I'm a postdoc in the astrophysics group at MIT, where I've been since August 2018.
I grew up in Newcastle, Australia and did my undergraduate science degree at the Australian National University in Canberra. For my final research-focused year in 2008, I participated in a survey to detect transiting exoplanets and investigated the problem of false-positive detections caused by stellar eclipsing binaries (Evans & Sackett, 2010). Between 2009-2010, I was at the University of Sydney doing a Masters research degree, where I used aperture masking interferometry with the VLT, Keck, and Hale telescopes to search for substellar companions around nearby young stars. Although we didn't detect any substellar companions, I was able to use the null detection with the sensitivity limits of our survey to constrain the frequency of such objects as a function of mass and orbital semimajor axis (Evans et al., 2012).
At the end of 2010, I started a DPhil at the University of Oxford and turned my attention to the atmospheric characterisation of transiting exoplanets. In this work, I developed an interest in the application of Bayesian methods such as Gaussian processes (GPs) to the treatment of instrumental systematics in transit lightcurve data. GPs offer a number of advantages over traditional decorrelation methods, such as not requiring an explicit functional form to be specified for the often-poorly-understood systematics. Instead, the high level properties of the signal covariance are parameterised, allowing complex correlations to be marginalised over relatively low-dimension parameter spaces. I used GP models to analyse transit and eclipse lightcurves for the hot Jupiters HD 189733b and HD 209458b (Evans et al., 2013; Evans et al., 2015).
In 2014 I moved to Exeter, where I focused mostly on transit and eclipse observations made with space-based telescopes at optical and infrared wavelengths. Over the last few years, I've led numerous programs as Principal Investigator, totalling hundreds of hours on Hubble and Spitzer. Recently, I've been studying the ultrahot gas giant WASP-121b in some detail, detecting water in its transmission spectrum (Evans et al., 2016), showing that the dayside hemisphere has a thermal inversion (Evans et al., 2017), and uncovering evidence for near-UV/optical absorbers at high-altitude on the day-night boundary (Evans et al., 2018).
Image: Seven Mile Beach near Forster, Australia