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Observation Date (UT) Observation Lat

Canonical Name:LHAASO J2226+6057
TeVCat Name:TeV J2227+609
Other Names:VER J2227+608
Boomerang Nebula
SNR G106.3+2.7
PSR J2229+6114
Source Type:UNID
R.A.:22 27 00 (hh mm ss)
Dec.:+60 57 00 (dd mm ss)
Gal Long: 106.28 (deg)
Gal Lat: 2.84 (deg)
Distance:
Flux:1.05 (Crab Units)
Energy Threshold:100000 GeV
Spectral Index:3.01
Extended:Yes
Size (X):0.00 (deg)
Size (Y):0.00 (deg)
Discovery Date:2021-05
Discovered By: LHAASO
TeVCat SubCat:Default Catalog

Source Notes:

Details of the source detection:

From Cao et al. (2021):
- "At 100 TeV, the angular and energy resolutions are about 15–20 arcmin
and better than 20%, respectively, allowing adequate spectroscopic and
morphological studies."
- "The statistical significance of the detection above 100 TeV is calculated
using a 0.3deg extension template"
- "Crab Units (CU), flux of the Crab Nebula at 100 TeV; 1 CU = 6.1 x 10-17 photons TeV-1 cm-2 s-1)"
- Significance above 100 TeV: 13.6 sigma
- E_max (PeV): 0.57 +/- 0.19
- Differential photon flux at 100 TeV (CU): 1.05 +/- 0.16
- On-source events/Off-source events: 60/6.2
- Exposure (hr): 2401.3

Source Position:

From Cao et al. (2021):
- R.A. (J2000): 336.75 = 22h 27m 00s
- Dec. (J2000): +60.95 = +60d 57m

Spectral Properties:

From Cao et al. (2021):
- "For the three most significantly detected sources, LHAASO J1825-1326,
LHAASO J1908+0621 and LHAASO J2226+6057, we determine their SEDs."
- The authors show "the spectral energy distributions of three
luminous sources with fluxes exceeding 1 CU (at 100 TeV): LHAASO
J1825-1326, LHAASO J1908+0621 and LHAASO J2226+6057. Above 100 TeV,
the spectra of these sources are steep, characterized by a power-law
photon index of approx. 3. However, a closer look reveals that
between 10 TeV and 500 TeV, the spectra experience gradual
steepening with energy. To explore this tendency, the spectra were
fitted by the so-called log-parabola function dN/dE ∝ E-A(E), where
the local photon index A(E) = a + blogE (a and b are free
parameters) characterizes the slope of the tangent. For all three
spectra, the log-parabola fits are preferred over simple power-law
fits. The gradual steepening of multi-hundred-teraelectronvolt gamma
rays is partly due to the photon-photon absorption that occurs
during their interactions with the diffuse far-infrared and
microwave radiation fields."
- For LHAASO J2226+6057 the parameters of the fit are:
... a: 1.56
... b: 0.88
... A: 3.01

Possible Origin:

From Cao et al. (2021):
- This list contains sources potentially at the origin of the LHAASO source, together with their class, their distance, age and luminosity
- SNR G106.3+2.7, Supernova Renmant, Distance: 0.8 kpc, Age: approx. 10 kyr
- PSR J2229+6614, Pulsar, Distance: 0.8 kpc, Age: approx. 10 kyr, L_s: 2.2 x10e37

Potential TeV Counterparts:
From Cao et al. (2021):
- This list contains "Nearby teraelectronvolt sources within 1deg of the centre of the LHAASO source"
- VER J2227+608
- Boomerang Nebula

Details of the source detection:

From Cao et al. (2021):
- "At 100 TeV, the angular and energy resolutions are about 15–20 arcmin
and better than 20%, respectively, allowing adequate spectroscopic and
morphological studies."
- "The statistical significance of the detection above 100 TeV is calculated
using a 0.3deg extension template"
- "Crab Units (CU), flux of the Crab Nebula at 100 TeV; 1 CU = 6.1 x 10-17 photons TeV-1 cm-2 s-1)"
- Significance above 100 TeV: 8.3 sigma
- E_max (PeV): 0.43 +/- 0.05
- Differential photon flux at 100 TeV (CU): 0.38 +/-0.09
- On-source events/Off-source events: 30/6.4
- Exposure (hr): 2525.8

Source Position:

From Cao et al. (2021):
- R.A. (J2000): 317.15 = 21h 08m 36s
- Dec. (J2000): +51.95 = +51d 57m 00s

Possible Origin:

From Cao et al. (2021):
- No source is identified as a possible origin.

Potential TeV Counterparts:

From Cao et al. (2021):
- There are no nearby TeV sources (i.e. within 1 deg of the centre of the LHAASO source).

Pevatron:

From Mitchell (2021):
- this source is included in a list of Galactic sources currently known
to produce gamma-ray emission above 100 TeV.



Seen by: LHAASO
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