Query : 2017A&A...604A..46B

2017A&A...604A..46B - Astronomy and Astrophysics, volume 604A, 46-46 (2017/8-1)

Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal.


Abstract (from CDS):

Context. Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses' dark matter content when combined with the study of the lenses' light profile. However, gravitational lensing galaxies, by definition, appear surrounded by lensed signal, both point-like and diffuse, that is irrelevant to the lens flux. Therefore, the observer is most often restricted to studying the innermost portions of the galaxy, where classical fitting methods show some instabilities.
Aims. We aim at subtracting that lensed signal and at characterising some lenses' light profile by computing their shape parameters (half-light radius, ellipticity, and position angle). Our objective is to evaluate the total integrated flux in an aperture the size of the Einstein ring in order to obtain a robust estimate of the quantity of ordinary (luminous) matter in each system.
Methods. We are expanding the work we started in a previous paper that consisted in subtracting point-like lensed images and in independently measuring each shape parameter. We improve it by designing a subtraction of the diffuse lensed signal, based only on one simple hypothesis of symmetry. We apply it to the cases where it proves to be necessary. This extra step improves our study of the shape parameters and we refine it even more by upgrading our half-light radius measurement method. We also calculate the impact of our specific image processing on the error bars.
Results. The diffuse lensed signal subtraction makes it possible to study a larger portion of relevant galactic flux, as the radius of the fitting region increases by on average 17%. We retrieve new half-light radii values that are on average 11% smaller than in our previous work, although the uncertainties overlap in most cases. This shows that not taking the diffuse lensed signal into account may lead to a significant overestimate of the half-light radius. We are also able to measure the flux within the Einstein radius and to compute secure error bars to all of our results.

Abstract Copyright: © ESO, 2017

Journal keyword(s): galaxies: elliptical and lenticular, cD - galaxies: luminosity function, mass function - gravitational lensing: strong - gravitational lensing: strong

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 4C 05.19 QSO 04 14 37.76734974 +05 34 42.3295956   24.100 23.800 21.270   ~ 349 2
2 [VV2006] J043814.8-122314 QSO 04 38 14.88 -12 17 14.6     17.15     ~ 211 2
3 QSO B0908+0603 QSO 09 11 27.6052 +05 50 54.281   18.44 18.16     ~ 222 2
4 QSO J0924+0219 QSO 09 24 55.8048 +02 19 24.850   18.58 18.36     ~ 127 1
5 QSO B1115+080A QSO 11 18 16.951 +07 45 58.23   16.61 16.44     ~ 667 2
6 QSO J1138+0314 QSO 11 38 03.7483141008 +03 14 57.657960780   19.42 19.17     ~ 58 1
7 QSO B1422+2309 BLL 14 24 38.09400 +22 56 00.5900   16.77 15.84 14.79   ~ 439 1

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