNR
(G29.37+0.1 - "the complex morphology of G29.37+0.1 in the radio band
could be caused by the superposition of two different sources, a
Galactic SNR and a radio galaxy"), the PWN (G29.4+0.1) and HESS
J1844-030:
-"HESS J1844-030 is a newly confirmed TeV source in the direction of
the X-ray pulsar wind nebula (PWN) candidate G29.4+0.1 and the complex
radio source G29.37+0.1, which is likely formed by the superposition
of a background radio galaxy and a Galactic supernova remnant (SNR).
Many scenarios have been proposed to explain the origin of HESS J1844-030,
based on several sources that are capable of producing very high
energy radiation. We investigate the possible connection between the
SNR, the PWN G29.4+0.1, and HESS J1844-030 to shed light on the
astrophysical origin of the TeV emission"
- "we conclude that G29.4+0.1 is a PWN and that a point source
embedded on it is the powering pulsar."
- "The HI data revealed that the SNR linked to G29.37+0.1 is a
Galactic source at 6.5 kpc and expanding in a nonuniform medium. From
the analysis of the pulsar motion and the pressure balance at the
boundary of X-ray emission, we conclude that G29.4+0.1 could be a PWN
that is located inside its host remnant, forming a new composite SNR."
- "Based on the magnetic field of the PWN obtained from the X-ray
luminosity, we found that the population of electrons producing
synchrotron radiation in the keV band can also produce IC photons in
the TeV band. This suggests that HESS J1844-030 could be the very high
energy counterpart of G29.4+0.1."
From Catelletti et al. (2017):
- "We report on the first detailed multiwavelength study of the radio
source G29.37+0.1, which is an as-yet-unclassified object linked to
the very-high-energy gamma-emitting source HESS J1844-030. The origin
of the multiwavelength emission toward G29.37+0.1 has not been
clarified so far, leaving open the question about the physical
relationship between these sources"
- the results of the high-sensitivity GMRT observations "lead us to
conclude that the brightest radio emission from G29.37+0.1 likely
represents a newly recognized radio galaxy. The identification of
optical and infrared counterparts to the emission arising from the
core of G29.37+0.1 strengthens our interpretation of an extragalactic
origin of the radio emission"
- "We performed several tests to explain the physical mechanism
responsible for the observed X-ray emission, which appears overlapping
the northeastern part of the radio emission. Our spectral analysis
demonstrated that a non-thermal origin for the X-ray emission
compatible with a pulsar wind nebula is quite possible. The analysis
of the spatial distribution of the CO gas revealed the presence of a
complex of molecular clouds located in projection adjacent to the
radio halo emission and probably interacting with it. We propose that
the faint halo represents a composite supernova remnant with a pulsar
powered component given by the diffuse X-ray emission superimposed
along the line of sight to the radio galaxy. Further broadband
observations of HESS J1844−030 are needed to disentangle its origin,
although its shape and position suggest an extragalactic origin
connected to G29.37+0.1."
From Abeysekara et al. (2017):
- this is one of three sources that could be associated with 2HWC J1844-032
From Deil et al. (2015):
- Several sources lie within the error contours or overlap with this source:
SNR (PWN) G29.4+0.1, AX J1844.6-0305 and PMN J1844-0306/GAL 29.39+0.10
- no further details are available in the PDF
- the source is classified as UNID in TeVCat for now


Seen by: H.E.S.S.
Want a reference added? Send a bibtex entry to the TeVCat Team