Open AccessMicrolensing‐induced spectral variability in Q 2237+0305
Author(s) -
Geraint F. Lewis,
M. J. Irwin,
Paul C. Hewett,
C. B. Foltz
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01317.x
Subject(s) - gravitational microlensing , physics , quasar , astrophysics , photometry (optics) , lambda , spectral line , light curve , gravitational lens , emission spectrum , astronomy , line of sight , stars , galaxy , optics , redshift
We present both photometry and spectra of the individual images of the quadruple gravitational lens system Q 2237+0305. Comparison of spectra obtained at two epochs, separated by ∼3 yr, shows evidence for significant changes in the emission line‐to‐continuum ratio of the strong ultraviolet C IV λ1549, C III ] λ1909 and Mg II λ2798 lines. The short, ∼1 day, light‐travel time differences between the sight lines to the four individual quasar images rule out any explanation based on intrinsic variability of the source. The spectroscopic differences thus represent direct detection of microlensing‐induced spectroscopic differences in a quasar. The observations allow constraints to be placed on the relative spatial scales in the nucleus of the quasar, with the ultraviolet continuum arising in a region of ≲0.05 pc in extent, while the broad emission‐line material is distributed on scales much greater than this.