Back to Main Page
Observation Date (UT) Observation Lat

Canonical Name:HESS J1846-029
TeVCat Name:TeV J1846-029
Other Names:Kes75
SNR G29.70.3
1HWC J1844-031c
2HWC J1844-032
Source Type:PWN
R.A.:18 46 24 (hh mm ss)
Dec.:-02 58 26 (dd mm ss)
Gal Long: 29.71 (deg)
Gal Lat: -0.24 (deg)
Distance: 6.3 kpc
Flux:0.02 (Crab Units)
Energy Threshold: GeV
Spectral Index:2.26
Extended:No
Discovery Date:2007-10
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 J1846-029
Source Class: Composite
Identified Object: PSR J1846-0258
R.A. (J2000): 281.60 deg (18 46 24)
Dec. (J2000): -2.97 deg (-02 58 26)
Positional uncertainty: 0.015 deg
Spatial Model: Gaussian
Size: N/A
Spectral Model: power law
Integral Flux > 1 TeV: 4.76e-13 +/- 5.36e-14 cm-2 s-1
Pivot Energy, E0: 1.05 TeV
Diff. Flux at E0: 5.96e-13 +/- 5.59e-14 cm-2 s-1 TeV-1
Spectral Index: 2.41 +/- 0.09
HGPS Source Notes:
The following is the text from the HGPS paper:

VHE gamma-ray emission from the new source HESS J1846-029 is spatially coincident with G29.7-0.3 (also known as Kes 75), one of the youngest composite SNRs in the Galaxy, which contains the nebula of PSR J1846-0258. Preliminary results were presented in Djannati-Atai et al. (2008) and are compatible with those obtained in the HGPS analysis.

PSR J1846-0258 is a young, high magnetic-field pulsar. This source has a rotation period of 324 ms and a spin-down power of 8.3 × 10e36 erg s-1. It is among the youngest pulsars in the Galaxy with a characteristic age of only 723 yr (Livingstone et al. 2006). It has experienced a strong increase in its pulsed flux in June 2006 associated with spectral (Kumar & Safi-Harb 2008) and timing (Gavriil et al. 2008) changes in a similar manner to magnetars. The result of the search for variations in the VHE source flux at various timescales was negative (Terrier et al. 2008).

A nebula of 2000 in radius surrounds the pulsar in radio and X-ray wavelengths and Chandra high-resolution observations have revealed a jet and torus (Ng et al. 2008). A 30 diameter asymmetric radio shell surrounds the PSR and PWN system. It consists mainly of two lobes to the south of the pulsar. These lobes are emitting X-rays from heated swept-up interstellar matter and ejecta (Morton et al. 2007). Infrared measurements suggest that the shock is in a region of typical density of 60 cm-3 (Temim et al. 2012). Su et al. (2009) found a bubble in the molecular matter in good coincidence with the SNR. They proposed that this structure is the wind blown bubble of the SNR progenitor.

The extension of the VHE emission from HESS J1846-029 is compatible with that of a point-like source. The upper limit on the size is 0.03 deg, that is, comparable with the SNR shell size. The position of this object is compatible with the position of PSR J1846-0258, within localization uncertainties. Therefore, we are not able to distinguish between emission from the shell and emission from the PWN in this composite object.

Assuming a distance of 6 kpc (Leahy & Tian 2008), which yields a luminosity of L_gamma(1-10 TeV) = 6.9 × 10e33 (d/6 kpc)^2 erg s-1 , the apparent conversion efficiency of the rotational energy of the pulsar to gamma rays is ConvEff(1-10 TeV) ≡ L_gamma/Edot 0.08%. The VHE emission is therefore completely consistent with an origin in the PWN (see also, e.g., Tanaka & Takahara 2011; Torres et al. 2014). Yet, given the uncertainties on extension it is not possible to exclude a contribution from gamma rays produced by particles accelerated at the SNR shock, in particular from collisions of hadrons with ambient and swept-up matter at the shock, or even a contribution of escaping particles with the molecular shell revealed by Su et al. (2009).

This is one of the 31 firmly-identified objects among the HGPS sources. 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":
- J1846-0258 (PSR)
- G29.7-0.3 (COMP)

On 200320 this source was moved from the "Newly Announced" to the "Default" Catalogue.

Source position and its uncertainty:
On 200319 the source position was updated from that given in Djannati-Atai et al. (2008) to that
given in H.E.S.S. Collaboration (2018).
From H.E.S.S. Collaboration (2018):
- R.A. (J2000): 18h 46m 24s
- Dec. (J2000): -02d 58' 26''
- Positional uncertainty: 0.015 deg
From Djannati-Atai et al. (2008):
- R.A. (J2000): 18h 46m 24.1s +/- 0.5s
- Dec. (J2000): -02d 58' 53 +/- 34"

Distance:
From Leahy & Tian (2008):
- Kes 75 is likely at a distance of 5.1 to 7.5 kpc.
- The mean of these values, 6.3 kpc, is quoted here.

Spectral properties:
From Djannati-Atai et al. (2008):
- Spectral index: 2.26 +/- 0.15(stat)

Source Association:
From Gotthelf et al. (2020):
- "We model the dynamical and radiative evolution of the Kes 75 system
to estimate the birth properties of the neutron star, the energetics
of its progenitor, and properties of the PWN. This suggests that the
progenitor of Kes 75 was originally in a binary system which
transferred most its mass to a companion before exploding."

From Abeysekara et al. (2017):
- this is one of three sources that could be associated with 2HWC J1844-032
From Abeysekara et al. (2015):
- "1HWC J1844-031c has a post-trials significance of 4.7 sigma and is
spatially coincident with HESS J1843-033, which is classified as an
unidentified source. However, the morphology of this detection appears
to extend towards HESS J1846-029. Bartoli et al. (2013) reported a 4.2
sigma excess, ARGO J1841-0332, associated with HESS J1843-033 despite
being 0.7deg away, due to the large systematic pointing error at high
zenith angle."

Significance (provided here for sources Newly Announced Catalog):
From Djannati-Atai et al. (2008)
- 8.3 sigma

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