14 research outputs found
Impact of the 3D source geometry on time-delay measurements of lensed type-Ia Supernovae
It has recently been proposed that gravitationally lensed type-Ia supernovae
can provide microlensing-free time-delay measurements provided that the
measurement is taken during the achromatic expansion phase of the explosion and
that color light curves are used rather than single-band light curves. If
verified, this would provide both precise and accurate time-delay measurements,
making lensed type-Ia supernovae a new golden standard for time-delay
cosmography. However, the 3D geometry of the expanding shell can introduce an
additional bias that has not yet been fully explored. In this work, we present
and discuss the impact of this effect on time-delay cosmography with lensed
supernovae and find that on average it leads to a bias of a few tenths of a day
for individual lensed systems. This is negligible in view of the cosmological
time delays predicted for typical lensed type-Ia supernovae but not for the
specific case of the recently discovered type-Ia supernova iPTF16geu, whose
time delays are expected to be smaller than a day.Comment: 7 pages, 4 figures, published in A&
IFC (incl. Editorial board)
We present a weak gravitational lensing measurement of the external
convergence along the line of sight to the quadruply lensed quasar
HE04351223. Using deep r-band images from Subaru-Suprime-Cam we observe
galaxies down to a 3 limiting magnitude of mags resulting in
a source galaxy density of 14 galaxies / arcmin after redshift-based cuts.
Using an inpainting technique and Multi-Scale Entropy filtering algorithm, we
find that the region in close proximity to the lens has an estimated external
convergence of and is hence marginally
under-dense. We also rule out the presence of any halo with a mass greater than
(68 confidence limit). Our
results, consistent with previous studies of this lens, confirm that the
intervening mass along the line of sight to HE04351223 does not affect
significantly the cosmological results inferred from the time delay
measurements of that specific object.Comment: 14 pages, 8 figures, 2 table
H0LiCOW XI. A weak lensing measurement of the external convergence in the field of the lensed quasar B1608+656 using HST and Subaru deep imaging
We investigate the environment and line of sight of the H0LiCOW lens
B1608+656 using Subaru Suprime-Cam and the Hubble Space Telescope (HST) to
perform a weak lensing analysis. We compare three different methods to
reconstruct the mass map of the field, i.e. the standard Kaiser-Squires
inversion coupled with inpainting and Gaussian or wavelet filtering, and
a method based on sparse regularization of the shear field. We
find no substantial difference between the 2D mass reconstructions, but we find
that the ground-based data is less sensitive to small-scale structures than the
space-based observations. Marginalising over the results obtained with all the
reconstruction techniques applied to the two available HST filters F606W and
F814W, we estimate the external convergence, at the position
of B1608+656 is , where the error bars
corresponds respectively to the 16th and 84th quartiles. This result is
compatible with previous estimates using the number-counts technique,
suggesting that B1608+656 resides in an over-dense line of sight, but with a
completely different technique. Using our mass reconstructions, we also compare
the convergence at the position of several groups of galaxies in the field of
B1608+656 with the mass measurements using various analytical mass profiles,
and find that the weak lensing results favor truncated halo models.Comment: Accepted MNRA
Stellar mass map and dark matter distribution in M31
Stellar mass distribution in M31 is estimated using optical and infrared
imaging data. Combining the derived stellar mass model with various kinematical
data, properties of the DM halo of the galaxy are constrained.
SDSS observations through the ugriz filters and the Spitzer imaging at 3.6
microns are used to sample the SED of the galaxy at each imaging pixel.
Intrinsic dust extinction effects are taken into account by using far-infrared
observations. Synthetic SEDs created with different stellar population
synthesis models are fitted to the observed SEDs, providing estimates for the
stellar mass surface density. The stellar mass distribution of the galaxy is
described with a 3D model consisting of a nucleus, a bulge, a disc, a young
disc and a halo component, each following the Einasto density distribution
(relations between different functional forms of the Einasto density
distribution are given in App. B). By comparing the stellar mass distribution
to the observed rotation curve and kinematics of outer globular clusters and
satellite galaxies, the DM halo parameters are estimated.
Stellar population synthesis models suggest that M31 is dominated by old
stars throughout the galaxy. The total stellar mass is (10-15)10^10Msun, 30% of
which is in the bulge and 56% in the disc. None of the tested DM distribution
models can be falsified on the basis of the stellar matter distribution and the
rotation curve of the galaxy. The virial mass of the DM halo is
(0.8-1.1)10^12Msun and the virial radius is 189-213kpc, depending on the DM
distribution. The central density of the DM halo is comparable to that of
nearby dwarf galaxies, low-surface-brightness galaxies and distant massive disc
galaxies, thus the evolution of central DM halo properties seems to be
regulated by similar processes for a broad range of halo masses, environments,
and cosmological epochs.Comment: 11 pages, 13 figures, 6 tables, accepted for publication in Astronomy
and Astrophysic
Stellar kinematics using a third integral of motion: method and application on the Andromeda galaxy
We probe the feasibility of describing the structure of a multicomponent axisymmetric galaxy with a dynamical model based on the Jeans equations while taking into account a third integral of motion. We demonstrate that using the third integral in the form derived by G. Kuzmin, it is possible to calculate the stellar kinematics of a galaxy from the Jeans equations by integrating the equations along certain characteristic curves. In the cases where the third integral ofmotion does not describe the system exactly, the derived kinematics would describe the galaxy only approximately. We apply our method to the Andromeda galaxy, for which the mass distribution is relatively firmly known. We are able to reproduce the observed stellar kinematics of the galaxy rather well. The calculated model suggests that the velocity dispersion ratios sigma(2)(z) /sigma(2)(R) of M31 decrease with increasing R. Moving away from the galactic plane, sigma(2)(z) /sigma(2)(R) remains the same. The velocity dispersions sigma(2)(theta) and sigma(2)(R) are roughly equal in the galactic plane
Stellar kinematics using a third integral of motion: method and application on the Andromeda galaxy
COSMOGRAIL XIX: Time delays in 18 strongly lensed quasars from 15 years of optical monitoring
International audienceWe present the results of 15 years of monitoring lensed quasars, which was conducted by the COSMOGRAIL programme at the Leonhard Euler 1.2 m Swiss Telescope. The decade-long light curves of 23 lensed systems are presented for the first time. We complement our data set with other monitoring data available in the literature to measure the time delays in 18 systems, among which nine reach a relative precision better than 15% for at least one time delay. To achieve this, we developed an automated version of the curve-shifting toolbox PyCS to ensure robust estimation of the time delay in the presence of microlensing, while accounting for the errors due to the imperfect representation of microlensing. We also re-analysed the previously published time delays of RX J1131−1231 and HE 0435−1223, by adding six and two new seasons of monitoring, respectively, and confirming the previous time-delay measurements. When the time delay measurement is possible, we corrected the light curves of the lensed images from their time delay and present the difference curves to highlight the microlensing signal contained in the data. To date, this is the largest sample of decade-long lens monitoring data, which is useful to measure H0 and the size of quasar accretion discs with microlensing as well as to study quasar variability.Key words: gravitational lensing: strong / cosmology: observations⋆ All light curves presented in this paper are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A10
VizieR Online Data Catalog: R-band light curves of 23 lensed QSOs (Millon+, 2020)
Data associated with paper Millon et al. 2020, A&A 639, A101. R-band cosmograil light curves of lensed quasars taken at the Euler 1.2m Swiss telescope with the EulerCAM and EulerC2 instrument. Additional data taken at the SMARTS 1.3m telescope with the ANDICAM optical/ infrared camera are also included for SDSS J0924+0219 (MacLeod et al., 2015ApJ...806..258M, Cat. J/ApJ/806/258). For HE 0435-1223 and RX J1131-1231, data taken at the 1.5m telescope at the Maidanak Observatory, the Mercator Belgian telescope and at the SMARTS 1.3 m telescope are included (Courbin et al. 2011A&A...536A..53C, Cat, J/A+A/536/A53, Tewes et al. 2013A&A...553A.120T, 2013A&A...556A..22T, Cat. J/A+A/556/A22). For SDSS J1515+1511, we had the data from Shalyapin & Goicoechea (2017ApJ...836...14S) from the Liverpool Telescope. (5 data files)
Citizens' juries in local government Report for the LGMB on the pilot projects
SIGLEAvailable from British Library Document Supply Centre-DSC:GPE/0856 / BLDSC - British Library Document Supply CentreGBUnited Kingdo