We present a strong lensing system, composed of four multiple images of a source at z = 2.387, created by two lens galaxies, G1 and G2, belonging to the galaxy cluster MACS J1115.9+0129 at z = 0.353. We use observations taken as part of the Cluster Lensing and Supernova survey with Hubble, and its spectroscopic follow-up programme at the Very Large Telescope, to estimate the total mass distributions of the two galaxies and the cluster through strong gravitational lensing models. We find that the total projected mass values within the half-light radii, R<SUB>e</SUB>, of the two lens galaxies are M<SUB>T,G1</SUB>(<R<SUB>e, G1</SUB>) = (3.6 ± 0.4) × 10<SUP>10</SUP>M<SUB>☉</SUB>and M<SUB>T,G2</SUB>(<R<SUB>e, G2</SUB>) = (4.2 ± 1.6) × 10<SUP>10</SUP>M<SUB>☉</SUB>. The effective velocity dispersion values of G1 and G2 are (122 ± 7) km s<SUP>-1</SUP>and (137 ± 27) km s<SUP>-1</SUP>, respectively. We remark that these values are relatively low when compared to those of ≈200-300 km s<SUP>-1</SUP>, typical of lens galaxies found in the field by previous surveys. By fitting the spectral energy distributions of G1 and G2, we measure projected luminous over total mass fractions within R<SUB>e</SUB>of 0.11 ± 0.03, for G1, and 0.73 ± 0.32, for G2. The fact that the less massive galaxy, G1, is dark matter-dominated in its inner regions raises the question of whether the dark matter fraction in the core of early-type galaxies depends on their mass. Further investigating strong lensing systems will help us understand the influence that dark matter has on the structure and evolution of the inner regions of galaxies.

Dark matter fraction of low-mass cluster members probed by galaxy-scale strong lensing

MERCURIO, AMATA;
2016-01-01

Abstract

We present a strong lensing system, composed of four multiple images of a source at z = 2.387, created by two lens galaxies, G1 and G2, belonging to the galaxy cluster MACS J1115.9+0129 at z = 0.353. We use observations taken as part of the Cluster Lensing and Supernova survey with Hubble, and its spectroscopic follow-up programme at the Very Large Telescope, to estimate the total mass distributions of the two galaxies and the cluster through strong gravitational lensing models. We find that the total projected mass values within the half-light radii, Re, of the two lens galaxies are MT,G1(e, G1) = (3.6 ± 0.4) × 1010Mand MT,G2(e, G2) = (4.2 ± 1.6) × 1010M. The effective velocity dispersion values of G1 and G2 are (122 ± 7) km s-1and (137 ± 27) km s-1, respectively. We remark that these values are relatively low when compared to those of ≈200-300 km s-1, typical of lens galaxies found in the field by previous surveys. By fitting the spectral energy distributions of G1 and G2, we measure projected luminous over total mass fractions within Reof 0.11 ± 0.03, for G1, and 0.73 ± 0.32, for G2. The fact that the less massive galaxy, G1, is dark matter-dominated in its inner regions raises the question of whether the dark matter fraction in the core of early-type galaxies depends on their mass. Further investigating strong lensing systems will help us understand the influence that dark matter has on the structure and evolution of the inner regions of galaxies.
2016
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4814892
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 8
  • ???jsp.display-item.citation.isi??? 8
social impact