J/A+A/694/A206 OJ 287 polarisation in radio, mm and optical (Jormanainen+, 2025)
The polarisation behaviour of OJ 287 viewed through radio, millimetre and
optical observations between 2015 and 2017.
Jormanainen J., Hovatta T., Lindfors E., Berdyugin A., Chamani W.,
Fallah Ramazani V., Jermak H., Jorstad S.G., Laehteenmaeki A., McCall C.,
Nilsson K., Smith P., Steele I.A., Tammi J., Tornikoski M., Wierda F.
<Astron. Astrophys. 694, A206 (2025)>
=2025A&A...694A.206J 2025A&A...694A.206J (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; Polarization ; Optical ;
Radio sources ; Millimetric/submm sources
Keywords: galaxies: active - BL Lacertae objects: individual: OJ 287 -
galaxies: jets
Abstract:
OJ 287 is a bright blazar with century-long observations, and one of
the strongest candidates to host a supermassive black hole binary. Its
polarisation behaviour between 2015 and 2017 (MJD 57300-58000)
contains several interesting events that we re-contextualise in this
study. We collected optical photometric and polarimetric data from
several telescopes and obtained high-cadence light curves from this
period. In the radio band, we collected mm-wavelength polarisation
data from the AMAPOLA program. We combined these with existing
multifrequency polarimetric radio results and the results of
very-long-baseline-interferometry imaging with the Global mm-VLBI
Array at 86GHz. In December 2015, an optical flare was seen according
to the general relativistic binary black hole model. We suggest that
the overall activity near the accretion disk and the jet base during
this time may be connected to the onset of a new moving component K
seen in the jet in March 2017. With the additional optical data, we
find a fast polarisation angle rotation of ∼210° coinciding with
the December 2015 flare, hinting at a possible link between these
events. Based on the 86-GHz images, we calculated a new speed of
0.12mas/yr for K, which places it inside the core at the time of the
2015 flare. This speed also supports the scenario where the passage of
K through the quasi-stationary feature S1 could have been the trigger
for the very-high-energy gamma-ray flare of OJ 287 seen in February
2017. With the mm-polarisation data, we established that these bands
follow the cm-band data but show a difference during the time of K
passing through S1. This indicates that the mm-bands trace the
substructures of the jet still unresolved in the cm-bands.
Description:
Data points of Figs. 1 and 2.
In this work, we use some of the multiwavelength (MWL) total flux and
linear polarisation data from Myserlis et al. (2018A&A...619A..88M 2018A&A...619A..88M,
Cat. J/A+A/619/A88). These include the data from 2.64, 4.85, 8.35, and
10.45 GHzbands taken with the Effelsberg 100-m telescope as part of a
large multifrequency campaign (Komossa et al., 2015ATel.8411....1K 2015ATel.8411....1K)
started in December 2015 (MJD 57370).
To put the 2016 event described in Myserlis et al.
(2018A&A...619A..88M 2018A&A...619A..88M) in context in a more complete MWL picture, we
extended the period to span between October 5, 2015 and September 4,
2017 (MJD 57300-58000). We collected data from the well-sampled
Metsahovi blazar monitoring program at 37GHz from this entire period.
From the same extended period, we collected data from the ALMA
polarisation monitoring program AMAPOLA1 to bridge the gap between the
lower radio frequencies and the optical data. We added the data from
Bands 3 (97.5GHz) and 7 (343.4GHz), which had adequate sampling. The
AMAPOLA program is described in Kameno (2023, in ALMA at 10 years:
Past, Present, and Future, 38). For the ALMA bands, we removed those
polarisation degree (PD) and EVPA points whose corresponding
significance of the polarised flux density(PF) was less than 3σ.
For Band 3 the removed data was ∼15% of the data and for Band 7 ∼3%.
We show the evolution of flux density, PD, and EVPA in Fig. 1.
In the optical band, Myserlis et al. (2018A&A...619A..88M 2018A&A...619A..88M) used V-band
polarisation data of the Steward Observatory blazar monitoring
program2. As described in Sect. 2.1, we expanded the observation
period between MJD 57300-58000 and included more data from the the
Steward Observatory accordingly. We collected optical data from other
instruments to increase the sampling and especially to trace the EVPA
behaviour in detail. These include R-band photometry from the Steward
Observatory, R-band polarimetry and photometry data from the Boston
University Blazar monitoring3, g*-band polarimetry data from the
RINGO3 (Arnold et al., 2012, in Society of Photo-Optical
Instrumentation Engineers (SPIE) Conference Series, Vol. 8446,
Ground-based and Airborne Instrumentation for Astronomy IV, ed. I. S.
McLean, S. K. Ramsay, & H. Takami, 84462J) monitoring program, and V-
and R-band polarimetry data from DIPOL-2 polarimeter (Piirola et al.,
2014, in Society of Photo-Optical Instrumentation Engineers (SPIE)
Conference Series, Vol. 9147, Ground-based and Airborne
Instrumentation for Astronomy V, ed. S. K. Ramsay, I. S. McLean, & H.
Takami, 91478I). The Steward Observatory reduction process is
described in Smith et al. (2009, arXiv e-prints, 0912.3621 ),
the Boston University program in Jorstad & Marscher (2016, Galaxies,
4), and the RINGO3 program in McCall et al. (2024MNRAS.532.2788M 2024MNRAS.532.2788M). We
included R-band photometry and polarimetry data from the St.
Petersburg observatory in Russia, Crimean observatory, as well as from
the Kanata telescope in Hiroshima, Japan published in Gupta et al.
(2023ApJ...957L..11G 2023ApJ...957L..11G). Additionally, we included optical R-band
photometry data from the Tuorla blazar monitoring program4 (Takalo et
al., 2008, in American Institute of Physics Conference Series, Vol.
1085, American Institute of Physics Conference Series, ed. F. A.
Aharonian, W. Hofmann, & F. Rieger (AIP), 705-707), the analysis of
which is described in Nilsson et al. (2018A&A...620A.185N 2018A&A...620A.185N, Cat.
J/A+A/620/A185).
Because we combined the data from R- and V-bands as well as from the
g*-band (that is the closest equivalent to R-band from the three
RINGO3 bands, see McCall et al., 2024MNRAS.532.2788M 2024MNRAS.532.2788M), we
cross-checked the simultaneous values from these bands. The
differences in both PD and EVPA were small enough (EVPAs within 1-2
degrees) not to affect any of our conclusions.
The optical fluxes, PD and EVPA evolution are shown in Fig. 2.
Objects:
---------------------------------------------------
RA (2000) DE Designation(s)
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08 54 48.87 +20 06 30.6 OJ 287 = QSO J0854+2006
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1_1.dat 29 822 Flux densities in radio mm- and cm-bands
fig1_2.dat 41 543 Polarisation degrees in radio mm- and cm-bands
fig1_3.dat 32 543 Polarisation angles in radio mm- and cm-bands
fig2_1.dat 42 655 Flux densities in optical R-band
fig2_2.dat 40 981 Polarisation degrees in optical bands
fig2_3.dat 42 981 Polarisation angles in optical bands
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See also:
J/A+A/619/A88 : OJ287 high cadence polarization monitoring (Myserlis+, 2018)
J/A+A/620/A185 : Long-term optical monitoring of TeV Blazars (Nilsson+, 2018)
Byte-by-byte Description of file: fig1_1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 16 F6.3 Jy Flux Flux density
18- 22 F5.3 Jy e_Flux Error of flux density
24- 29 F6.2 GHz Freq Frequency (G1)
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Byte-by-byte Description of file: fig1_2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 16 F6.3 % PD Polarisation degree
18- 22 F5.3 % e_PD ? Error of PD, not for 97 and 343GHz PD
24- 28 F5.3 % b_PD ?=- Lower limit, only for 97 and 343GHz PD
30- 34 F5.3 % B_PD ?=- Upper limit, only for 97 and 343GHz PD
36- 41 F6.2 GHz Freq Frequency (G1)
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Byte-by-byte Description of file: fig1_3.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 18 F8.3 deg EVPA Electric vector polarisation angle
20- 25 F6.3 deg e_EVPA Error of EVPA
27- 32 F6.2 GHz Freq Frequency (G1)
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Byte-by-byte Description of file: fig2_1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 18 E8.2 Jy Flux Flux density in R-band
20- 27 E8.2 Jy e_Flux Error of flux density in R-band
29- 42 A14 --- Tel Telescope (1)
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Note (1): Telescopes are Crimea + St.Pt, Kanata, Perkins, SPOL or Tuorla.
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Byte-by-byte Description of file: fig2_2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 16 F6.3 % PD Polarisation degree
18- 22 F5.3 % e_PD Error of PD
24- 37 A14 --- Tel Telescope (G2)
39- 40 A2 --- Band Band (G2)
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Byte-by-byte Description of file: fig2_3.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d Time Observation time (MJD)
11- 18 F8.3 deg EVPA Electric vector polarisation angle
20- 24 F5.3 deg e_EVPA Error of EVPA
26- 39 A14 --- Tel Telescope (G2)
41- 42 A2 --- Band Band (G2)
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Global notes:
Note (G1): Frequencies are 2.64, 4.85, 8.35, 10.45, 37.00, 97.50 and 343.40GHz.
Note (G2): Telescops and bands are Crimea + St.Pt (R), Dipol (R), Dipol (V),
Kanata (R), Perkins (R), RINGO3 (g*) and SPOL (V).
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Acknowledgements:
J. Jormanainen, jesojo(at)utu.fi
(End) Patricia Vannier [CDS] 20-Jan-2025