J/A+A/641/L2 ALMA third image of lensed quasar PKS 1830-211 (Muller+, 2020)
All good things come in threes: the third image of the lensed quasar
PKS 1830-211.
Muller S., Jaswanth S.. Horellou C., Marti-Vidal I.
<Astron. Astrophys. 641, L2 (2020)>
=2020A&A...641L...2M 2020A&A...641L...2M (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Gravitational lensing ; Radio sources
Keywords: gravitational lensing: strong - quasars: individual: PKS 1830-211
Abstract:
Strong gravitational lensing distorts our view of sources at
cosmological distances but brings invaluable constraints on the mass
content of foreground objects and on the geometry and properties of
the Universe. We report the detection of a third continuum source
toward the strongly lensed quasar PKS 1830-211 in ALMA
multi-frequency observations of high dynamic range and high angular
resolution. This third source is point-like and located slightly to
the north of the diagonal joining the two main lensed images, A and B,
0.3" away from image B. It has a flux density that is 140 times
weaker than images A and B and a similar spectral index, compatible
with synchrotron emission. We conclude that this source is most likely
the expected highly de-magnified third lensed image of the quasar. In
addition, we detect, for the first time at millimeter wavelengths,
weak and asymmetrical extensions departing from images A and B that
correspond to the brightest regions of the Einstein ring seen at
centimeter wavelengths. Their spectral index is steeper than that of
compact images A, B, and C, which suggests that they arise from a
different component of the quasar. Using the GravLens code, we explore
the implications of our findings on the lensing model and propose a
simple model that accurately reproduces our ALMA data and previous VLA
observations. With a more precise and accurate measurement of the time
delay between images A and B, the system PKS 1830-211 could help to
constrain the Hubble constant to a precision of a few percent.
Description:
ALMA observations of PKS 1830-211 were carried out on 2019 July 10
and 11 in bands 4 (∼150GHz) and 6 (∼230GHz), and on 2019 July 28 in
bands 5 (∼180GHz) and 7 (∼280GHz).
Images (FITS format) of the quasar PKS1830-211, obtained with ALMA in
band 4, 5, 6, and 7, as presented in the Figure 1 of the paper.
Objects:
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RA (2000) DE Designation(s)
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18 33 39.92 -21 03 39.9 PKS 1830-211 = QSO B1830-211
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 123 4 List of fits images
fits/* . 4 Individual fits images
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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- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 55 A26 "datime" Obs.date Observation date
57- 63 F7.3 GHz Freq Observed frequency
65- 69 I5 Kibyte size Size of FITS file
71- 86 A16 --- FileName Name of FITS file, in subdirectory fits
88-123 A36 --- Title Title of the FITS file
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Acknowledgements:
Sebastien Muller, sebastien.muller(at)chalmers.se
(End) Patricia Vannier [CDS] 26-Aug-2020