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Adaptive optics observations of the gravitationally lensed quasar SDSS J1405+0959
We present the result of Subaru Telescope multi-band adaptive optics
observations of the complex gravitationally lensed quasar SDSS J1405+0959,
which is produced by two lensing galaxies. These observations reveal
dramatically enhanced morphological detail, leading to the discovery of an
additional object 0. 26'' from the secondary lensing galaxy, as well as three
collinear clumps located in between the two lensing galaxies. The new object is
likely to be the third quasar image, although the possibility that it is a
galaxy cannot be entirely excluded. If confirmed via future observations, it
would be the first three image lensed quasar produced by two galaxy lenses. In
either case, we show based on gravitational lensing models and photometric
redshift that the collinear clumps represent merging images of a portion of the
quasar host galaxy, with a magnification factor of 15 - 20, depending on the
model.Comment: 12 pages, 8 figures, 7 tables. Submitted to MNRA
The Hubble Constant determined through an inverse distance ladder including quasar time delays and Type Ia supernovae
Context. The precise determination of the present-day expansion rate of the
Universe, expressed through the Hubble constant , is one of the most
pressing challenges in modern cosmology. Assuming flat CDM,
inference at high redshift using cosmic-microwave-background data from Planck
disagrees at the 4.4 level with measurements based on the local
distance ladder made up of parallaxes, Cepheids and Type Ia supernovae (SNe
Ia), often referred to as "Hubble tension". Independent,
cosmological-model-insensitive ways to infer are of critical importance.
Aims. We apply an inverse-distance-ladder approach, combining strong-lensing
time-delay-distance measurements with SN Ia data. By themselves, SNe Ia are
merely good relative distance indicators, but by anchoring them to strong
gravitational lenses one can obtain an measurement that is relatively
insensitive to other cosmological parameters. Methods. A cosmological parameter
estimate is performed for different cosmological background models, both for
strong-lensing data alone and for the combined lensing + SNe Ia data sets.
Results. The cosmological-model dependence of strong-lensing measurements
is significantly mitigated through the inverse distance ladder. In combination
with SN Ia data, the inferred consistently lies around 73-74 km s
Mpc, regardless of the assumed cosmological background model. Our
results agree nicely with those from the local distance ladder, but there is a
>2 tension with Planck results, and a ~1.5 discrepancy with
results from an inverse distance ladder including Planck, Baryon Acoustic
Oscillations and SNe Ia. Future strong-lensing distance measurements will
reduce the uncertainties in from our inverse distance ladder.Comment: 5 pages, 3 figures, A&A letters accepted versio
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