Measurement of the broad-line region size in a luminous macho quasar

Doron Chelouche, Eliran Daniel, Shai Kaspi

Research output: Contribution to journalArticlepeer-review


We measure the broad emission line region (BLR) size of a luminous, L 1047 erg s-1, high-z quasar using broadband photometric reverberation mapping. To this end, we analyze 7.5 years of photometric data for MACHO13.6805.324 (z ≃ 1.72) in the B and R MACHO bands and find a time delay of 180 ± 40days in the rest frame of the object. Given the spectral-variability properties of high-z quasars, we associate this lag with the rest-UV iron emission blends. Our findings are consistent with a simple extrapolation of the BLR size-luminosity relation in local active galactic nuclei to the more luminous, high-z quasar population. Long-term spectroscopic monitoring of MACHO13.6805.324 may be able to directly measure the line-to-continuum time delay and test our findings.

Original languageEnglish
Article numberL43
JournalAstrophysical Journal Letters
Issue number2
StatePublished - 10 May 2012


  • galaxies: active
  • methods: data analysis
  • quasars: emission lines
  • quasars: individual (MACHO 13.6805.324)
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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