| Canonical Name: | Geminga |
| TeVCat Name: | TeV J0632+173 |
| Other Names: | 0FGL J0634.0+1745
MGRO C3
MGRO J0632+17
2HWC J0631+169
2HWC J0635+180
PSR J0633+1746 |
| Source Type: | PWN/TeV Halo |
| R.A.: | 06 32 28 (hh mm ss) |
| Dec.: | +17 22 00 (dd mm ss) |
| Gal Long: | 195.34 (deg) |
| Gal Lat: | 3.78 (deg) |
| Distance: | 0.25 kpc |
| Flux: | 0.23 (Crab Units) |
| Energy Threshold: | 3500 GeV |
| Spectral Index: | |
| Extended: | Yes |
| Size (X): | 2.60 (deg) |
| Size (Y): | 2.60 (deg) |
| Discovery Date: | 2009-04 |
| Discovered By: | Milagro |
| TeVCat SubCat: | Default Catalog |
Source Notes:
Source position and its uncertainty:
From Milagro
Abdo et al. (2009):
- R.A. (J2000): 06h 32m 28s
- Dec. (J2000): +17d 22'
- Uncertainty (from
Abdo et al., 2007): 0.4deg (stat); 0.3deg (syst)
From
Abeysekara et al.(2017):
Two 2HWC sources are associated with Geminga; their locations are:
2HWC J0631+169
- R.A. (J2000): 98.00
- Dec. (J2000): +17.00
- Statistical uncertainty: 0.11 deg
2HWC J0635+180
- R.A. (J2000): 98.83
- Dec. (J2000): +18.05
- Statistical uncertainty: 0.13 deg
Special Notes:
HAWC
Abeysekara et al.(2017):
- Energy range: hundreds of GeV to tens of TeV
- "2HWC J0631+169 and 2HWC J0635+180 are both found in the point
source search, each above the TS threshold value of 25. The
corresponding TS maximum in the 2-deg extended search is 126. They
appear to be associated with Geminga, a known GeV (
Abdo et al. 2010b)
gamma-ray pulsar. Prior to HAWC, Milagro was the only TeV instrument
to have detected it. Milagro reported an extended source of full width
at half maximum around 2.6 deg and a hard spectrum (
Abdo et al. 2009).
The large extent of the source makes it difficult for IACTs to observe
it. To date none have reported a detection of Geminga"
- 2HWC J0631+169 is located at 0.39 deg from Geminga
- 2HWC J0635+180 is located at 0.97 deg from Geminga
MAGIC
Ahnen et al. (2016):
- Energy range: 50 - 200 GeV
- The MAGIC Collaboration performed deep observations of Geminga,
which yielded 63 hours of good-quality data. They searched for
emission from the pulsar and pulsar wind nebula:
- "We did not find any significant detection, and derived 95%
confidence level upper limits. The resulting upper limits ... for the
Geminga pulsar and for the surrounding nebula at 50 GeV are the most
constraining ones obtained so far at VHE."
HAWC
Baughman et al.(2015):
- Energy range: HAWC's energy threshold is significantly lower than
Milagro's for these data
- HAWC’s preliminary results show an extended region of emission
consistent with that observed with Milagro.
- the authors note that "Imaging Atmospheric Cherenkov Telescopes
(IACTs) have observed Geminga without significant detection for over
two decades. An extended, hard TeV source is extremely difficult to
observe with the IACT technique. Milagro’s observation implies an
extended, hard spectrum source."
Milagro
Abdo et al. (2009):
- Energy: approx. 35 TeV
- Milagro report a source associated with 0FGL J0634.0+1745 with a
statistical significance of 3.5 sigma when the region around this
source is smoothed by the PSF of the Milagro detector. Since this
source seems to be extended however, the region is smoothed instead
with an additional 1 degree Gaussian to reveal the extension of the
source. This results in a significance of 6.3 sigma.
Source Location (J2000):
Milagro: ATel 2172
- R.A.: 06h 32m 28s
- Dec.: 17d 22m
Source Extent:
From
Mitchell et al. (2021):
- "H.E.S.S. confirms the detection of extended gamma-ray emission
around the Geminga pulsar in an independent dataset from that of the
previously announced detection"
- "we can state that the true radial extent of the emission is
definitely >= 2 deg and highly likely to be >= 3.2 deg. A forthcoming
publication will describe this analysis in detail, including the tests
made with different background approaches."
From
Mitchell & Caroff for the H.E.S.S. Collaboration (2019):
- an extension of >1 deg was reported for the region of the Geminga Pulsar
HAWC
Abeysekara et al.(2017):
- "When fitted with a uniform disk source model, the extent observed
in HAWC is around 2 deg in radius"
Milagro
Abdo et al. (2009):
- radius: 2.6 +0.7 -0.9 deg
Spectral Information:
HAWC
Abeysekara et al.(2017):
- the measured spectrum is relatively hard at 2.2
- the measured spectrum depends on the assumed morphology
Flux:
Milagro
Abdo et al. (2009):
- The flux quoted here is based on a comparison of the flux at 35 TeV
of 37.7e-17 /TeV /s /cm2 with that from the Crab (162.6e-17 /TeV /s /cm2)
also quoted at 35 TeV.
Distance:
From
Faherty et al. (2007):
- "We find the parallax pi = 4.0 +/- 1.3 mas, corresponding to a
distance to Geminga of (250 -62 +120) pc, a result 60% larger than the
previously published value. The proper motion is 178.2 +/- 1.8 mas/year."
Source Classification:
From
Di Mauro et al. (2019):
- "We detect a gamma-ray halo around Geminga with a significance in
the range 7.8-11.8 sigma depending on the interstellar emission model
considered. This measurement is compatible with e+ and e- emitted by
the PWN, which inverse-Compton scatter with photon fields located
within a distance of about 100 pc from the pulsar, where the diffusion
coefficient is estimated to be around 1.1 x 10e27 cm2/s at 100 GeV."
From
Abeysekara et al.(2017):
- "Compared to other TeV PWNe, the associated pulsar PSR J0633+1746 is
relatively old (342 kyr), nearby (250 +120 -62 pc) and has a low
spindown power (3.2 10e34 erg s-1 ). Geminga (together with PSR
B0656+14) has been proposed as the dominant source of the local
population of TeV electrons and positrons, and thus a possible
explanation for the PAMELA positron excess (
Aharonian et al. 1995;
Yuksel et al. 2009)."
From
Linden et al. (2017):
- the authors propose that this object is a member of a new class of
TeV emitters - "extrended TeV halos"
- "Observations by HAWC and Milagro have detected bright and spatially
extended TeV gamma-ray sources surrounding the Geminga and Monogem
pulsars. We argue that these observations, along with a substantial
population of other extended TeV sources coincident with pulsar wind
nebulae, constitute a new morphological class of spatially extended
TeV halos."
From
Acero et al. (2013):
- This LAT emission from this source below 10 GeV is likely from a
pulsar
Milagro
Abdo et al. (2009):
- This source is extended and associated with Geminga and is
therefore postulated to be the PWN of this pulsar
Emission components:
- no variability is reported by
Abdo et al. (2009) and, due to
its extent, the emission is assumed to arise from the nebula
- a pulsed component above 1 TeV has also been reported (4.4 sigma)
by
Neshpor et al. (2001); this has not been confirmed by other instruments
Seen by: Milagro, HAWC
-
Interpretation of the puzzling gamma-ray spectrum of the Geminga halo
Fang, Kun and Bi, Xiao-Jun, arXiv e-prints parXiv:2203.01546 (2022) [LINK]
-
Geminga contribution to the cosmic-ray positron excess according to the gamma-ray observations
Zhou, Guang-Yao et al., Communications in Theoretical Physics 74 p105403 (2022) [LINK]
-
The Physics of Pulsar Halos: Research Progress and Prospect
Liu, Ruo-Yu, arXiv e-prints parXiv:2207.04011 (2022) [LINK]
-
Are pulsar halos rare ?
Martin, Pierrick et al., arXiv e-prints parXiv:2206.11803 (2022) [LINK]
-
Self-generated cosmic-ray turbulence can explain the morphology of TeV halos
Mukhopadhyay, Payel and Linden, Tim, Phys. Rev. D 105 p123008 (2022) [LINK]
-
Gamma-ray haloes around pulsars as the key to understanding cosmic-ray transport in the Galaxy
López-Coto, Rubén et al., Nature Astronomy 6 p199-206 (2022) [LINK]
-
Geminga SNR: Possible candidate of local cosmic-ray factory
Zhao, Bing et al., arXiv e-prints parXiv:2104.07321 (2021) [LINK]
-
Does the Geminga gamma-ray halo imply slow diffusion around pulsars?
Recchia, Sarah et al., arXiv e-prints parXiv:2106.02275 (2021) [LINK]
-
Detection of extended TeV emission around the Geminga pulsar with H.E.S.S
Mitchell, A.M.W. et al., arXiv e-prints parXiv:2108.02556 (2021) [LINK]
-
Contribution of pulsars to cosmic-ray positrons in light of recent observation of inverse-Compton halos
Manconi, Silvia et al., Phys. Rev. D 102 p023015 (2020) [LINK]
-
Morphology of Gamma-Ray Halos around Middle-Aged Pulsars: Influence of the Pulsar Proper Motion
Zhang, Yi et al., arXiv e-prints parXiv:2010.15731 (2020) [LINK]
-
Cosmic-Ray Propagation in Light of Recent Observation of Geminga
Johannesson, G. et al., arXiv e-prints p (2019) [LINK]
-
Detection of a gamma-ray halo around Geminga with the Fermi-LAT and implications for the positron flux
Di Mauro, M. et al., arXiv e-prints p (2019) [LINK]
-
TeV Halos are Everywhere: Prospects for New Discoveries
Sudoh, T. et al., arXiv e-prints p (2019) [LINK]
-
Possible origin of the slow-diffusion region around Geminga
Kun, F. et al., arXiv e-prints p (2019) [LINK]
-
Prospects for the detection of synchrotron halos around middle-age pulsars
Di Mauro, M. et al., arXiv e-prints p (2019) [LINK]
-
Pulsars in a Bubble? Following Electron Diffusion in the Galaxy with TeV Gamma Rays
Fleischhack, H. et al., arXiv e-prints p (2019) [LINK]
-
Understanding the multiwavelength observation of Geminga's TeV halo: the role of anisotropic diffusion of particles
Liu, Ruo-Yu et al., arXiv e-prints parXiv:1904.11536 (2019) [LINK]
-
Constraining the Magnetic Field in the TeV Halo of Geminga with X-Ray Observations
Liu, Ruo-Yu et al., ApJ 875 p149 (2019) [LINK]
-
Search for very high energy (E > 100 GeV) Emission from Geminga supernova by VERITAS
Abeysekara, A., 36th International Cosmic Ray Conference (ICRC2019) 36 p616 (2019) [LINK]
-
Search for extended gamma-ray emission around the Geminga pulsar with H.E.S.S.
Mitchell, A. and Caroff, S. for the H.E.S.S. Collaboration, TeV Particle Astrophysics (2019) parXiv:2108.02556 (2019) [LINK]
-
Lessons from HAWC PWNe observations: the diffusion constant is not a
constant; Pulsars remain the likeliest sources of the anomalous positron
fraction; Cosmic rays are trapped for long periods of time in pockets
of inefficient diffusion
Profumo, S. et al., ArXiv e-prints p (2018) [LINK]
-
3D dynamics and morphology of bow-shock Pulsar Wind Nebulae
Barkov, M.V. and Lyutikov, M., ArXiv e-prints p (2018) [LINK]
-
Self-Generated Cosmic-Ray Confinement in TeV Halos: Implications for TeV Gamma-Ray Emission and the Positron Excess
Evoli, C. et al., ArXiv e-prints p (2018) [LINK]
-
Positron flux and gamma-ray emission from Geminga pulsar and pulsar wind nebula
Tang, X. and Piran, T., ArXiv e-prints p (2018) [LINK]
-
GeV observations of the extended pulsar wind nebulae challenge the pulsar interpretations of the cosmic-ray positron excess
Shao-Qiang et al., ArXiv e-prints p (2018) [LINK]
-
An undiscovered pulsar in the Local Bubble as an explanation of the local high energy cosmic ray electron spectrum
Lopez-Coto, R. et al., ArXiv e-prints p (2018) [LINK]
-
Using HAWC to Discover Invisible Pulsars
Linden, T. et al., ArXiv e-prints p (2017) [LINK]
-
TeV Gamma Rays From Galactic Center Pulsars
Hooper, D. et al., ArXiv e-prints p (2017) [LINK]
-
Constraining the Diffusion Coefficient with HAWC TeV Gamma-Ray Observations of Two Nearby Pulsar Wind Nebulae
Zhou, H. et al., ArXiv e-prints p (2017) [LINK]
-
Constraining the Origin of Local Positrons with HAWC TeV Gamma-Ray Observations of Two Nearby Pulsar Wind Nebulae
Salesa Greus, F. et al., ArXiv e-prints p (2017) [LINK]
-
Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
Abeysekara, A.U. et al., ArXiv e-prints p (2017) [LINK]
-
Constraining the properties of the magnetic turbulence in the Geminga region using HAWC gamma-ray data
Lopez-Coto, R. and Giacinti, G., ArXiv e-prints p (2017) [LINK]
-
Search for VHE gamma-ray emission from Geminga pulsar and nebula with the MAGIC telescopes
Ahnen, M.L. et al., ArXiv e-prints p (2016) [LINK]
-
First year results of the High Altitude Water Cherenkov observatory
Carraminana, A. and for the HAWC Collaboration, ArXiv e-prints p (2016) [LINK]
-
Geminga's puzzling pulsar wind nebula
Posselt, B. et al., ArXiv e-prints p (2016) [LINK]
-
VERITAS Observations of the Geminga Supernova Remnant
Andy Flinders for the VERITAS collaboration, ArXiv e-prints p (2015) [LINK]
-
TeV Gamma-Ray Emission Observed from Geminga with HAWC
Baughman, B.M. et al., ArXiv e-prints p (2015) [LINK]
-
Highlights from the High Altitude Water Cherenkov Observatory
Pretz, J. and for the HAWC Collaboration, ArXiv e-prints p (2015) [LINK]
-
Search for VHE gamma-ray emission from the Geminga pulsar and nebula with the MAGIC telescopes
Bonnefoy, S. for the MAGIC Collaboration, ICRC (2015) [LINK]
-
Constraints on the Galactic Population of TEV Pulsar Wind Nebulae Using Fermi Large Area Telescope Observations
Acero, F. et al., ArXiv e-prints p (2013) [LINK]
-
The gamma-ray spectrum of Geminga and the inverse Compton model of pulsar high energy emission
Lyutikov, M., ArXiv e-prints p (2012) [LINK]
-
New X-ray observations of the Geminga pulsar wind nebula
Pavlov, G.G. et al., ArXiv e-prints p (2010) [LINK]
-
Fermi LAT observations of the Geminga pulsar
Fermi-LAT Collaboration: A.A.~Abdo, ArXiv e-prints p (2010) [LINK]
-
Milagro Observations of Multi-TeV Emission from Galactic Sources in the Fermi Bright Source List
Abdo, A.A. et al., ApJ 700 pL127-L131 (2009) [LINK]
-
TeV Gamma Rays from Geminga and the Origin of the GeV Positron Excess
Yuksel, H. et al., Physical Review Letters 103 p051101-+ (2009) [LINK]
-
High-energy gamma-ray observations of Geminga with the Fermi Large Area Telescope
Razzano, M. et al., ArXiv e-prints p (2009) [LINK]
-
TeV Gamma-Ray Sources from a Survey of the Galactic Plane with Milagro
Abdo, A.A. et al., ApJ 664 pL91-L94 (2007) [LINK]
-
Ultrahigh-Energy Gamma-Ray Emission from the Geminga Pulsar
Neshpor, Y.I. et al., Astronomy Letters 27 p228-232 (2001) [LINK]
-
New Multi-TeV Gamma-Ray Sources MGRO J0632+17 and MGRO J2228+61
Goodman, J. & Sinnus, G., ATel 2172 [LINK]
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