J/A+A/695/L1 VLTI/GRAVITY limit on Gaia BH3 emission (Kervella+, 2025)
VLTI/GRAVITY upper limit on near-infrared emission from the nearby 33 M☉
black hole Gaia BH3.
Kervella P., Panuzzo P., Gallenne A., Merand A., Arenou F., Caffau E.,
Lacour S., Mazeh T., Holl B., Babusiaux C., Nardetto N., Clavel M.,
Le Bouquin J.-B., Segransan D.
<Astron. Astrophys. 695, L1 (2025)>
=2025A&A...695L...1K 2025A&A...695L...1K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, population II ; Interferometry
Keywords: techniques: interferometric - binaries: general - stars: black holes -
stars: individual: LS II +14 13 - stars: Population II
Abstract:
The recent astrometric discovery of the nearby (590pc), massive
(33M☉) dormant black hole candidate Gaia BH3 offers the
possibility to resolve angularly the black hole from its companion
star using optical interferometry. We aim at detecting emission in the
near-infrared K band from the close-in environment of Gaia BH3 caused
by accretion. Gaia BH3 (LS II +14 13) has been observed using the
GRAVITY instrument with the four 8-m Unit Telescopes of the VLT
Interferometer. We searched for the signature of emission of Gaia BH3
in the interferometric observables using the CANDID, PMOIRED and
exoGravity tools. With a separation of 18mas, the Gaia BH3 system is
well resolvable angularly by GRAVITY. We did not detect emission from
the black hole at a contrast level of Δm=6.8mag with respect to
the companion star, that is, fBH/fstar<0.2%. This corresponds to
an upper limit on the continuum flux density of
fBH<1.9*10-16W/m2/micron in the K band. We also did not detect
emission from the black hole in the hydrogen BrGamma line. The
non-detection of near-infrared emission from the black hole in Gaia
BH3 indicates that its accretion of the giant star wind is presently
occurring at most at a very low rate. This is consistent with the
limit of fEdd<4.9*10-7 derived previously on the Eddington ratio
for an advection-dominated accretion flow. Deeper observations with
GRAVITY may be able to detect the black hole as the companion star
approaches periastron around year 2030.
Description:
The provided OIFITS2 data files contain the GRAVITY reduced and calibrated
interferometric data obtained on Gaia BH3. The OIFITS2 data format is
described in Duvert, Young & Hummel (2017A&A...597A...8D 2017A&A...597A...8D).
Objects:
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RA (2000) DE Designation(s)
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19 39 18.71 +14 55 54.0 Gaia BH3 = Gaia DR3 4318465066420528000
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 140 13 List of Gaia BH3 OIFITS2 data files
fits/* . 13 Individual Gaia BH3 OIFITS2 data files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 42 A23 "datime" Obs.date Observation date
44- 48 F5.3 Mbyte size Size of FITS file
50- 83 A34 --- FileName Name of FITS file, in subdirectory fits
85-140 A56 --- Title Title of the FITS file
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Acknowledgements:
Pierre Kervella, pierre.kervella(at)obspm.fr
References:
Duvert G., Young J. & Hummel C.A., 2017A&A...597A...8D 2017A&A...597A...8D
https://doi.org/10.1051/0004-6361/201526405
OIFITS 2: the 2nd version of the data exchange standard for optical
interferometry
(End) Pierre Kervella [Obs. de Paris], Patricia Vannier [CDS] 10-Feb-2025