Kavli Affiliate: Robert A. Simcoe
| First 5 Authors: Anna-Christina Eilers, Anna-Christina Eilers, , ,
| Summary:
Ultra-violet (UV) radiation from accreting black holes ionizes the
intergalactic gas around early quasars, carving out highly ionized bubbles in
their surroundings. Any changes in a quasar’s luminosity are therefore
predicted to produce outward-propagating ionization gradients, affecting the
Lyman-$alpha$ (Ly$alpha$) absorption opacity near the quasar’s systemic
redshift. This "proximity effect" is well-documented in rest-UV quasar spectra
but only provides a one-dimensional probe along our line-of-sight. Here we
present deep spectroscopic observations with the James Webb Space Telescope
(JWST) of galaxies in the background of a super-luminous quasar at $z_rm
QSOapprox6.3$, which reveal the quasar’s "light echo" with Ly$alpha$
tomography in the transverse direction. This transverse proximity effect is
detected for the first time towards multiple galaxy sightlines, allowing us to
map the extent and geometry of the quasar’s ionization cone. We obtain
constraints on the orientation and inclination of the cone, as well as an upper
limit on the obscured solid angle fraction of $f_rm obsc<91%$.
Additionally, we find a timescale of the quasar’s UV radiation of $t_rm
QSO=10^5.6^+0.1_-0.3$ years, which is significantly shorter than would
be required to build up the central supermassive black hole (SMBH) with
conventional growth models, but is consistent with independent measurements of
the quasars’ duty cycle. Our inferred obscured fraction disfavors a scenario
where short quasar lifetimes can be explained exclusively by geometric
obscuration, and instead supports the idea that radiatively inefficient
accretion or growth in initially heavily enshrouded cocoons plays a pivotal
role in early SMBH growth. Our results pave the way for novel studies of
quasars’ ionizing geometries and radiative histories at early cosmic times.
| Search Query: ArXiv Query: search_query=au:”Robert A. Simcoe”&id_list=&start=0&max_results=3