Back to Main Page
Observation Date (UT) Observation Lat

Canonical Name:LHAASO J0621+3755
TeVCat Name:TeV J0621+379
Other Names:3HWC J0621+382
PSR J0622+3749
1LHAASO J0622+3754
Source Type:PWN/TeV Halo
R.A.:06 21 52.8 (hh mm ss)
Dec.:+37 55 12 (dd mm ss)
Gal Long: 175.76 (deg)
Gal Lat: 10.95 (deg)
Distance:
Flux: (Crab Units)
Energy Threshold: GeV
Spectral Index:2.02
Extended:Yes
Size (X):0.40 (deg)
Size (Y):0.40 (deg)
Discovery Date:2021-06
Discovered By: LHAASO
TeVCat SubCat:Default Catalog

Source Notes:

Details of the source detection:

From Aharonian et al. (2021):
- "Here we report the detection of LHAASO J0621+3755, an extended
gamma-ray source with energies above 10 TeV, with half array of the
LHAASO experiment."
- "We report the discovery of an extended very-high-energy
gamma-ray source around the location of the middle-aged (207.8 kyr)
pulsar PSR J0622+3749 with the Large High Altitude Air Shower
Observatory (LHAASO).
- The source is detected with a significance of 8.2σ for E > 25 TeV
assuming a Gaussian template."

Source Position:

From Aharonian et al. (2021):
- R.A. (J2000): 95.47 deg +/- 0.11 deg = 06h 21m 52.8s +/- 26.4s
- Dec. (J2000): 37.92 deg +/- 0.09 deg = +37d 55m 12s +/- 324s

Source Extension:

From Aharonian et al. (2021):
- the extension is given as: 0.40 deg +/- 0.07 deg

Spectral Properties:

From Aharonian et al. (2021):
- The differential flux, assuming a power-law form of dN/dE = F0 x (E/E0)^-A is:
... F0: 3.11 +/- 0.38 (stat) +/- 0.22 (syst) x10e-16 TeV-1 cm-1 s-1
... E0: 40 TeV
... A: 2.92 +/- 0.17 (stat) +/- 0.02 (syst)
- "Above 100 TeV, we observed four photon-like events against 0.5
background events, which corresponds to a 3.1 sigma statistical
significance"

Distance:

From Aharonian et al. (2021):
- "LHAASO J0621+3755 is positionally coincident with the gamma-ray
pulsar J0622+3749 discovered by Fermi-LAT (Pletsch et al., 2012). The period of
PSR J0622+3749 is about 0.333s, the spin-down luminosity is 2.7 x 10e34 erg s−1,
and the characteristic age is about 207.8 kyr. No precise distance
measurement of the pulsar is available now. A “pseudo distance” of 1.6 kpc
was given via the correlation between the gamma-ray luminosity and the
spindown power for gamma-ray pulsars (Saz Parkinson et al., (2010)."

Possible Origin:

From Aharonian et al. (2021):
- "The centroid of LHAASO J0621+3755 is consistent with the location of
Fermi-LAT pulsar J0622+3749, with in an angular distance of 0.11 deg +/- 0.12 deg."
- "It is also consistent with the expectation of the pulsar halo model
that the gamma-ray emission above 10 TeV is close to the pulsar due to
the fast cooling of such VHE e+e-, even if there is a moderate proper
motion of the pulsar (Zhang et al., 2021)."
- "LHAASO J0621+3755 is a new source in the VHE domain"
- "It is potentially associated with 3HWC J0621+382 in the third HAWC
catalog (Albert et al. 2020), since the angular distance between
two sources is 0.31 deg +/- ± 0.32 deg."
- "In the GeV energy band, we find two 4FGL sources, 4FGL J0622.2+3749
and 4FGL J0620.3+3804 (Abdollahi et al., 2020), in the vicinity of
LHAASO J0621+3755. 4FGL J0620.3+3804 is associated with the radio source
GB6 J0620+3806 (Gregory et al., 1996), and is classified as a “bcu”
(blazar candidate of uncertain type) in the 4FGL catalog (Abdollahi et al., 2020)."
- "Since LHAASO J0621+3755 shows emission up to 100 TeV energies, we
expect that it should not be associated with 4FGL J0620.3+3804. The
other source, 4FGL J0622.2+3749, is a gamma-ray pulsar discovered
using the Fermi-LAT data (Pletsch et al., 2012). Multiwavelength
counterparts of the pulsar have been searched for in (Pletsch et al., 2012)."
- "No X-ray or pulsed radio emission has been found."


Seen by: LHAASO
Want a reference added? Send a bibtex entry to the TeVCat Team