The case for Magnetar power in SNe Ib/c and SLSNe. Paolo A. Mazzali and LJMU group: Simon PrenCce Chris Ashall and Elena Pian

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1 The case for Magnetar power in SNe Ib/c and SLSNe Paolo A. Mazzali and LJMU group: Simon PrenCce Chris Ashall and Elena Pian

2 Magnetars have been invoked: XRF/SNe: to explain the large Luminosity [i.e. M( 56 Ni)] and Ek for a star with M ZAMS ~20M! GRB/SNe: to juscfy the apparent constancy of SN properces [Ek, M( 56 Ni)] despite the wide diversity of the associated GRBs SLSNe: to explain the large Luminosity ( too much 56 Ni would be required ) ULGRB/SNe: to explain the SN LC and the duracon of the GRB ergs OSU, Corvallis 2

3 1) A magnetar in XRF/SN bl- Ic 2006aj? SN2006aj, a SN Ic-5, dimmer than GRB/SNe M( 56 Ni) ~ 0.2M M ZAMS ~20M Difficult to produce a lot of 56 Ni from a small mass core. Remnant likely a NS Extra energy from Magnetar? (Pian+ 2006, PM+ 2006) ergs OSU, Corvallis 3

4 Classical Magnetar theory: supporcng SN light curves with NS rotaconal energy Late injeccon of energy shocks SN ejecta Prolonged luminosity Steep density profile " slow evolucon of velocices (Kasen & Bildsten 2010, Woosley 2010) Energy input could be anisotropic (jet- like?): MagneCc tower (Uzdensky & MacFadyen 2007) ergs OSU, Corvallis 4

5 Classical Magnetar theory: SN light curves A range of LCs can be obtained, matching many observed SNe, incl. GRB/SNe and SLSN Can match cases where a lot of 56 Ni is required Degeneracy between magnetar and 56 Ni powering (Kasen & Bildsten 2010, Woosley 2010) ergs OSU, Corvallis 5

6 1b) A Magnetar in SN Ib 2005bf? SN 2005bf (Tominaga et al. 2007) showed a bright, late 2nd LC peak Magnetar accvity may have been responsible for rebrightening (Maeda+ 2007) NoCce late appearance of HeI lines ergs OSU, Corvallis 6

7 2) GRB/SN 1998bw: high mass and KE τ LC τ LC κ1/ 2 M 3 / 4 E 1/ 4 KE 52 = 5 10 erg Iwamoto et al ergs OSU, Corvallis 7

8 2) GRB/SNe LCs are caused by 56 Ni Strong nebular Fe lines in nebular spectrum resemble SNe Ia, and tescfy to the large amount of 56 Ni synthesised: if there is Fe at late Cmes it almost certainly comes from 56 Ni decay Oxygen line are broader than Fe lines, indicacng an aspherical explosion (Mazzali et al. 2001) ergs OSU, Corvallis 8

9 Modelling results 2016jca 2016jca SN2016jca was (again) similar to all other GRB/SNe ergs OSU, Corvallis 9

10 GRB/SNe: What powers the SN Ek? Compare energies of GRBs and SNe GRB SN GRB GRB+SN SN Ek always dominates, and it is close to maximum magnetar energy (PM+2014) ergs OSU, Corvallis 10

11 3) What powers SLSN- I light curves? 3 opcons: 56 Ni Magnetar energy CSM interaccon How do we discnguish between 56 Ni and Magnetar energy? Very late observacons can help How much 56 Ni is available? For PISN candidate SN 2007bi Fe emission suggests 3-5 M! of 56 Ni A few other cases when nebular spectra are available (see AJ+2017) Can interaccon be disentangled? SN 2007bi, Gal- Yam, PM, et al ergs OSU, Corvallis 11

12 SLSN- I spectra show non- thermal component peculiar OII lines are result of non- thermal excitacon/ionizacon at high Temp HeI lines appear via same process only later, when Temp is right (lower) Slow evolucon of line velocices due to steep density profile (PM+2016) ergs OSU, Corvallis 12

13 The OII ion OpCcal OII lines come from lower levels with higher excitacon energy than HeI (>22eV). Not thermally excited ExciCng these levels requires strong non- thermal flux, possibly X- rays from impact of magnetar ergs OSU, Corvallis 13

14 ComposiCon otherwise like SNe Ib/c 06D4eu PTF13ajg Most lines are C/O, Interm. Mass or Fe- group elements, as in SNe Ic (He visible late somecmes) (PM+2016) ergs OSU, Corvallis 14

15 Magnetar and 56 Ni can produce similar light curves both at early and late Cmes (too many free parameters) Moriya et al We want to understand what source is accve when ergs OSU, Corvallis 15

16 e.g. SLSN- I 2015bn: 56 Ni or Magnetar? Early LC requires 32M! of 56 Ni!!! (Nicholl et al 2016) Late decay is faster than 56 Co slope, indicacng incomplete γ- ray trapping, addiconal power source at early Cmes ergs OSU, Corvallis 16

17 or both? Spectrum of SN2015bn starts as a SLSN- I, but evolves to resemble GRB/SNe or SN 2007bi at late Cmes (Nicholl+ 2016, Jerkstrand+ 2017) Fiued with ~5M! of 56 Ni this is a minimum 56 Ni mass which must be removed from any magnetar LC model Both 56 Ni and Magnetar energy conversion contribute to LC ergs OSU, Corvallis 17

18 Is the answer in the light curves? courtesy A. de Cia If SLSN- I LCs have a significant contribucon by a magnetar and PISN candidates are purely driven by 56 Ni, expect a larger peak- to- tail contrast for SLSN- I ergs OSU, Corvallis 18

19 InteracCon also contributes: LSQ14mo SN spectra awer peak are too cold for Lum RecCfied spectra are very similar despite change in Lum ergs OSU, Corvallis 19

20 LSQ14mo: decomposicon of LC InteracCon makes a small contribucon to the LC awer maximum (Chen et al. 2017) Awer subtraccon of interaccon contribucon, the rest of the LC could again be due to a combinacon of Magnetar and 56 Ni power ergs OSU, Corvallis 20

21 SLSNe and ULGRBs? Ultra- long (>10 4 s) GRB showed a SN bump (SN2011kl) SN LC intermediate in Lum between GRB/SNe and SLSNe Blue spectrum, consistent with high Ek SLSN (steep ρ(r) ) LC consistent with Magnetar powering (Greiner et al 2015, Nature) ergs OSU, Corvallis 21

22 Velocity evolucon: SNe Ic v. SLSNe HNe reach higher velocices, which decline very quickly in SLSNe moderately high velocity is sustained over a much longer Cme, suggescve of Magnetar powering ULGRB/SLSN has higher vel than other SLSNe ergs OSU, Corvallis 22

23 Comparing SNe Ib/c and SLSNe- I SNe Ib/c: ejected mass correlates with both 56 Ni mass and Ek SLSNe: similar Ek range as SNe Ib/c; may reach larger Mej; Ek and Mej correlate, but Ek/M is typically lower (ULGRB/SN is the excepcon); liule info on M( 56 Ni) (yet) ergs OSU, Corvallis 23

24 Comparing properces M ej (M! ) Ek (10 51 erg) Ek/Mej M ej (M! ) Ek (10 51 erg) SNe Ic- 7,6, ~1 SLSNe- I SNe Ic- 4 (BL) GRB/HNe (SN Ic- 3) ULGRB/SN ULGRB/SNe and SLSN can have He and H (like SNe Ib/c, Iib) all cores of massive stars (binaries?) Highly excited OII (and He I) lines due to non- thermal excitacon GRB/SNe, ULGRB/SNe have the highest Ek, Ek/Mej ULGRB/SNe NOT at massive end of range GRB/SNe driven by 56 Ni, ULGRB/SNe probably not (only). Magnetar powering likely in GRB/HNe, SLSN- I and ULGRB/SNe, but with different Cmescales ergs OSU, Corvallis 24

25 Conclusions The contribucon of a Magnetar seems likely in many situacons (some SNe Ib/c, GRB/SNe, SLSN- I) It may not always follow the same pauern ergs OSU, Corvallis 25

26 A possible scenario SLSN- I are SNe Ib/c. They have similar mass ranges (but SLSN- I may reach larger mass) They produce significant 56 Ni, but not enough to power all the Light Curve: M( 56 Ni) tail < M( 56 Ni) peak (Late) Magnetar power injeccon: boosts Luminosity, extends light curve causes non- thermal effects (OII, HeI lines) leads to slow evolucon of line velocity (steep ejecta density structure) They may also collide with H- poor CSM (and see mass loss, unlike SNe Ib/c) (if CSM is H- rich " SLSNe- II) PISN candidates do not seem to require a Magnetar (smaller peak/tail contrast?) 56 Ni sufficient GRB- HN are massive (M ZAMS ~35-50 M ), stripped stars. They make M( 56 Ni)~0.5M, which powers the Light Curve. GRB are diverse, HN very similar. Constancy of Ek suggests (early) Magnetar power as source of Ek. SLSN- I may be linked to ULGBR larger Ek/M Less massive stars (~ 20 M ) collapsing to NS can cause a SN and an XRF (Early) Magnetar power as source of Ek. M( 56 Ni), Mej, and Ek seem to correlate, but relacon is steeper for SNe Ib/c ergs OSU, Corvallis 26

27 Magnetar parameters? SN2005bf GRB, XRF require rapid energy injeccon, large E/M Higher B ~10 16 G SLSNe powered by interaccon: late injeccon Lower B~ G SLSN- I SN2011kl- GRB XRF/SNe GRB/SNe Awer Metzger ergs OSU, Corvallis 27