Durham University Institute for Computational Cosmology visit

Visit to the Durham University Institute for Computational Cosmology

I spent last week hosted by the Institute for Computational Cosmology at Durham University, staying in “Castle” one of the historic colleges of the university, an actual, honest to goodness Castle and a World Heritage Site.


Durham University has a lot to offer, a huge cosmology and astronomy department, and I was honored to give a talk “Modified gravity on the Virgo cluster scale with Zoom Simulations” at the weekly seminar series there.


The Making of Chameleon f(R) gravity on the Virgo cluster scale

Screenshot 2015-07-20 18.10.50

This visit all came about because I saw, years ago during my daily astro-ph browsing habit an intriguing new paper by Baojiu Li “ECOSMOG: An Efficient Code for Simulating Modified Gravity” coauthored by my co-advisor with Dr. Li leading the way. I approached my advisor wanting to run some simulations with this new offshoot of his code. I had been actively attending a general relativity reading group, and had recently lead the discussion of an overview of modified gravity theories and became increasingly interesting in the rich mathematics and theory behind this field cooked up to offer alternative explanations for either dark matter or dark energy to the standard cosmological models. No particular theory was or is favored over the standard model of cosmology, but such theories offer a test ground to explore the consequences at all scales of tweaking our accepted theory of gravity (general relativity) at a fundamental level.

Screenshot 2015-07-20 18.10.50(2)

 It was a fascinating new possibility that I could simulate some of the consequences of one of these theories. I was already working on zoom simulations in a Virgo cluster like environment in standard  Lambda-CDM cosmology to explore globular cluster formation, and it was a natural choice to simulate a similar environment in a modified gravity model, and see if we could make predictions to help confirm or rule out a particular suite of models.

I went forward with the work and often communicated with Dr. Li (promoted to senior Lecturer at Durham) who was extremely helpful as we teased out the issues in setting up the simulations, and later the physical meaning and predictions, as an expert in the field of modified gravity and having developed the majority of the necessary modifications to simulate it. Gradually, I became an expert myself and the project grew to be of equal importance to my thesis as the simulations I was performing in standard “Lambda-CDM” cosmology and became a theme of my personal research.

Finally, I was ready to publish the findings, and looking back it was clear that Dr. Li was a full collaborator and should be credited as a co-author not simply acknowledged if he would endorse my findings. I was nervous to broach the subject, after all we had only communicated via email, albeit extensively, and I was worried he would turn me down. To my great pleasure, he accepted the co-authorship in name in addition to in practice, and he gave extensive help revising the paper to present things in the most polished light  and helped give the paper the gravitas that it was easily accepted in my target journal with only minor revisions.

Screenshot 2015-07-20 18.11.43


Only months after this, as I was preparing my postdoctoral fellowship proposals did I finally talk to Dr. Li on Skype for the first time. This past week it was excellent to finally meet with him and his students and postdocs in person who are some of the core people in the fascinating field and to plan additional work and collaboration. The whole experience showed me how international and open science can be, and to this day I continue to comb the arXiv not only for interesting papers relevant to my current research, but also to follow up and coming areas, potentially unexpected, from around the world. I’m lucky to have “stumbled upon” Dr. Li and his group and looking forward to more collaboration in the coming years!


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