Research
Summary:
In the grandest sense I'm interested in why galaxies look the way they do and how they evolve. Currently my focus is on AGN feedback and more specifically the role of compact jets in 'quasar' mode feedback. I'm also interested in multi-wavelength approaches to probing as many different aspects of AGN feedback as possible. I am the co-leader of the 'Quasar Feedback Survey' an international collaboration studying quasar feedback centered around a sample of galaxies that I selected and led the initial VLA observations for, which since then has received time with MUSE, ALMA, APEX, eMERLIN and GMRT.
Radio jets in local quasars:
One of the main goals of my work so far has been identifying the mechanism by which quasars impact their host galaxies. Specifically, this has focused on identifying and characterizing galactic scale jets in local 'radio-quiet' quasars using ~0.25-1 arcsec resolution radio continuum imaging from the VLA. In my first paper I combined radio imaging with integral field spectroscopy (IFS) from GMOS and VIMOS for 10 quasars. Specifically we find a high incidence of compact jets (~60%) and evidence for jet-ISM interactions in all of these. Subsequently I have expanded this sample to 42 using VLA data for which I was the PI. By combining my radio observations with archival IR photometry and optical spectroscopic observations we found that the radio emission in at least 57% is dominated by the AGN and find evidence that the size of the radio emission is linked to the ionised emission line properties (luminosity and FWHM). This work has been submitted for publication and an earlier version has been published as Chapter 4 of my Thesis. Moving forward, we are pushing to higher spatial resolutions using new eMERLIN observations (for which I'm a CoI) and ALMA 100GHz imaging (for which I led the observing proposal as PI). Finally I'm working on comparing my sample to 'compact steep spectrum' and 'gigahertz peaked spectrum' sources, by using GMRT data, for which I was PI, to investigate the radio SED's of my full sample of 42 quasars and studying the sources presented in Jarvis+19 in radio polarization.
The impact of quasars on their host galaxies:
The second main branch of my work so far and of the Quasar Feedback Survey in general. In my 2019 paper I used data from APEX (observations on which I was PI) and UV-IR SED fitting to discover that the majority of the Quasar Feedback Survey pilot sample studied reside in starburst galaxies with no indication of an impact of the AGN on the total molecular gas reservoir. This work is being expand on using APEX and ALMA data looking at multiple CO transitions of all 17 type 2 quasars in the Quasar Feedback Survey in work being led by a PhD student I'm mentoring (Stephen Molyneux). I also began an investigation into the impact of AGN on their host galaxies' molecular gas content using the Illustris TNG simulations, work that has been taken over by a PhD student I'm mentoring (Samuel Ward).
We additionally have MUSE IFS data for the 17 type 2 quasars in the Quasar Feedback Survey. We will use these data to study the ionised gas outflows in these sources. This will expand upon my work in Jarvis+19, with the larger FOV, higher spatial resolution and higher sensitivity of the MUSE data allowing for a significant improvement on the possible analysis. This work is currently being led by a PhD student I'm mentoring (Aishwarya Girdhar).
Imprints of compact jets in survey data:
I am also interested in extending this work to even more statistically significant numbers by extracting as much information as possible from current radio and spectroscopic surveys (primarily SDSS and FIRST). So far, through work led by Stephen Molyneux under my co-supervision (Molyneux+19), we have found a higher incidence of high velocity outflows in SDSS selected AGN when the radio emission is confined to the SDSS fiber, possibly indicative of jet-ISM interactions. Follow up experiments include getting VLA detection or significantly lower upper limits on the AGN sample which were undetected in both NVSS and FIRST. I am interested in conducting similar studies on upcoming surveys with deeper radio imaging (e.g. VLASS) or at higher redshift (through e.g. near IR spectroscopic surveys like MOONS).
Instrumentation
Although I haven't had the opportunity to pursue instrumentation projects as part of my PhD it remains of particular interest to me. As part of my undergraduate research I designed a data simulation code and led the initial design and testing of the calibration system for the 'wide integral field infrared spectrograph' (WIFIS; see Sivanandam+18 and Meyer+16). In 2014 I took part in the Dunlap Institute's 'Instrumentation Summer School' and I assisted in leading the optical design segment of the school in 2013. I am very much interested in future instrumentation work if opportunities arise.
Press release based on work I'm involved in:
As part of work I co-authored investigating the X-ray properties of one of my sample (Lansbury+18) Chandra produced an article, which was also used as the ESA picture of the week 6th May 2019. (Thanks to NASA/CXC/A. Hobart)