Caltech Home > PMA Home > People > E. S. (Sterl) Phinney
open search form

E. S. (Sterl) Phinney

Professor of Theoretical Astrophysics
Sterl Phinney
Contact information for E. S. (Sterl) Phinney
Contact Method Value
Mail Code: MC 350-17
Phone: 626-395-4308
B.S., Caltech, 1980; Ph.D., University of Cambridge, 1983. Assistant Professor, Caltech, 1985-91; Associate Professor, 1991-95; Professor, 1995-; Executive Officer, 2013-16.
Research Areas: Physics; Astronomy

Research Interests

Theoretical High-Energy Astrophysics and Gravitational Wave Astrophysics

My students, postdocs and I use pencils, chalk and computers to explore the extremes of the universe: the deepest potential wells, the densest matter, the hottest plasma; i.e. black holes, neutron stars and the early universe. The goals are to understand how they work, and how they came to be.

Over the course of my career, I have worked on the theory of black hole accretion, active galactic nuclei, relativistic magnetohydrodynamic jets, galaxy mergers, stellar dynamics and multiple star interactions in globular clusters, tidal disruption and extreme mass-ratio inspirals on black holes, predictions of sources of gravitational waves at nHz, mHz and kHz frequencies, the LISA space mission (I chaired the US Mission Definition Team 1997-2001, and served on the LISA International Science Team and chaired its Sources and Data Analysis Working Group 2001-2011, and was PI of the Big Bang Observer study), X-ray binaries and binary pulsars.  I am currently on the science team of ULTRAsat, and a proposed ultraviolet survey satellite UVEX.

Many long-standing questions about these extremes of physics can be answered by combining electromagnetic, particle and gravitational wave observations of the sources. Examples of such questions are: What is the nature of pulsar winds, and how do they affect companion stars? What happens when a star is tidally disrupted by a supermassive black hole? How do accretion disks work? When and how did the black holes in galactic nuclei form and grow? What powers gamma-ray and fast radio bursts? How do single and binary neutron stars and black holes form and merge?

My current research, with students, postdocs, and external collaborators, is  on the formation and evolution of millisecond pulsars and their companions, on magnetars and exotic supernova interactions, on the aftermath of tidal disruption of stars by black holes and the uses and sources of Fast Radio Bursts. This work combines in individual problems high-energy physics, plasma physics, magnetohydrodynamics, stellar structure and atmospheres, climate physics and gravitational physics, and has close connections to observations at wavelengths from radio through gamma-ray. As Co-PI of the Caltech-UCSB-UCB ZTF theory network, I also spend time trying to decipher the many mysterious objects being discovered by ZTF.  So many ideas and so little time mean there is always room for another good student.

Besides deciphering the extremes of the universe, I also have a hobby of figuring out simple quantitative explanations of everyday phenomena. This is fascinating, makes for good conversation and financial investments, and is valuable practice for research in astrophysics. You can learn and contribute to this in my Order of Magnitude Physics course.

Selected Awards

Alfred P. Sloan Foundation Fellow. ASCIT Excellence in Teaching Award. Warner Prize of the American Astronomical Society. Salpeter Lecturer, Cornell University. Presidential Young Investigator. Radboud University Excellence Professor.

Professional Societies

Fellow of the American Physical Society. American Astronomical Society. Royal Astronomical Society.


Ph 136 abc. Applications of Classical Physics. 9 units (3-0-6): first, second, third terms. Prerequisites: Ph 106 ab or equivalent. Applications of classical physics to topics of interest in contemporary "macroscopic'' physics. Continuum physics and classical field theory; elasticity and hydrodynamics; plasma physics; magnetohydrodynamics; thermodynamics and statistical mechanics; gravitation theory, including general relativity and cosmology; modern optics. Content will vary from year to year, depending on the instructor. An attempt will be made to organize the material so that the terms may be taken independently. Ph 136a will focus on thermodynamics, statistical mechanics, random processes, and optics. Ph136b will focus on fluid dynamics, MHD, turbulence, and plasma physics. Ph 136c will cover an introduction to general relativity. Offered in alternate years. Not offered 2021-22.
Ph 101. Order-of-Magnitude Physics. 9 units (3-0-6): third term. Emphasis will be on using basic physics to understand complicated systems. Examples will be selected from properties of materials, geophysics, weather, planetary science, astrophysics, cosmology, biomechanics, etc. Given in alternate years. Instructor: Phinney.
Ay 102. Physics of the Interstellar Medium. 9 units (3-0-6): second term. Prerequisites: Ay 20 is recommended. An introduction to observations of the interstellar medium and relevant physical processes. Phases of the gaseous interstellar medium. Thermal balance in neutral and ionized gas. Molecular gas and star formation. Structure and hydrodynamic evolution of ionized regions associated with massive stars; supernovae. Global models for the interstellar medium. Interstellar and circumstellar dust. Instructor: Phinney.
Ay 121. Radiative Processes. 9 units (3-0-6): first term. Prerequisites: Ph 106 bc, Ph 125 or equivalent (undergraduates). The interaction of radiation with matter: radiative transfer, emission, and absorption. Compton processes, coherent emission processes, synchrotron radiation, collisional excitation, spectroscopy of atoms and molecules. Instructor: Phinney.

Selected Publications

My publications are listed here.