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Recent supernova surveys have unveiled a diverse range of supernovae, revealing fascinating insights into their luminosity and behavior. This study discusses how very bright core-collapse supernovae (greater than (10^{44}) erg/sec) can be powered by the birth of young magnetars—highly magnetic neutron stars. Notable phenomena include Type IIL supernovae, lacking interaction evidence, and Type IIn supernovae, showcasing clear interaction signals. By analyzing light curves from various significant surveys, we can better understand the underlying mechanics of these explosive events and their implications for stellar evolution.
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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.
Exciting times for Supernovae and Transients! Palomar Transient Factory (‘09; R=21, 3000 deg2, 5d) Pan-Starrs1 (‘09; V=24, 50 deg2, 4d)
ROTSE (V=18, 200 deg2) 2005ap had photospheric spectra 2006gy (2006tf as well) had evidence for interaction => IIn (see Smith & McCray ‘07)
2008es: Lpeak=3x1044 erg sec-1 Gezari et al. 2009 Miller et al. 2009
Comparisons to other SNe x100 Typical core collapse event Rest et al 2009
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
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=>
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).
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) !!
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
Hot Bubble Formation Magnetar spin-down time = 1 day Kasen & L.B. ‘09 • Mej=5 M • Esn=1051 ergs • One month
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
Peak Luminosity and Duration imply Magnetar Properties Kasen & L.B. ‘09 Mej=20 M Mej=5 M
Radiation Hydrodynamics Examples Kasen & L.B. ‘09
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.
