Abstract
Supermassive black holes in galaxy centres can grow by the accretion of
gas, liberating energy that might regulate star formation on galaxy-wide
scales. The nature of the gaseous fuel reservoirs that power black hole
growth is nevertheless largely unconstrained by observations, and is
instead routinely simplified as a smooth, spherical inflow of very hot
gas. Recent theory and simulations instead predict that accretion can be
dominated by a stochastic, clumpy distribution of very cold molecular
clouds—a departure from the ‘hot mode’ accretion
model—although unambiguous observational support for this
prediction remains elusive. Here we report observations that reveal a
cold, clumpy accretion flow towards a supermassive black hole fuel
reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy
(BCG), a nearby (redshift z = 0.0821) giant elliptical
galaxy surrounded by a dense halo of hot plasma. Under the right
conditions, thermal instabilities produce a rain of cold clouds that
fall towards the galaxy’s centre, sustaining star formation amid a
kiloparsec-scale molecular nebula that is found at its core. The
observations show that these cold clouds also fuel black hole accretion,
revealing ‘shadows’ cast by the molecular clouds as they
move inward at about 300 kilometres per second towards the active
supermassive black hole, which serves as a bright backlight.
Corroborating evidence from prior observations of warmer atomic gas at
extremely high spatial resolution, along with simple arguments based on
geometry and probability, indicate that these clouds are within the
innermost hundred parsecs of the black hole, and falling closer towards
it.
Original language | English |
---|---|
Pages (from-to) | 218-221 |
Number of pages | 4 |
Journal | Nature |
Volume | 534 |
Issue number | 7606 |
Early online date | 8 Jun 2016 |
DOIs | |
Publication status | Published - 9 Jun 2016 |
Keywords
- Interstellar medium
- Galaxies and clusters