Conference on Shocks and Particle Acceleration in Novae and Supernovae

Thursday, June 23 —
Friday, June 24, 2016

Simons Foundation
Gerald D. Fischbach Auditorium
160 Fifth Avenue
New York, New York

Saturday, June 25, 2016
Columbia University
Pupin Hall
538 W. 120th Street
New York, New York

On June 23 and 24, 2016, about 60 international researchers working in the fields of novae and supernovae met at the Simons Foundation in New York City to discuss the physics of shocks and particle acceleration in these transient astrophysical events. The fields of novae and supernovae broke off from one another when they were first identified as physically distinct events in the 1930s, by Baade and Zwicky. However, the growing appreciation—based on an ever-expanding array of multi-wavelength observations—that shocks play a crucial role in the appearance of both of these systems motivated us to unite these fields once again. The workshop was comprised of pedagogical overview talks meant to bridge the knowledge gap between these fields, interspersed with long open discussion periods aimed at addressing particular aspects of each phenomena.

The workshop began with an overview by Tommy Nelson (University of Pittsburgh) of the ways that shocks manifest in novae across the electromagnetic spectrum, from radio to gamma rays. Teddy Cheung (NASA Goddard) provided an overview of the unexpected recent discovery by NASA’s Fermi telescope that novae produce luminous ~ GeV gamma-ray emission. This emission is believed to arise either from the Compton scattering of ambient optical photons from electrons accelerated to ultra-relativistic velocities by the nova, or to the decay of π0 produced by collisions between shock-accelerated relativistic protons. Bill Wolf (University of California, Santa Barbara) described the physics of thermonuclear runaway on the surface of accreting white dwarfs, the engine behind novae. Brian Metzger (Columbia University) provoked the audience by suggesting that most nova optical emission are powered indirectly by shocks, contrary to standard theory.

The Thursday afternoon session addressed the signatures of shock waves in the time-dependent emission-line spectra caused by different ejecta components. Raffaella Margutti (Northwestern University) discussed the X-ray emission from shock waves in young, unresolved supernovae, while Steve Reynolds (North Carolina State University) discussed similar emission from shocks in older galactic supernova remnants. On Friday morning, Damiano Caprioli (University of Chicago) described the first particle-in-cell plasma simulations showing the process of diffusive particle acceleration (Fermi acceleration). Our discussions identified a previously neglected discrepancy regarding the low-electron-acceleration efficiency, which is inferred from supernova remnants and PIC simulations, versus the much higher efficiencies inferred from unresolved supernovae. Future methods for analyzing the supernova data were agreed upon to better quantify this discrepancy and its cause.

Overall, the workshop was considered a great success. An informal survey indicated that, for the vast majority of participants, this was the first time they had attended a conference combining novae and supernovae, which effectively brought researchers in each field up-to-speed on the other. Raffaella Margutti commented, “It is definitely one of the conferences where I learned the most.” Steve Reynolds commented, “[The conference] was a real eye-opener.” Each moment of the lengthy discussion sessions was filled with dialogue, revealing many hitherto unrecognized areas of overlap between these research fields.

Schedule and Slides

Thursday, June 23 – Fischbach Auditorium, Simons Foundation
8:30−8:45 Introductory Remarks
8:45−9:15 Overview: Novae and Shocks, Tommy Nelson
9:15−9:45 Gamma-Rays from Novae, Teddy Cheung
9:45−10:15 Overview: Shocks in SNe, Nathan Smith
10:15−10:45 Coffee
Basics of Novae and Supernovae
10:45−11:15 Thermonuclear Runaway, Bill Wolf
11:15−11:45 Optical Light Curves of Novae and Supernovae, Ashley Pagnotta Slides (PDF)
11:45−12:00 Are Nova Light Curves Shock-Powered? Brian Metzger Slides (PDF)
12:00−12:25 Moderated Discussion
Discussion Leaders: Brad Schaefer (TBC) and Mike Shara
  • ‘Can nova outflows produce internal shocks?’
  • ‘Causes of mass loss in supernova progenitors?’
  • ‘Reasons for light curve diversity?’
12:25−2:00 Lunch
Optical Spectra
2:00−2:30 Spectral Diagnostics of Novae, Fred Walter
2:30−3:00 Spectral Diagnostics of Supernovae, Ryan Chornock
3:00−3:30 Moderated Discussion
Discussion Moderator: Bob Williams
  • ‘What is the evidence for multiple velocity components and shocks in nova and supernova spectra?’
  • ’How is spectral line formation from shocks different in nova and supernovae?’
3:30−4:00 Coffee
X-rays from Novae and SNe
4:00−4:30 X-rays from Nova Shocks, Koji Mukai Slides (PDF)
4:30−5:00 X-rays from Young Supernovae, Raffaella Margutti
5:00−5:30 X-rays from Supernova Remnants, Steve Reynolds
Friday, June 24 – Fischbach Auditorium, Simons Foundation
Gamma-Ray Emission
8:45−9:15 Gamma-Ray Emission from Nova Shocks, Guillaume Dubus
9:15−9:45 Particle Acceleration in Non-Relativistic Shocks, Damiano Caprioli
9:45−10:15 Gamma-Ray Emission in SN Remnants, Jacco Vink
10:15−10:45 Coffee
10:45−11:10 Non-Thermal X-rays from Novae, Indrek Vurm Slides (PDF)
11:10−11:35 TeV Observations, Reshmi Mukherjee Slides (PDF)
11:35−12:10 Moderated Discussion
Discussion Leaders: Brian Metzger, Margarita Hernanz
  • ‘Shock acceleration in novae versus supernovae’
  • ’Leptonic versus hadronic?’
12:10−1:40 Lunch
Nova Environments and Outflow Geometry
1:40−2:10 CV and Nova Environments, Christian Knigge
2:10−2:40 Overview of Nova Outflow Geometry, Tim O’Brien Slides (PDF)
2:40−3:10 Proto-Planetary Nebulae, Orsola deMarco
3:10−3:40 Coffee
3:40−4:10 Massive Star Winds, Stan Owocki
4:10−4:40 Mass Loss from Binary Stars, Ondrej Pejcha
4:40−5:30 Moderated Discussion
Discussion Leader: Joe Patterson
  • ‘Geometry of nova outflows: binarity vs. rotation?’
  • ’Predictions of super-Eddington outflow models’
Saturday, June 25 – Columbia, Pupin Hall, Center for Theoretical Physics (8th Floor)
8:45−9:05 New Methods of Transient Discovery, Eran Ofek
Radio Emission from Novae and Supernovae
9:05−9:35 Radio Observations of Novae, Justin Linford
9:35−9:55 Radio Emission in Novae, Jennifer Weston
9:55−10:25 Coffee
10:25−10:55 Radio Observations of Supernovae, Laura Chomiuk
10:55−11:25 Radio Emission in Supernovae, Rodolfo Barniol-Duran
11:25−12:00 Moderated Discussion
Discussion Leaders: Jeno Sokoloski, Michael Rupen
  • ‘Are radio-producing shocks the same as those producing gamma-rays’
  • ‘Radio-emitting electrons leptonic or hadronic?’
Slides (PDF)
12:00−1:30 Lunch
1:30−2:00 Dust Formation in Stellar Eruptions, Chris Kochanek
2:00−2:30 Radiative SN Shocks, John Raymond
2:30−3:00 Dust Formation in Novae, Andrew Helton
3:00−3:30 Coffee
3:30−4:00 Theory of Dust Formation, Jonathan Rawlings
4:00−5:30 Open Discussion and Wine, Laura Chomiuk


Rodolfo Barniol-Duran Purdue University
Damiano Caprioli Princeton University
Poonam Chandra Tata Institute
Teddy Cheung Naval Research Laboratory
Ryan Chornock The Ohio University University
Orsola deMarco Macquarie University
Guillaume Dubus Institut de Planétologie et d’Astrophysique de Grenoble
Andrew Helton Stratospheric Observatory for Infrared Astronomy
Margarita Hernanz Institut d’Estudis Espacials de Catalunya
Christian Knigge University of Southampton
Chris Kochanek The Ohio State University
Justin Linford Michigan State University,
Raffaella Margutti North Carolina State University
Koji Mukai NASA/GSFC
Reshmi Mukherjee Columbia University
Ehud Nakar Tel Aviv University
Tommy Nelson University of Minnesota
Tim O’Brien The University of Manchester
Eran Ofek Weizmann Institute
Stan Owocki University of Delaware
Ashley Pagnotta American Museum of Natural History
Joe Patterson Columbia University
Ondrej Pejcha Princeton University
John Raymond Harvard-Smithsonian Center for Astrophysics
Jonathan Rawlings University College London
Steve Reynolds North Carolina State University
Michael Rupen National Radio Astronomy Observatory: Socorro
Michael Shara American Museum of Natural History
Nathan Smith University of Arizona
Jacco Vink Astronomical Institute Anton Pannekoek
Indrek Vurm Columbia University
Fred Walter Stony Brook University
Jennifer Weston Columbia University
Bob Williams Space Telescope Science Institute
Bill Wolf UC Santa Barbara