Direct evidence of non-disk optical continuum emission around an active black hole

Doron Chelouche, Francisco Pozo Nuñez, Shai Kaspi

Research output: Contribution to journalLetterpeer-review


Accretion onto black holes is key to their growth over cosmic time 1 , especially during the active galactic nuclei phase when the inflowing material forms a radiatively efficient accretion disk 2 . To probe the disk, indirect imaging methods such as reverberation mapping 3–6 and microlensing 7,8 are required. Recent findings suggest that the disk may be larger than theoretical predictions by a factor of a few 4,6,9 , thus casting doubt on our understanding of accretion in the general astrophysical context. Whether new physics is implied 10–12 or poorly understood biases are in effect 5,6,13,14 is a longstanding question. Here, we report new reverberation data based on a unique narrowband-imaging design 15 , and argue that time delays between adjacent optical bands are primarily associated with the reprocessing of light by a farther away under-appreciated non-disk component. This component is associated with high-density photoionized material that is uplifted from the outer accretion disk, probably by radiation-pressure force on dust, and thus may represent the long-sought origin of the broad-line region 16 . Our findings suggest that the optical phenomenology of some active galactic nuclei may be substantially affected by non-disk continuum emission with implications for measuring the fundamental properties of black holes and their active environs over cosmic time.

Original languageEnglish
Pages (from-to)251-257
Number of pages7
JournalNature Astronomy
Issue number3
StatePublished - 1 Mar 2019

Bibliographical note

Publisher Copyright:
© 2018, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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