Publication:
Microlensing of Quasars by Stars in Their Damped Lyα Absorbers

No Thumbnail Available

Date

1997

Published Version

Journal Title

Journal ISSN

Volume Title

Publisher

American Astronomical Society
The Harvard community has made this article openly available. Please share how this access benefits you.

Research Projects

Organizational Units

Journal Issue

Citation

Perna, Rosalba, and Abraham Loeb. 1997. “Microlensing of Quasars by Stars in Their Damped Lyα Absorbers.” The Astrophysical Journal 489 (2): 489–500. https://doi.org/10.1086/304806.

Research Data

Abstract

The damped Ly alpha absorbers (DLAs) in quasar spectra are believed to be the progenitors of present-day disk galaxies. We examine the probability for microlensing of background quasars by stars in their DLAs. Microlensing by an individual star should magnify the continuum but not the broad emission lines of the quasars. Consequently, the equivalent width distribution of microlensed quasars would be distorted. We model a representative spiral galaxy as a closed system composed of a bulge, a disk, and a halo, and we evolve the mass fraction of stars in the disk based on the observed metallicity of DLAs at high redshifts. The microlensing signatures are stronger if the halo of the galaxy is made of massive compact halo objects (MACHOs). In this case, the distortion imprinted by microlensing on the equivalent width distribution of quasar emission lines can be detected with high significance in a sample of similar to 10 DLAs with H I column densities N greater than or similar to 10(21) cm(-2) and absorption redshifts z(abs) less than or similar to 1. About one-tenth of all quasars with DLAs (N greater than or similar to 10(20) cm(-2)) might show excess variability on timescales shorter than 5 yr. A search for these signals would complement microlensing searches in local galaxies and calibrate the MACHO mass fraction in galactic halos at high redshifts.

Description

Other Available Sources

Keywords

Terms of Use

This article is made available under the terms and conditions applicable to Other Posted Material (LAA), as set forth at Terms of Service

Endorsement

Review

Supplemented By

Referenced By

Related Stories