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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-41719

Ferreras, I; Saha, P; Leier, D; Courbin, F; Falco, E E (2010). Constraining the low-mass end of the initial mass function with gravitational lensing. Monthly Notices of the Royal Astronomical Society, 409(1):L30-L34.

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Abstract

The low-mass end of the stellar initial mass function (IMF) is constrained by focusing on the baryon-dominated central regions of strong lensing galaxies. We study in this Letter the Einstein Cross (Q2237+0305), a z = 0.04 barred galaxy whose bulge acts as lens on a background quasar. The positions of the four quasar images constrain the surface mass density on the lens plane, whereas the surface brightness (H-band HST/NICMOS imaging) along with deep spectroscopy of the lens (VLT/FORS1) allows us to constrain the stellar mass content, for a range of IMFs. We find that a classical single power law (Salpeter IMF) predicts more stellar mass than the observed lensing estimates. This result is confirmed at the 99 per cent confidence level, and is robust to systematic effects due to the choice of population synthesis models, the presence of dust or the complex disc/bulge population mix. Our non-parametric methodology is more robust than kinematic estimates, as we do not need to make any assumptions about the dynamical state of the galaxy or its decomposition into bulge and disc. Over a range of low-mass power-law slopes (with Salpeter being Γ = + 1.35) we find that at a 90 per cent confidence level, slopes Γ > 0 are ruled out.

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15 citations in Web of Science®
15 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
DDC:530 Physics
Language:English
Date:2010
Deposited On:02 Mar 2011 09:07
Last Modified:27 Nov 2013 20:22
Publisher:Wiley-Blackwell
ISSN:0035-8711
Additional Information:The definitive version is available at onlinelibrary.wiley.com
Publisher DOI:10.1111/j.1745-3933.2010.00941.x
Related URLs:http://arxiv.org/abs/1008.4363

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