Christopher Michael Hirata (born November 30, 1982) is an American

cosmologist Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...

and astrophysicist. Hirata was 13 years old when he won the gold medal in 1996 at the

International Physics Olympiad The International Physics Olympiad (IPhO) is an annual physics competition for high school students. It is one of the International Science Olympiads. The first IPhO was held in Warsaw, Poland in 1967. Each national delegation is made up of at ...

. He received a bachelor's degree in Physics at

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

in 2001, at the age of 18. He received his PhD under the supervision of

Uroš Seljak Uroš Seljak (born 13 May 1966 in Nova Gorica) is a Slovenian cosmologist and a professor of astronomy and physics at University of California, Berkeley.

in 2005 from

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

Astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

(thesis: "Weak Gravitational Lensing Theory and Data Analysis"). From 2005 to 2007 he was a visiting scholar at the

Institute for Advanced Study The Institute for Advanced Study (IAS), located in Princeton, New Jersey, in the United States, is an independent center for theoretical research and intellectual inquiry. It has served as the academic home of internationally preeminent scholar ...

. From 2006 to 2012 he was assistant professor and then full professor at Caltech before moving to the

Ohio State University The Ohio State University, commonly called Ohio State or OSU, is a public land-grant research university in Columbus, Ohio. A member of the University System of Ohio, it has been ranked by major institutional rankings among the best publ ...

the following academic year in the same capacity. He is currently a professor at OSU's Center for Cosmology and AstroParticle Physics (CCAPP).

Research

Hirata's research emphasis is

Cosmic Microwave Background In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all spac ...

(CMB),

Dark energy In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the univer ...

and

accelerating expansion of the universe Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered durin ...

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-l ...

s and the

large-scale structure of the universe The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these obj ...

(and the formation of these structures, the Reionization epoch), and

gravitational lens A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...

es as a tool of

Cosmology Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount (lexicographer), Thomas Blount's ''Glossographia'', and in 1731 taken up in ...

. Hirata works both in theory and in the analysis of observational data as well as in the design of telescopes (specifically NASA's next generation of space telescopes). His overarching focus is on cosmology and on

. Hirata is considered a leading exponent of precision cosmology, combining interdisciplinary computer studies, theoretical studies, and observational astronomy including instrument development. In 2010, with Dmitriy Tseliakhovich, he pointed to an unprecedented effect in

cosmological perturbation theory In physical cosmology, cosmological perturbation theory is the theory by which the ''evolution of structure'' is understood in the Big Bang model. It uses general relativity to compute the gravitational forces causing small perturbations to grow an ...

for the calculation of the formation of the first structures in the universe. It is based on the fact that the speed of sound in

baryonic matter In particle physics, a baryon is a type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified ...

(as opposed to

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

) decreased drastically (from relativistic to thermal velocities) when the first atoms formed ( recombination epoch), which leads to supersonic velocity currents of baryonic matter (which under gravitational influence of faster dark matter moves) and quadratic perturbation terms. According to Hirata and Tseliakhovich, this leads to a suppression of the formation of the first structures with observable effects. With others, he initiated a program for analyzing information from astronomical data for possible inferences on fundamental questions of particle physics and what it might suggest for creating new observation programs. A central question is whether the acceleration of the universe indicates dark energy (retention of

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

but with an additional dynamic

scalar field In mathematics and physics, a scalar field is a function (mathematics), function associating a single number to every point (geometry), point in a space (mathematics), space – possibly physical space. The scalar may either be a pure Scalar ( ...

) or a modification of the general theory of relativity. He is a member of NASA's proposed

Nancy Grace Roman Space Telescope The Nancy Grace Roman Space Telescope (shortened as Roman or the Roman Space Telescope, and formerly the Wide-Field Infrared Survey Telescope or WFIRST) is a NASA infrared space telescope currently in development and scheduled to launch by Ma ...

(previously named the Wide Field Infrared Survey Telescope space telescope).

Accolades

* 2012 - Presidential Early Career Award (

PECASE The Presidential Early Career Award for Scientists and Engineers (PECASE) is the highest honor bestowed by the United States government on outstanding scientists and engineers in the early stages of their independent research careers. The White ...

) * 2013 -

Simons Foundation The Simons Foundation is a private foundation established in 1994 by Marilyn and Jim Simons with offices in New York City. As one of the largest charitable organizations in the US with assets of over $5 billion in 2022, the foundation's mission ...

Investigator * 2014 -

Helen B. Warner Prize The Helen B. Warner Prize for Astronomy is awarded annually by the American Astronomical Society to a young astronomer (aged less than 36, or within 8 years of the award of their PhD) for a significant contribution to observational or theoretical ...

* 2018 -

New Horizons in Physics Prize The Breakthrough Prize in Fundamental Physics is one of the Breakthrough Prizes, awarded by the Breakthrough Prize Board. Initially named Fundamental Physics Prize, it was founded in July 2012 by Russia-born Israeli entrepreneur, venture capita ...

for fundamental contributions to understanding the formation of the first galaxies in the universe and for sharpening and applying the most powerful tools of precision cosmology

References

{{DEFAULTSORT:Hirata, Chris American cosmologists American astrophysicists People from Ypsilanti, Michigan California Institute of Technology alumni Princeton University alumni Ohio State University faculty American people of Japanese descent 1982 births Living people