Adam Ingram

profile image

Adam Ingram

Royal Society URF

I am a Royal Society University Research Fellow. I completed my PhD at the University of Durham in 2012, and was awarded the 2012 Michael Penston Thesis Prize, for the best astronomy PhD thesis in the UK that year, by the Royal Astronomical Society. I then moved to the University of Amsterdam, first as a postdoc (2012-1014) and then as an NWO Veni research fellow (2014-2017). I moved to Oxford to start my University Research Fellowship in October 2017.

My research focuses on accreting compact objects, mainly stellar-mass black holes accreting gas from their binary partner in a so-called X-ray binary system, but I am also interested in accreting neutron stars and active galactic nuclei. I analyse and model X-ray observations of these systems in order to learn about the very strong gravitational field present close to the event horizon. In particular, I develop and use sophisticated techniques that exploit the rapid stochastic variability seen in the X-ray signal in order to map the accretion flow in the immediate vicinity of the black hole. This includes using Doppler shifts to detect a wobble of the inner accretion flow predicted by General Relativity known as Lense-Thirring precession, modelling aperiodic X-ray variability as inward propagating fluctuations of the density of the accretion disk, and using light crossing delays for the purposes of reverberation mapping.

In general, I am interested in using state-of-the-art Fourier techniques in order to uncover the physical mechanism driving the rapid variability observed in the X-ray flux of accreting compact objects, and also exploiting this variability to map the inner regions of the accretion flow - which are too small to directly image.

One of the main phenomena I am interested in are the quasi-periodic oscillations (QPOs) routinely observed in the X-ray flux from black hole X-ray binaries. I have led work to suggest that these oscillations in brightness are caused by Lense-Thirring precession of the inner accretion flow, which is a relativistic effect resulting from a spinning black hole dragging the surrounding spacetime with it as it rotates. I have also led work to model the aperiodic variability from the same objects as fluctuations in the mass accretion rate onto the black hole. More recently, I have been working on cutting edge reverberation mapping techniques that measure the time delay experienced by X-rays that reach us via reflection from the accretion disk compared with X-rays that reach us directly from the central source. In addition, I am very excited about the upcoming advent of space-based X-ray polarimetry, and have been developing techniques to measure the accretion flow and black hole parameters using rapid variability of the polarisation degree and angle. A summary of my published papers can be found at this link:
https://tinyurl.com/y95ad7de

Here are some links to press releases and magazine articles about work I have been involved in.

Breakthrough in simulations: rapidly-spinning black holes launch tilting jets (UvA press release)
http://api.uva.nl/content/news/2017/11/breakthrough-in-simulations.html?...

Gravitational vortex provides new way to study matter close to a black hole (ESA press release)
http://sci.esa.int/xmm-newton/58072-gravitational-vortex-provides-new-wa...

Black Hole Makes Material Wobble Around It (NASA press release)
https://www.jpl.nasa.gov/news/news.php?feature=6567

Seeing a Black Hole’s Gravitational Vortex (Sky & Telescope article)
http://www.skyandtelescope.com/astronomy-news/black-hole-gravitational-v...

Gravitational vortex detected around black hole (Astronomy article)
http://www.astronomy.com/news/2016/07/gravitational-vortex-detected-arou...