Cosmic Explosions

Over the last years and decades, large surveys and new observatories have enabled an exquisite view onto the time-variable night sky. A plethora of transients has been discovered, for example supernovae, hypernovae, gamma-ray bursts, merging compact objects and the enigmatic fast radio bursts. Multi-messenger astronomy allows us to observe transients in the 'usual' electromagnetic light (e.g. optical, X-ray and radio), but also in neutrinos and gravitational waves. All transients are related to fascinating physics and, in this seminar, we will try to get an overview of the large zoo of explosive phenomena and what they can tell us about the Universe we live in.

This is a graded "Masterpflichtseminar" (MVSem) aimed at master students. Students will pick a topic from the below list (or suggest another adequate topic) and present it in a talk. An additional written report about the presentation is required. In the first session, a brief introduction to the various topics is given, and dates for the student presentations and topics are chosen.

Lecturer: Dr. Fabian Schneider

When and where? Summersemester 2020, Fridays, 9:15-11:00 online via Zoom as long as the Corona lock-down persists and the University is closed; depending on the situation, we may be able to return to the seminar room (1st floor) at ARI at a later time. For the Zoom Meeting ID and password, you should have received an email. If not, please contact me.

Registration: via the Physics Uebungssystem

Organisation and further information

• Final grade: 50% talk, 50% report
• Talk: 30min + 15min discussion/feedback; you should know how to give a good and effective talk from your bachelor studies, so make use of this; be reminded that your fellow students need to be able to understand what you are talking about such that they can engage in the final discussion; please send me a PDF version of your talk before your presentation such that I can upload it to the Uebungssystem
• Report: ~10 pages, detailing the talk, explaining the topic; not just a pure summary of the talk, but also explain the topic choices, the literature used, why presented in the way you did, why did you decide to skip certain topics etc.; report due 1 week after your oral presentation
• Active participation required (not just attendance!)
• Meet with supervisor before your talk to discuss the topic and your talk structure; meet latest 1 week before your talk such that you can implement new suggestions (better: 2 weeks before talk); make an appointment!
• Paper/journal access: We suggest using The SAO/NASA Astrophysics Data System (see also the links provided below). Most published papers are also available on the arXiv preprint server if you cannot access the published paper version via the journal homepage. From within the University network, you should have access to most journals via the University's library. From home, you can use your student ID and a VPN client to log into the University network and then access journals (see https://www.urz.uni-heidelberg.de/en/vpn). Alternatively, you can use the HEIDI catalogue at https://katalog.ub.uni-heidelberg.de. If you can still not access a resource, just let me know and I will do my best to help you.

Schedule

Date	Presentation 1	Presentation 2
24.04.	Schneider: Introduction; date and topic assignments
01.05.	Public holiday (Tag der Arbeit)
08.05.
15.05.
22.05.	Niedeggen: Type Ia supernovae
29.05.	Kuhn: Kilonovae and r-process
05.06.	Traenkle: Compact-object mergers and gravitational-wave astronomy
12.06.	Neumann: Pair-instability supernovae
19.06.	Piotter: Soft-gamma repeater
26.06.	NA	NA
03.07.
10.07.	Temaj: Core-collapse supernovae	Tschesche: Luminous-blue variables and supernova impostors
17.07.	Walberg: Electron-capture supernovae
24.07.
31.07.	Exam week?

Topics

Below is a list of interesting transients in alphabetical order:

Anti-transient: disappearing red-supergiant stars

• Theoretical lightcurve model from neutrino-mediated mass-loss/ejecta of a star collapsing to a black-hole: Lovegrove and Woosley 2013
• Observations and transient searches for collapsing stars: Kochanek et al. 2008; first candidates: Gerke et al. 2015, Adams et al. 2017a and Adams et al. 2017b
• Connected to missing red-supergiant problem: see progenitors of core-collapse supernovae in CCSNe section, Smartt 2009

Classical and recurrent novae

• Recent review: Starrfield et al. 2016
• Classic (older) review: Gallagher and Starrfield 1978

Compact-object mergers and gravitational-wave astronomy

• Gravitational-wave astronomy: a general introduction/review (Schutz 1999, Sathyaprakash and Schutz); summary of observing runs O1 and O2 of aLIGO/VIRGO: Abbott et al. 2019
• The first BH-BH merger: Abbott et al. 2016
• The first NS-NS merger: Abbott et al. 2017 and its multi-messenger astronomy (Abbott et al. 2017)

Core-collapse supernovae

• Progenitors of core-collapse supernovae: review paper by Smartt 2009; link to missing red-supergiant problem and stars directly collapsing to black holes (updated paper on latter aspect: Smartt 2015)
• Review papers on theory: "Theory of Core-Collapse Supernovae" by Janka et al. 2007 or "Explosion Mechanisms of Core-Collapse Supernovae" by Janka 2012; German popular book written by Janka (available at Uni Heidelberg library) https://www.springer.com/de/book/9783827420725
• SN 1987A and its neutrino burst: Kamiokande detection paper (Hirata et al. 1987 and Hirata et al. 1988) and inferred upper mass limits on neutrino mass (Arnett and Rosner 1987); more recent review on supernova neutrino detection (Scholberg 2012)
• see also at end of the list under "Z ..."

Electron-capture supernovae

• One of the first papers on the topic: Miyaji et al. 1980 (see also Nomoto 1984)
• A more modern investigation: "The Remarkable Deaths of 9-11 Solar Mass Stars" by Woosley and Heger 2015
• The Crab supernova as an electron-capture supernova: Nomoto et al. 1982
• What is the remnant of an ECSNe? Jones et al. 2016

Gamma-ray bursts

• Discovery paper from Vela satellites after declassification of detections: Klebesadel et al. 1973
• General overview of both short- and long-duration gamma-ray bursts: Levan et al. 2016
• Short-duration gamma-ray bursts: review by Berger 2014; final confirmation as NS+NS merger via simultaneous gravitational-wave signal and gamma-ray burst detection Abbott et al. 2017; corresponding optical transients are also known as kilonovae (see below)
• Long-duration gamma-ray bursts and the collapsar model: Woosley 1993

Fast-radio bursts

• The famours "Lorimer" burst (Lorimer et al. 2007), the first detected fast-radio burst
• Still, we do not know what they are, but here is a summary of what we know so far: Petroff et al. 2019 and Cordes and Chatterjee 2019

Kilonovae and r-process

• The general idea: Metzger et al. 2010
• Recent review: Metzger 2019
• First detected kilonova accompanying GRB130603B: Tanvir et al. 2013 and Beger et al. 2013
• For final confirmation of association with NS+NS merger, see gamma-ray burst and gravitational-wave sections.

Luminous-blue variables and supernova impostors

• Recent overview paper: Smith 2017; classic review: Humphreys and Davidson 1994 (see also corresponding section in Smith 2014)
• SN impostors: van Dyke and Matheson 2012 (ask me for a copy of this paper if needed)
• SN2009ip: Mauerhan et al. 2013 and Pastorello et al. 2013
• Eta Carinae and its infamous Great Eruption, interpreted within a stellar-merger scenario: Smith et al. 2018
• A theoretical calculation of unstable stellar envelopes: Jiang et al. 2018 and Jiang et al. 2015
• In general, also see connection to pulsational pair-instability supernovae

Luminous-red novae or gap transients

• Two prototypes: V1309 Sco (Tylenda et al. 2011) and V838 Mon (Bond et al. 2003)
• A potential explanation within common-envelope/star-merger models: Ivanova et al. 2013

Pair-instability supernovae

• Classic references (but you may prefer a good text book or so): Barkat et al. 1967, Rakavy and Shaviv 1967 and Fraley 1968
• Recent papers on (pulsational) pair-instability supernovae including conections to gravitational-wave astronomy and the black-hole mass gap: Woosley 2017, Farmer et al. 2019

Soft-gamma repeater

• An online version of a popular article written for Scientific American: Duncan 1998, 2003
• Key paper lifting the mystery of soft-gamma repeaters: Kouveliotou et al. 1998
• Using soft-gamma repeaters to measure the strongest magnetic field in the Universe: Ibrahim et al. 2002
• (Theoretical models explaining soft-gamma outbrusts and X-ray emission from neutron stars in quiescence: Thompson and Duncan 1995, Thompson and Duncan 1996)

Superluminous supernovae and hypernovae

• Probably some of the most spectacular explosions in the Universe; here are two recent reviews by Moriya et al. 2018 and Gal-Yam 2019
• Rates of rare transients in light of their likely progenitors: Podsiadlowski et al. 2004; a nice illustration of how useful rates can be

Tidal-disruption events

• Classic paper by Lord Martin Rees on tidal disruption of stars by a supermassive black-hole: Rees 1988
• Latest observational results from the ZTF transient factory: van Velzen et al. 2020
• First paper in a series of modern models of tidal-disruption events: Ryu et al. 2020

Type Ia supernovae

• Explosion models (e.g. single- and double-degenerate channels): Hillebrandt and Niemeyer 2000; see also introduction in Diploma Thesis of Sebastian Ohlmann (available upon request)
• Observational clues to the progenitors of Type Ia supernovae by Maoz et al. 2014
• Connection to cosmology and the accelerated expansion of the Universe: see above reference, Goobar and Leibundgut 2011 and maybe corresponding section in Andrew 2011; Nobel-prize-winning discovery papers: Riess et al. 1998 and Perlmutter et al. 1999

Z aka the end of the list

• General overview of how massive single stars end their life: Woosley et al. 2002, Heger et al. 2003

Are you missing a topic?

• Feel free to suggest one and we can most likely make it happen!
• Or maybe you recently found an interesting paper on some transients or explosive phenomena? Again, it may well fit into this seminar!