SN1987A before(right) and during the explosion. Supernova Explosion. Qingling Ni

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1 SN1987A before(right) and during the explosion Supernova Explosion Qingling Ni

2 Overview Core-Collapse supernova (including Type II supernova) -Mechanism: collapse+rebound Type Ia supernova -Mechanism: accrete+ignite possible progenitor models observational clues for progenitors

3 Core Collapse supernova For white dwarf creates by a star more massive than 8M Gravity VS electron degeneracy pressure Relativistic gas easily compressed by gravity, until reaching nuclear density Rebound: generating shock litters freshly synthesized heavy elements and leaves a neutron star (or a black hole)

4 Core-Collapse Supernova Origin of Elements Fusion: Onion-skin structure Fusion is exothermic only for the assembly of lighter elements into elements up to the iron group Post-processing

5 Core-Collapse Supernova Mechanism for the shock Simple Bounce and rebound model? Through neutrino energy losses and nuclear breakup: Shock stalls between a radius of 100 and 200 km into a quasistationary accretion shock Neutrinos: Reviving explosion Neutrinos diffuse to escape in seconds Mantle heated by the absorption of a fraction of the escaping neutrino in the gain region Accretion pressure(subsiding) VS Heat from neutrinos : Explode!

6 Core-Collapse Supernova source of γ ray burst Observational coincidences GRB970228: power-law decay expected in the relativistic blast model and can be interpreted as a superposition of classic power-law afterglows with supernova light curves. GRB980425: type Ic supernova, SN1998bw, that exploded in a nearby galaxy Some supernova may be able to spawn a gamma ray burst and its early afterglows, followed by supernova explosion

7 Type Ia Supernova For by low-mass stars in binary system Transfer mass from companion to reach the Chandrasekhar mass thermonuclear incineration Nuclear energy released: The gravitational binding energy: Ejecta Velocity

8 Type Ia Supernova Revealing the geometry of the universe A Hubble diagram depicting the calibrated peak blue brightness L of the collection of type Ia supernovae discovered and studied by the Supernova Cosmology project. A plot of Supernova Team using their type Ia supernova data. The Universe will expand forever and to be accelerating. H Age: 14.5 Gyr

9 Type Ia Supernova Progenitor Problem SD model VS DD model Single-degenerate model accretion from a non-degenerate secondary(a main sequence star, a helium star, or a red giant Accretion range Centered around: resembling supersoft X-ray sources the effi accretion mode is limited

10 Type Ia Supernova Progenitor Problem SD model VS DD model Double-degenerate model the more-massive WD tidally disrupts and accretes lower-mass WD off-center ignition accretion-induced collapse?

11 Type Ia Supernova Progenitor Problem SD model VS DD model The possibility of other models: Collisional DD model(triple system?) Double denotations model Super Chandrasekhar-mass model (rotation-supported against collapse and ignition) The calculation of binary population synthesis (BPS) together with observational clues DD model: not an underdog anymore

12 Observational clues for Type Ia Supernova Progenitors Clues from potential progenitor populations SD model progenitors: Progenitor Galactic population of recurrent novae: ~300 VS number of systems needed for the SN Ia rate:~3300 Supersoft X-ray sources: <1% of the WD s growth time spent in this phase DD model progenitors: Total merger rate 1 10 BPS calculation, is same with the SN Ia rate.

13 Observational clues for Type Ia Supernova Progenitors Pre-explosion evidence Li et al. (2011a) SN 2011fe: setting the preexplosion limit SD origin: no red giant and helium-star donors, bright supersoft X-ray sources; allow mainsequence and sub-giant SD donors, and faint supersoft sources DD origin: all survived

14 Observational clues for Type Ia Supernova Progenitors During the SN event bloom et al. (2012):Early light curve puts

15 Observational clues for Type Ia Supernova Progenitors During the SN event Margutti et al. (2012) Chomiuk et al. (2012b)

16 Observational clues for Type Ia Supernova Progenitors Post-explosion evidence in SN remnants No obvious donor in the SD scenario has been detected in strict limits Tycho s SN of 1572 SN1006 SNR : L SNR Not likely to have wind regulation in SD scenario according to h models of remnants Composite HST/Chandra image, in B, V, I, Hα, and X-rays, of the ~ Ia remnant in the LMC

17 Observational clues for Type Ia Supernova Progenitors Delay-time distribution Delay time: time between star formation and SN Ia explosio Nelemans, Toonen & Bours (2013): Obeserved versus theoretical delay time distribution BPS calculations of DD model fits more with data

18 Type Ia Supernova Progenitors Problem Future Outlook Theoretical side: SD model DD model: the process of ignition in DD mergers Observational side: Gaia Gamma ray observations Space-based gravitational wave interferometer

19 Core collapse supernova: Summary Onion-skin structure; Relativistic gas being compressed by gravity, reaching nuclear density; Shock generated through rebounding and revived through the absorption of neutrinos Type Ia supernova Transfer mass from companion to reach the Chandrasekhar mass a strong tool for cosmology Progenitors long in doubt: The observations suggests that, among the various models, only DD progenitors are not ruled out