J/A+A/706/A283 MeerKAT L-band map of V4641 Sgr (Grollimund+, 2026)
Large-scale radio bubbles around the black hole transient V4641 Sgr.
Grollimund N., Corbel S., Fender R., Matthews J.H., Heywood I.,
Cowie F.J., Hughes A.K., Carotenuto F., Motta S.E., Woudt P.
<Astron. Astrophys. vol, page (2026)>
<Astron. Astrophys. 706, A283 (2026)>
=2026A&A...706A.283G 2026A&A...706A.283G (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray ; Radio continuum ; Black holes
Keywords: accretion, accretion disks - black hole physics -
relativistic processes - ISM: jets and outflows - X-rays: binaries
Abstract:
Black holes (BHs) in microquasars can launch powerful relativistic
jets that have the capacity to travel up to several parsecs from the
compact object and interact with the interstellar medium. Recently,
the detection of large-scale very-high-energy (VHE) gamma-ray emission
around the black hole transient V4641 Sgr and other BH-jet systems
suggested that jets from microquasars may play an important role in
the production of galactic cosmic rays.
V4641 Sgr is known for its superluminal radio jet discovered in 1999,
but no radio counterpart of a large-scale jet has been observed. The
goal of this work is to search for a radio counterpart of the extended
VHE source.
We observed V4641 Sgr with the MeerKAT radio telescope at the L and
UHF bands and produced deep maps of the field using high dynamic range
techniques.
We report the discovery of a large-scale (35pc), bow-tie-shaped,
diffuse, radio structure around V4641 Sgr, with similar angular size
to the extended X-ray emission discovered by XRISM. However, it is not
spatially coincident with the extended VHE emission. After discussing
the association of the structure with V4641 Sgr, we investigate the
nature of the emission mechanism. We suggest that the bow-tie
structure arose from the long-term action of large-scale jets or disk
winds from V4641 Sgr. If the emission mechanism is of synchrotron
origin, the radio/X-ray extended structure implies acceleration of
electrons up to more than 100TeV as far as tens of parsecs from the
black hole.
Description:
MeerKAT L-band map of the V4641 Sgr field at 8 arcsecond resolution.
Total exposure time of ∼11hrs.
Objects:
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RA (2000) DE Designation(s)
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18 19 21.63 -25 24 25.8 V4641 Sgr = 2CXO J181921.6-252425
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
obs.dat 150 1 SARAO MeerKAT L-band intensity map properties
list.dat 88 1 Description of fits image
fits/* . 1 Individual fits image of V4641 Sgr
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Byte-by-byte Description of file: obs.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Object name (target_name)
10- 26 F17.13 deg RAdeg Right ascension (ICRS) at Ep=2000 (s_ra)
28- 45 F18.14 deg DEdeg Declination (ICRS) at Ep=2000 (s_dec)
47- 64 F18.16 deg FOV Field of view (s_fov)
66- 72 A7 --- Region Pixel region (s_region) (1)
74- 76 F3.1 arcsec Res Angular pixel resolution (s_region)
78- 94 F17.11 s tmin Minimum time (t_min)
96-103 F8.2 s tmax Maximum time (t_max)
105-109 I5 s Exp Exposure time (t_exptime)
111 I1 arcsec tRes Time resolution (t_resolution)
113-131 F19.17 Jy/beam Imin Minimum intensity at 856 MHz (em_min)
133-150 F18.16 Jy/beam Imax Maximum intensity at 1578 MHz (em_max)
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Note (1): Polygon ICRS values points are :
276.59555150873274 -26.957353424704174,
273.08504139267893 -26.957357442643314,
273.129977025901 -23.828648533993725,
276.55060710026277 -23.828644618896.
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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- 5 I5 --- Nx Number of pixels along X-axis
7- 11 I5 --- Ny Number of pixels along Y-axis
13- 18 I6 Kibyte size Size of FITS file
20- 32 A13 --- FileName Name of FITS file, in subdirectory fits
34- 88 A55 --- Title Title of the FITS file
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Acknowledgements:
Noa Grollimund, noa.grollimund(at)cea.fr
(End) Noa Grollimund [CEA Saclay], Luc Trabelsi [CDS] 06-Jan-2026