SINGLE VS BINARY STAR PROGENITORS OF TYPE IIb

SINGLE VS BINARY STAR PROGENITORS OF TYPE IIb SNe NIHARIKA SRAVAN, PABLO MARCHANT AND VICKY KALOGERA

TIME DOMAIN BIG DATA ASTRONOMY AND SUPERNOVAE • Plethora of survey projects culminating with the LSST will transform SN science by providing unprecedented insights into supernova: • Progenitors • Environments

TIME SENSITIVITY • Pre-SN variability • Late stage massive star evolution • Stellar interactions • Progenitor detection • + Companions • Light curve and spectral evolution – early detection important! • Progenitor structure • CSM interactions • Remnants • End-products of massive star evolution

TIME SENSITIVITY • Reducing detection, classification and analysis overhead • Need but lack comprehensive database of models in the relevant parameter space

A SYSTEMATIC PARAMETER SPACE STUDY OF SN PROGENITORS • My work! • Focus: Stripped Envelope Supernovae

STRIPPED ENVELOPE (SE) SUPERNOVAE H He Type II Core STRIP! SUPERNOVA H He SE SNe (Types IIb, Ic) Core He SUPERNOVA

STRIPPED ENVELOPE SUPERNOVAE MECHANISMS DOMINATING STRIPPING Important to understanding: • stellar winds • close binary interactions in massive star evolution Single Star Progenitors Stellar Winds Binary Star Progenitors Close Binary Interactions

TEST CASE: TYPE IIb SUPERNOVAE

TYPE IIb SUPERNOVAE H He Type II Core 99 d SN 2011 dh 202 d H He Type IIb Core SUPERNOVA Jerkstrand et al. , 2015 time STRIP! SUPERNOVA

• Abundant • ~ 11 -12% a, b of all core-collapse SNe • 30 -40% a, b of all SE SNe Luminosity (L☉) OVERVIEW OF TYPE IIb SNe Progenitor Observations Light Curves Luminosity Hydrogen envelope mass • log 10(L/L☉) = 4. 72 – 5. 4 • 0. 01 – 0. 5 M☉ • Five with detected progenitors • Only stripped envelope SN progenitor with detected binary companion Effective Temperature • log 10(Teff/K) = 3. 58 – 3. 8 Helium core mass • 2 – 6 M☉ Teff (K) a Li Type IIb b Smith et al, 2011

WHAT ARE THE PROGENITORS OF TYPE IIb SNe? Parameter search space • Single star models*: • • Type IIb M/M☉ = 10 – 80 Binary star models*: • M 1/M☉= 10 – 18 • M 2/M☉= 6 – M 1 • log 10(Porb /d) = 0. 0 – 4. 0 • Conservative and non-conservative MT *solar metallicity, non-rotating

PHYSICAL CONSTRAINTS TO MATCH FOR EXPLAINING TYPE IIb SN PROGENITOR OBSERVATIONS Progenitor Properties HYDROGEN ENVELOPE MASS • 0. 01 – 0. 5 M☉ HELIUM CORE MASS • 2 – 6 M☉ LUMINOSITY • log 10(L/L☉) = 4. 72 – 5. 4 EFFECTIVE TEMPERATURE Type IIb • log 10(Teff/K) = 3. 58 – 3. 8

CAN SINGLE STARS BE TYPE IIb SN PROGENITORS? Helium core mass Models with residual Hydrogen envelope mass 0. 01 – 0. 5 M☉ Observations Models Sravan et al. , in prep Observations NO Type IIb Luminosity and Teff

CAN BINARY STARS BE TYPE IIb SN PROGENITORS? • Parameter space occupied by binary star models reaching core-collapse with 0. 01 – 0. 5 M☉ residual Hydrogen envelope Type IIb Sravan et al. , in prep

CAN BINARY STARS BE TYPE IIb SN PROGENITORS? Helium core mass Observations Models with residual Hydrogen envelope mass 0. 01 – 0. 5 M☉ Sravan et al. , in prep Models Observations Models YES! Type IIb Luminosity and Teff

SUMMARY • We find solar-metallicity, non-rotating single stars cannot be Type IIb progenitors • Solar-metallicity, non-rotating binary stars can be Type IIb progenitors These systems have: • Mass ratios > 0. 6 • 3. 2 < log 10(Porb, i) < 3. 6 • Companion luminosity: 4 < log 10(L/L☉)< 4. 8 • Predicted rate ~ 1% of all CC SNe

FUTURE WORK • Complete parameter space: • single star rotating models • binary star models Mprim > 20 M☉ • Study light curves from IIb progenitor models

THANK YOU! 18