ULTRAVIOLET PULSE FROM TYPE IA SUPERNOVAE Yi Cao (Caltech) - PowerPoint PPT Presentation

ULTRAVIOLET PULSE FROM TYPE IA SUPERNOVAE Yi Cao (Caltech) Collaborators: S. R. Kulkarni (Advisor), P . E. Nugent, M. M. Kasliwal, A. Goobar, A. Gal-Yam, and the intermediate Palomar Transient Factory collaboration

X - ray UV ( Kasen 2010 ) 2

SWIFT OBSERVATIONS OF SN2011FE 24.21 24.86 23.22 2nd detection 1st spec upper limit 2011 August 23.69 24.82 24.93 24.17 Explosion Date obj. saved Swift obs. 1st detection (Nugent et al. 2011; Brown et al. 2012) 3

UV OBSERVATIONS OF SNE IA Absolute Magnitude Absolute Magnitude Days Since Explosion ( Milne et al. 2010; Brown et al. 2012a, 2012b ) 4

INTERMEDIATE PALOMAR TRANSIENT FACTORY Primary Science Goal: fast-cadence survey for young & fast transients Discovery Machine: 48-inch Telescope at Palomar Follow-up Machine: Palomar 60-inch (Phot.), Palomar 200-inch (Spec.), Keck (Spec.), Gemini-N (Spec.), NOT (Phot. & Spec.), Swift (UV) Transient Discovery in 15 minutes, Spectroscopy Classification in 1 hour, Swift Observation in a few hours 5

FAST & FURIOUS 1st spec 24.21 24.86 23.22 2nd detection 1st spec upper limit 2011 August 23.69 24.82 24.93 24.17 Explosion Date obj. saved Swift obs. 1st detection obj. saved Swift obs. 6

IPTF YOUNG SNE IA SAMPLE Selection criterion: fainter than -16.5 mag at discovery (within a week of explosion; z<0.07) Sample: 38 young SNe Ia two 91T -like; two 02es-like; two 02cx-like Swift obs: three <1 day, four <2 days, 1 <3 days 7

IPTF14ATG: DISCOVERY redshi fu : 0.021 ( Cao et al. 2015 Nature ) 8

IPTF14ATG: SWIFT LIGHTCURVE Absolute Magnitude Absolute Magnitude Days Since Explosion UV Luminosity: 3 ☓ 10 41 erg/s ( Cao et al. 2015 Nature ) Binary Separation: 70 or 90 Rsun 9

IPTF14ATG: SPECTRAL ENERGY DISTRIBUTION 1e−16 Flux Density F_lambda 2.5 Swi fu /UVOT 2.0 )lux DensiWy ( ergs / s / cm 2 / Å ) 1.5 1.0 Optical Spec. R - band 70 Rsun 0.5 90 Rsun 0.0 1000 2000 3000 4000 5000 6000 7000 8000 9000 WDvelengWh ( Å ) Rest - Frame W avelength ( Cao et al. 2015 Nature ) 10

IPTF14ATG: OPTICAL SPECTRA Black: iPTF14atg 2bserver-)rame WaveOenJWh ( Å ) 4000 5000 6000 7000 8000 9000 Green: SN2002es 0ay 6.96 During UV flare 0ay 15.96 6FaOed )Oux + 2IIseW 0ay 24.46 About 10 days before max 612002es@max Around max -une 3.15 About a week a fu er max 612002es@+1 weeN 0J II Ca II 7i II )e II/III 6 II 6i II C II 2 I Ca II 4000 5000 6000 7000 8000 9000 5esW-)rame WaveOenJWh ( Å ) Rest - Frame W avelength ( Cao et al. 2015 Nature ) 11

IPTF14ATG: OPTICAL LIGHTCURVE r - Band Absolute Magnitude ( SN1991bg: Filippenko et al. 1992; SN2005hk: Phi lm ips et al. 2007; SN2002es: Ganeshalingam et al. 2012; Days Since Peak iPTF14atg: Cao et al. 2015 Nature ) 12

IPTF14ATG: HOST GALAXY Ste lm ar Mass: a few times 10 10 Msun No Star Formation 1e−11 8 7 6 λF λ (ergs s − 1 cm 1 ) 5 4 3 2 1 0 3000 4000 5000 6000 7000 8000 9000 10000 2bserved WaveOengWh ( Å ) Observed W avelength 13

SUMMARY OF IPTF14ATG iPTF14atg is a thermonuclear supernova. We observed a strong and declining UV flare in iPTF14atg within a few days of its explosion. This UV flare is consistent with the supernova-companion interaction signature. This observation is a strong evidence that a companion star exists. The observations of iPTF14atg together with other recent observations strongly suggest that thermonuclear supernovae have multiple origins. 14

IPTF14ATG: NEBULAR SPECTRUM Phase: [Fe II] +210 d [Fe II] [Ca II] [O I] 15

COMPANION COMPOSITION? O I [O I] @ 8000 km/s SN2011fe iPTF14atg around max iPTF14atg @ 210 days 16

IPTF14DPK: SN2002ES-LIKE EVENT Apparent Magnitude Absolute Magnitude Si II @ 8000 km/s Look-back Time (days) 17

DETAILED SIMULATIONS ARE WARRANTED! Cycle23: 3 orbits w/ HST STIS/NUV-MAMA ( Kasen 2010 ) 18

BRANCH FRACTIONS OF DIFFERENT CHANNELS SN Iax SN2002es-like SN Ia-CSM CV (maybe?) SNe Ia Luminosity Function = a SD + (1-a) DD Optical: understood well UV: poorly constrained Super-C Events? (iPTF+Swift; ULTRASAT?) (luminosity, persistent carbon, broad lightcurve, low velocity) 19

IPTF13ASV: A CONNECTION? 6 6 6 6 6 6 6 6 66 6 6 6 6 6 348 uSSHU OiPiW 5A7I5 i+0.7 348 5 5A7I5 U 10 −26 360 J-2.5 5A7I5 z+2.0 360 U 5A7I5 -+5.0 360 i+0.7 5A7I5 ++7.0 127 8-4 5A7I5 Y+3.0 12 127 B-3 6wiIW 8V02-11 −24 −18 127 V-1 6wiIW 8VW2-10 Absolute 0Dgnitude −16 uvm 2 14 −22 −14 ASSHUDnW 0DJniWudH + 2IIVHW AbVROuWH 0DJniWudH + 2IIVHW −12 16 −20 −10 −8 18 −6 −18 −20 0 20 40 60 80 −18 Absolute 0Dgnitude 20 −16 uvw 2 −16 −14 ∆ m 15 =1.0 22 −14 −12 −10 24 −12 −8 −20 0 20 40 60 80 DDys since B-bDnd mDximum 26 −20 −10 0 10 20 30 40 50 0-D-56430.2 (dDyV) Follow the LC width - B-band magnitude - color relation (Cao et al. in prep.) 20

IPTF13ASV: A CONNECTION? 20 i37)13DVv 612003fg 18 612006gz 612007if 16 612009dF 9eloFity ( 10 3 km s − 1 ) 14 12 10 8 6 −15 −10 −5 0 5 10 15 20 DDyV VinFe B-bDnd PDxiPuP (Cao et al. in prep.) 21

CONCLUSION The strong UV flare from iPTF14atg is probably from the supernova- companion collision. More observations and detailed modelings are both needed for better understanding the physics of supernova-companion collision, such as line emissions and viewing angle dependence. Type Ia supernovae probably have multiple channels. In order to determine branch fractions of different channels, better understanding to the luminosity functions of normal events, SD events and DD events is required. 22

QUESTIONS Does oxygen observed in iPTF14atg from its companion star? Does it tell us about the chemical abundance of the companion star? What is the physical difference between SNe Iax and SN2002es- like events? Different types of companion stars? How can we build the luminosity function from the double degenerate channel? 23