| Canonical Name: | MAGIC J2001+435 |
| TeVCat Name: | TeV J2001+438 |
| Other Names: | 1FGL J2001.1+4351
MG4 J200112+4352 |
| Source Type: | IBL |
| R.A.: | 20 01 15.6 (hh mm ss) |
| Dec.: | +43 52 44.4 (dd mm ss) |
| Gal Long: | 79.07 (deg) |
| Gal Lat: | 7.10 (deg) |
| Distance: | z=0.1739 |
| Flux: | 0.09 (Crab Units) |
| Energy Threshold: | 200 GeV |
| Spectral Index: | 2.8 |
| Extended: | No |
| Discovery Date: | 2010-07 |
| Discovered By: | MAGIC |
| TeVCat SubCat: | Default Catalog |
Source Notes:
This source was moved from the "Newly Announced" to "Default" catalog (tardively) on 200106.
Detection:
Aleksic et al. (2014)
- "The object MAGIC J2001+439 was observed between 2009 November 7 and 26
for a total of 9.0 h. The MAGIC observations were also performed in
a MWL campaign between 2010 July 6 and September 8 for a total of 14.4 h.
The data were taken with zenith angles in the range 20 deg-40 deg in
2009 November and with zenith angles in the range 15 deg-30 deg during
the campaign in 2010 July-September."
- "We found an excess of events Nex = 125.0 +/- 20.2 in the energy
range above 70 GeV in the observation on 2010 July 16 in which the
effective observation time was 1.36 h"
- "This gamma-ray excess yields a signal significance of 6.3 sigma
calculated using Eq. (17) of
Li & Ma (1983). When correcting for the
seven observations (trials) performed in the MWL campaign, we find a
post-trial signal significance of 6.0 sigma, hence implying the first
detection of VHE gamma rays from 2FGL J2001.1+4352."
- "The source was not detected during the rest of the observing
campaign. In the data between 2010 July and September (excluding 2010
July 16), the significance of the excess in 8.0 h of observations is
1.1 sigma above the energy thresh- old of 70 GeV. Including the
observations from 2010 July 16, the significance (above 70 GeV) of the
accumulated dataset is 4 sigma. The data collected in 2009 November
led to 6.8 h of effective observation time, where we measure a
gamma-ray excess above the energy threshold of 100 GeV at a
significance level of 1.8 sigma."
Source position and its uncertainty:
On 200106 the source position was updated from that given in
Mariotti et al. (2010) to that in
Aleksic et al. (2014)
From
Aleksic et al. 2014:
R.A. (J2000): 20.021 +/- 0.001 h = 20h 01m 15.6s +/- 3.6s
Dec. (J2000): 43.879 +/- 0.010 deg = +43d 52' 44.4'' +/- 36''
From
Mariotti et al. 2010:
- R.A. (J2000): 20 01 13.5
- Dec. (J2000): 43 53 02.8
- no uncertainty on the source position is given
From
Berger et al. (2011):
- R.A. (J2000): 300.304 (=20h 01m 12.96s)
- Dec. (J2000): +43.886 (=+43d 53m 09.6s)
- no uncertainty on the source position is given
Source Association:
From
Aleksic et al. 2014:
- "The detected position of the excess
R.A. (J2000): 20.021 +/- 0.001 h,
Dec. (J2000): 43.879 +/- 0.010 deg
is consistent with the position of 2FGL J2001.1+43523 within 0.02 deg:
2FGL J2001.1+4352 is located at
R.A. (J2000): 20.019 h,
Dec. (J2000): 43.879 deg
in the 2FGL catalog (
Nolan et al. 2012)."
From
Mariotti et al. 2010:
- the source is associated with
1FGL J2001.1+4351,
which is located at R.A. 20 01 11.9, Dec. +43 51 51 (J2000)
- it is also associated with MG4 J200112+4352 (RA 20 01 12.9,
dec 43 52 52.8, J2000), which has been identified
as a BL Lac by
Bassani et al. (2009)
Flux:
From Aleksic et al. 2014:
- " The time-averaged integral photon flux above 200 GeV corresponds
to approx. 9% of the Crab Nebula flux. "
From Mariotti et al. 2010:
- ~20% of the Crab nebula flux above 100 GeV
From Berger et al. (2011):
- 22% of the Crab Nebula flux above 90 GeV
Spectral Properties:
From Aleksic et al. 2014:
The differential spectrum from the flare on 2010 July 16 can be described by a simple power law:
... dN/dE = F0 x (E/E0)^-A
... with flux normalization F0: 1.9 +/- 0.4 x10e-10 cm-2 s-1 TeV-1
... photon index A: 2.8 +/- 0.4
... E0: 200 GeV
The spectrum is fitted by a power-law function between 78 and 500 GeV.
The systematic uncertainties in the spectral measurements with MAGIC
stereo observations are 11% in the normalization factor (at 300 GeV)
and 0.15-0.20 in the photon index. The error on the flux does not
include uncertainty on the energy scale. The energy scale of the MAGIC
telescopes is determined with a precision of about 17% at low energies
(E < 100 GeV) and 15% at medium energies (E > 300 GeV).
Variability:
From Aleksic et al. 2014:
- "The multi-instrument observations show variability in all energy
bands with the highest amplitude of variability in the X-ray and VHE
bands. Besides the variability on few-day timescales, the long-term
monitoring of MAGIC J2001+439 shows that, the gamma-ray, optical, and
radio emissions gradually decreased on few-month timescales from 2010
through 2011, indicating that at least some of the radio, optical and
gamma-ray emission is produced in a single region by the same population
of particles."
From Berger et al. (2011):
- "MAGIC observed 1FGL J2001.1+4351 from July until September 2010. Only
one night, July 16th, showed a significant excess of 7.6 sigma (pre-trial)."
Classification:
Initially, this source was classified as a HBL in TeVCat. It was
updated (121113) to an IBL based on its classification in
the Fermi
2nd AGN Catalog (Ackermann et al. 2012). On 200106 it was re-classified
in TeVCat as a HBL based on the results of Aleksic et al. (2014).
From Aleksic et al. 2014:
- "We aim to characterize the broadband emission from 2FGL J2001.1+4352,
which has been associated with the unknown-redshift blazar MG4 J200112+4352.
Based on its gamma-ray spectral properties, it was identified as a
potential very high energy (VHE; E > 100 GeV) gamma-ray emitter."
- "The estimated synchrotron emission peak of MAGIC J2001+439 is
located at a high frequency ∼1016 Hz, which indicates that this
object is a typical HBL."
Distance:
From Goldoni et al. (2021):
- In this work, BL Lac objects, selected for their potential to be TeV
emitters detectable with CTA, were observed in the optical to
constrain or measure their redshifts.
- "We performed deep medium- to high-resolution spectroscopy of 19
blazar optical counterparts with the Keck II, SALT, and ESO NTT
telescopes. We searched systematically for spectral features and, when
possible, we estimated the contribution of the host galaxy to the
total flux."
- For MAGIC a redshift of z = 0.1739 +/- 0.0004 was measured
with a median signal to noise of 105 per spectral bin in the continuum
regions.
- The authors note: "In May 2018 the Tuorla blazar monitoring light
curve showed that MAGIC J2001+435 was in a low state with an observed
magnitude more than two magnitudes fainter than at the epoch of the
Keck/LRIS spectrum. It was decided, therefore, to observe it with
Keck/ESI in place of a previously scheduled target."
- "The exposure time was 3480 sec and the resulting S/N was 105. In
the final spectrum we estimate a redshift z=0.1739 +/- 0.0002 from the
detection of the CaHK, Mgb, CaFe, and possibly NaID absorption
features."
- "At a 4.6 sigma level we also detect the [NII]wavelength 6583
emission line at the same redshift. The result is consistent with the
imaging estimate in Aleksic et al. (2014) at less than 1 sigma. Our
redshift measurement was possible even though the S/N of our spectrum
is much lower than that from Shaw et al. (2013), demonstrating that
waiting for an optical low state may be very effective for blazar
redshift measurement."
From Aleksic et al. 2014:
- "We also determine for the first time the redshift of this BL Lac
object through the measurement of its host galaxy during low blazar
activity. Using the observational evidence that the luminosities of BL
Lac host galaxies are confined to a relatively narrow range, we obtain:
... z = 0.18 +/- 0.04.
Additionally, we use the Fermi-LAT and MAGIC gamma-ray spectra to
provide an independent redshift estimation:
... z = 0.17 +/- 0.10."
Seen by: MAGIC
-
Optical spectroscopy of blazars for the Cherenkov Telescope Array
Goldoni, P. et al., A&A 650 pA106 (2021) [LINK]
-
First broadband characterization and redshift determination of the VHE blazar MAGIC J2001+439
Aleksic, J. et al., A&A 572 pA121 (2014) [LINK]
-
Exploring the very high energy gamma-ray emission (E > 100 GeV) of the hard spectrum Fermi sources 1FGL J2001.1+4351 and B3-2247+381 with MAGIC
Berger, K. et al., ArXiv e-prints p (2011) [LINK]
-
On the identification of the Fermi/LAT source 0FGL J2001.0+4352 with a BL Lac
Bassani, L. et al., MNRAS 397 pL55-L59 (2009) [LINK]
-
Discovery of Very High Energy gamma-ray emission from 1FGL J2001.1+4351 by MAGIC
M. Mariotti on behalf of the MAGIC Collaboration, ATel 2753 [LINK]
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