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Observation Date (UT) Observation Lat

Canonical Name:PSR J2032+4127
TeVCat Name:TeV J2032+414
Other Names:MT91 213
Source Type:Binary
R.A.:20 32 10 (hh mm ss)
Dec.:+41 27 34 (dd mm ss)
Gal Long: 80.22 (deg)
Gal Lat: 1.04 (deg)
Distance: 1.8 kpc
Flux: (Crab Units)
Energy Threshold: GeV
Spectral Index:
Extended:No
Discovery Date:2017-10
Discovered By: VERITAS
TeVCat SubCat:Default Catalog

Source Notes:

PSR J2032+4127 is co-located with the extended TeV gamma-ray source, TeV J2032+4130, and may be physically associated with it.

Source Information:
From VERITAS and MAGIC Collaborations (2018):
- "We report on observations of the pulsar / Be star binary system
PSR J2032+4127 / MT91 213 in the energy range between 100 GeV and 20 TeV
with the VERITAS and MAGIC imaging atmospheric Cherenkov telescope
arrays. The binary orbit has a period of approximately 50 years, with
the most recent periastron occurring on 2017 November 13."
- "A new, point-like, gamma-ray source is detected, coincident with the
location of PSR J2032+4127 / MT91 213."
- "This result adds a new member to the small population of known TeV
binaries, and it identifies only the second source of this class in
which the nature and properties of the compact object are firmly
established."

Binary Period:
From Ho et al. (2017):
- "Our extended orbital phase coverage in radio, supplemented with
Fermi LAT gamma-ray data, allows us to update and refine the orbital
period to 45-50 yr and time of periastron passage to 2017 November."

Pulsar and Massive Companion Information:
From VERITAS and MAGIC Collaborations (2018):
- "Pulsed emission, with a period of P = 143 ms, was first detected
from PSR J2032+4127 in a blind search of Fermi-LAT gamma-ray data
(Abdo et al. 2009) and was subsequently detected in radio observations
with the Green Bank Telescope (Camilo et al. 2009)."
- "These observations revealed dramatic changes in the pulsar spindown
rate, an effect most easily explained by Doppler shift due to the
pulsar’s motion in a long-period binary system (Lyne et al. 2015)."
- "The pulsar’s companion was identified as a B0Ve star, MT91 213,
which has a mass of around 15 M_solar and a circumstellar disk which
varies in radius by more than a factor of two, from 0.2 AU to 0.5 AU
(Ho et al. 2017)."
- "The pulsar spin-down luminosity is 1.7 x10e35 erg s−1, with a
characteristic age of 180 kyr, and the system lies at a distance of
1.4 - 1.7 kpc, in the Cyg OB2 stellar association."
- "Further observations refined the orbital parameters, yielding a
binary period of 45–50 years, an eccentricity between 0.94 and 0.99,
and a longitude of periastron between 21 deg and 52 deg."
- "Periastron occurred on 2017 November 13 with a separation between
PSR J2032+4127 and MT91 213 of approximately 1 AU (Ho et al. 2017;
Coe et al. 2017)"

Source position and its uncertainty:
On 181016, the position reported here was updated from that reported
by The VERITAS and MAGIC Collaborations (2017) to that reported
in VERITAS and MAGIC Collaborations (2018).

From VERITAS and MAGIC Collaborations (2018):
VERITAS:
- R.A. (J2000): 20h 32m 10s +/- 2s (stat) 2s (syst)
- Dec. (J2000): 41d 27' 34'' +/- 16'' (stat) 26'' (syst)
MAGIC:
- R.A. (J2000): 20h 32m 07s +/- 2s (stat)
- Dec. (J2000): 41d 28' 04'' +/- 20'' (stat)

From The VERITAS and MAGIC Collaborations (2017):
- R.A. (J2000): 20h 32m 13.13s
- Dec. (J2000): +41d 27' 24.4''

Source Notes:
From The VERITAS and MAGIC Collaborations (2017):
- "The MAGIC and VERITAS collaborations report a continuing increase
in TeV gamma-ray emission from the 50-year period pulsar/ Be-star
binary system PSR J2032+4127/ MT91 213."
- "The system reached periastron on 13 November 2017. The Swift X-ray
flux has dropped dramatically over the past two weeks (see ATEL #10920
and the Swift light curve)."
"TeV emission associated with the binary was first reported in ATEL #10810,
covering observations up to late September 2017. The TeV flux has
further increased since then. Preliminary analysis of the most recent
observations gives integral fluxes above 200 GeV of 1.9e-11 +/-
0.4e-11 photons cm^-2 s^-1 for an observation of 1.9 hours on Nov 12
(MJD 58069.8) with MAGIC. This implies an increase in the flux of
almost a factor 10 with respect to the average flux in
June-August. The flux measured by VERITAS is also enhanced, at the
level of 1.3e-11 +/- 0.2e-11 photons cm^-2 s^-1 for 4 hours of
observations between Nov 10 and Nov 13."

From The VERITAS and MAGIC Collaborations (2017):
The VERITAS and MAGIC collaborations are carrying out observations on
this source as part of a coordinated long-term monitoring campaign.
- "The VERITAS and MAGIC collaborations report the detection of an
enhanced TeV gamma-ray flux from the pulsar/ Be-star binary system PSR
J2032+4127/ MT91 213."
- The VERITAS flux corresponds to approximately twice the flux
measured at the same location in archival VERITAS observations from
spring 2017
- The MAGIC flux implies an increase by about a factor of 2 with
respect to the mean flux observed by MAGIC in June-August 2017.

From Ho et al. (2017):
- "The radio and gamma-ray pulsar PSR J2032+4127 was recently found to
be in a decades-long orbit with the Be star MT91 213, with the pulsar
moving rapidly towards periastron. This binary shares many similar
characteristics with the previously unique binary system PSR
B1259-63/LS 2883. Here, we describe radio, X-ray, and optical
monitoring of PSR J2032+4127/MT91 213. Our extended orbital phase
coverage in radio, supplemented with Fermi LAT gamma-ray data, allows
us to update and refine the orbital period to 45-50 yr and time of
periastron passage to 2017 November. "

From Lyne et al. (2015):
- "PSR J2032+4127 is a gamma-ray and radio-emitting pulsar which has
been regarded as a young luminous isolated neutron star. However, its
recent spin-down rate has extraordinarily increased by a factor of 2.
We present evidence that this is due to its motion as a member of a
highly-eccentric binary system with an ˜15-M⊙ Be star, MT91 213.
Timing observations show that, not only are the positions of the two
stars coincident within 0.4 arcsec, but timing models of binary motion
of the pulsar fit the data much better than a model of a young isolated
pulsar. MT91 213, and hence the pulsar, lie in the Cyg OB2 stellar
association, which is at a distance of only 1.4-1.7 kpc. The pulsar is
currently on the near side of, and accelerating towards, the Be star,
with an orbital period of 20-30 yr. The next periastron is well
constrained to occur in early 2018, providing an opportunity to
observe enhanced high-energy emission as seen in other Be-star binary
systems."

Spectral and flux information:
From VERITAS and MAGIC Collaborations (2018):
- A complete listing of the spectral parameters can be found in Table 1
of VERITAS and MAGIC Collaborations (2018).
- " The flux is variable over at least an order of magnitude, peaking
at periastron."
- "Two models were tested for the binary emission: a pure power law
and a power law with an exponential cutoff. The VERITAS data favor the
cutoff model over the power law for the binary emission, with an
F-test probability of 0.997 and a cutoff energy of 0.57 +/- 0.20 TeV.
MAGIC observations also favor an exponential cutoff, with a
probability of 0.993 and a cutoff energy of 1.40 +/- 0.97 TeV."
- " We performed a global fit to the datasets, with the high and low
states fit with the baseline power law plus either a pure power law or
a power-law with an exponential cutoff."
- "The VERITAS data favor a cutoff model in the low state, with an
F-test probability of 0.999 and a cutoff value of 0.33 +/- 0.13
TeV. MAGIC observations also favor a low-state cutoff model, with a
probability of 0.980 and a cutoff value of 0.58 ± 0.33 TeV."
- "For both observatories, the high-state data are well-fit by a pure
power law and including a cutoff does not significantly change the
quality of the fit."

Distance:
From VERITAS and MAGIC Collaborations (2018):
- "The pulsar spin-down luminosity is 1.7 x10e35 erg s−1, with a
characteristic age of 180 kyr, and the system lies at a distance of
1.4 - 1.7 kpc, in the Cyg OB2 stellar association."

From Camilo et al. (2009):
- A distance of approximately 1.8 kpc is proposed.

Seen by: MAGIC
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