J/A+A/710/A15 LTI-GRAVITY observations of Ton 599 (Hovatta+, 2026)
VLTI-GRAVITY observations of blazars.
Hovatta T., Lindfors E., Korhonen H., Kharb P., Wittkowski M., Labdon A.,
Pursimo T., Wiik K.
<Astron. Astrophys. 710, A15 (2026)>
=2026A&A...710A..15H 2026A&A...710A..15H (SIMBAD/NED BibCode)
ADC_Keywords: Polarization ; QSOs ; Optical
Keywords: galaxies: active - galaxies: jets - quasars: individual: Ton 599
Abstract:
Parsec-scale jets of blazars have so far been spatially resolved only
in millimeter and submillimeter wavelengths, where very long baseline
interferometry can be used to obtain milliarcsecond-scale images of
the jets. We have attempted to spatially resolve the near-infrared
emission in jet-dominated blazars for the first time. We used the
VLTI-GRAVITY instrument to obtain milliarcsecond-scale near-infrared
interferometric observations of a flaring blazar Ton 599.
Additionally, we observed four non-flaring blazars using the
GRAVITY-wide mode, where a nearby bright star is used as a fringe
tracker. We modeled the squared visibilities of Ton 599 and found that
they are incompatible with a single unresolved point source unless
there is a significant amount of additional unknown coherence loss in
the instrument. With the present data, we cannot distinguish between a
model with an unresolved point source and extended emission or
coherence loss and a model with a single Gaussian component. This
suggests that we are seeing the unresolved or only partially resolved
jet-base in near-infrared wavelengths. The wide-field mode of GRAVITY
was challenging for the additional relatively faint targets, resulting
in either non-detections or poor-quality data that could not be
modeled. Our observations demonstrate that it is possible to detect
the compact jet emission in blazars with near-infrared interferometry,
suggesting that with the improved GRAVITY+ instrument it will be
possible to spatially resolve and image the near-infrared emission of
blazar jets.
Description:
Calibrated squared visibilities as a function of baseline length for
Ton 599. The baseline length is given in units of megalambda i.e.
million times the wavelength of the observation.
Objects:
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RA (2000) DE Designation(s)
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11 59 31.83 +29 14 43.8 Ton 599 = 1RXS J115931.4+291446
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
vis2.dat 15 59 Squared visibilities (Fig. 2)
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See also:
J/A+A/703/A259 : Multiband optical variability of blazar Ton 599 (Vince+, 2025)
Byte-by-byte Description of file: vis2.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 --- Mlambda Baseline length
7- 10 F4.2 --- V2 Visibility squared, V2
12- 15 F4.2 --- e_V2 1-sigma uncertainty of V2
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Acknowledgements:
Talvikki Hovatta, talvikki.hovatta(at)aalto.fi
License: CC-BY-4.0
(End) Talvikki Hovatta [Aalto U., Finland], Patricia Vannier [CDS] 05-May-2026