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Mihran Vardanyan
Cosmologist (DPhil, University of Oxford) and creator of the iCosmos cosmology calculator.
Biography
Mihran Vardanyan is a cosmologist who earned his DPhil in cosmology at the University of Oxford, supervised by Joseph Silk and Roberto Trotta. He developed iCosmos during his research years at Oxford Astrophysics, where his work applied Bayesian model selection to the curvature and size of the Universe.
His DPhil at Oxford Astrophysics was supervised by the cosmologist known for Silk damping Joseph Silk and the astrostatistician Roberto Trotta.
Mihran Vardanyan on LinkedIn · Mihran Vardanyan on Google Scholar
Research
The curvature of the Universe as a model-comparison problem (2009)
A three-way Bayesian comparison of flat, open and closed universes. With the data then available, the probability that the Universe is spatially infinite was found to lie between 67% and 98%, depending on the choice of priors, with a prior-independent lower limit of NU > 5 Hubble spheres (99%). The paper also argued that curvature below about |Ωk| ~ 10⁻⁴ cannot be told apart from exact flatness by future CMB and BAO observations.
Model-averaged constraints on curvature and size (2011)
Bayesian model averaging gives parameter constraints that account for the uncertainty about which cosmological model is correct. Applied to curvature while allowing for evolving dark energy, it gave a curvature radius Rc > 42 Gpc (99%), corresponding to a lower limit of NU > 251 Hubble spheres (99%) on the size of the Universe.
Design of baryon acoustic oscillation surveys (2010)
With D. Parkinson and collaborators: how the optimal redshift range and area of a BAO survey change when spatial curvature is included as a free parameter and when external data sets are added.
His model-comparison analysis of spatial curvature (Vardanyan, Trotta & Silk 2009) was featured in New Scientist (May 2009), and his Bayesian model-averaging constraints on the curvature and size of the Universe (Vardanyan, Trotta & Silk 2011) in MIT Technology Review (February 2011), The Hindu (2011) and Space.com.
Publications
- M. Vardanyan, R. Trotta & J. Silk (2009), How flat can you get? A model comparison perspective on the curvature of the Universe, MNRAS 397, 431.
- M. Vardanyan, R. Trotta & J. Silk (2011), Applications of Bayesian model averaging to the curvature and size of the Universe, MNRAS Letters 413, L91.
- D. Parkinson, M. Kunz, A. R. Liddle, B. A. Bassett, R. C. Nichol & M. Vardanyan (2010), Optimizing baryon acoustic oscillation surveys II: curvature, redshifts and external data sets, MNRAS 401, 2169.
iCosmos
He developed iCosmos during his DPhil. It first went online in 2008 and was recognised in the University of Oxford's OxTALENT awards in 2012 (IT innovation). It was one of the calculators used to test the cosmology code of Astropy and the growth factor of COLOSSUS, and it is listed by the NASA/IPAC Extragalactic Database and recommended by the Hubble Frontier Fields team. The research, theses and courses that use it are listed on the About page.
To cite the calculator: Vardanyan, Mihran. iCosmos V4: Cosmology Calculator. https://icosmos.co.uk/
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