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Supernovae Light Curves Powered by Young Magnetars

Supernovae Light Curves Powered by Young Magnetars. The past/current (e.g. ROTSE, SNLS, SDSS, Palomar Transient Factory,Pan-Starrs1) and future (Dark Energy Survey, SkyMapper) supernovae surveys probe large volumes, revealing a diversity of supernovae not previously known.

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Supernovae Light Curves Powered by Young Magnetars

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  1. Supernovae Light Curves Powered by Young Magnetars The past/current (e.g. ROTSE, SNLS, SDSS, Palomar Transient Factory,Pan-Starrs1) and future (Dark Energy Survey, SkyMapper) supernovae surveys probe large volumes, revealing a diversity of supernovae not previously known. We (Kasen & LB 2009; Woosley ‘09) explain very bright (> 1044 erg sec-1) core collapse SNe as caused by the birth of a 2-5 ms neutron star with 1014 G < B < 1015 G.

  2. Exciting times for Supernovae and Transients! Palomar Transient Factory (‘09; R=21, 3000 deg2, 5d) Pan-Starrs1 (‘09; V=24, 50 deg2, 4d)

  3. ROTSE (V=18, 200 deg2) 2005ap had photospheric spectra 2006gy (2006tf as well) had evidence for interaction => IIn (see Smith & McCray ‘07)

  4. 2008es: Lpeak=3x1044 erg sec-1 Gezari et al. 2009 Miller et al. 2009

  5. Comparisons to other SNe x100 Typical core collapse event Rest et al 2009

  6. Quimby’s Survey with ROTSE • Evidence for two classes • Type IIL = bright, no evidence for interaction • Type IIn = bright, clear evidence for interaction • Volume rate uncertain, but < 1% of Core Collapse

  7. Simple Lightcurves (ala Arnett) • Consider an ejected mass M that is expanding at v, so R=vt, and has opacity Kappa • Radiation diffusion time is >R/v=age until a time • But before then the expansion is adiabatic and when radiation-dominated=>

  8. Luminosity Estimate • The luminosity is • During the adiabatic phase, T goes like 1/R, giving • This provides an excellent estimate for the peak luminosity of Type IIP SNe (1042-1043 erg s-1 ) where Ro is large for red giants (Popov ’93 is a particularly nice paper).

  9. Births of Magnetars! • Studies of AXPs and SGRs reveal that ~10% of NSs are born with 1014 G < B < 1015 G. If born spinning at P=10msP10 spin-down will occur in: • To substantially impact lightcurve, want this to occur before diffusion kicks in, requiring • In the range of magnetars (Kasen & L.B. ‘09; Woosley ‘09) !!

  10. Resetting the Entropy • The deposition of spin-down energy resets the interior entropy • Where the available energy is the NS rotation • As long as Ep>Esn(Ro/vtp), the entropy is reset, so don’t need to have Ep~Esn to impact the lightcurve

  11. Hot Bubble Formation Magnetar spin-down time = 1 day Kasen & L.B. ‘09 • Mej=5 M • Esn=1051 ergs • One month

  12. Mej=5 M • Esn=1051 erg • Pi=5 ms • Dashed line is 1 M of 56Ni • Expect to see swept up shell in the photospheric velocity time evolution. Kasen & L.B. ‘09

  13. Peak Luminosity and Duration imply Magnetar Properties Kasen & L.B. ‘09 Mej=20 M Mej=5 M

  14. Radiation Hydrodynamics Examples Kasen & L.B. ‘09

  15. Bright Supernovae powered by Magnetars • We don’t need extreme rotation or B to modify the core collapse event • Maximum radiated luminosity is set by rotation, and some expansion losses, to 1052 ergs. • Events as bright as 2005ap and 2008es should be <<10% of all core collapse events, as they require a fast initial spin. • Many ‘bright’ II L’s may be made this way.. As more moderate spins can still brighten the event.

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