LiveBlogging the IPMU supernova workshop: Mario Hamuy

Millennium Center for Supernova Science
What are they doing?: Refining distance indicators. Understanding SN physics. Nearby Supernova Search using robotic telescopes. Carry out a follow-up program.
CHASE: the supernova search. 6 40cm telescopes (4 working). 10% time... Sample about 1000 nearby galaxies, sampled every ~4 nights.
Oh look, they found a SN last night. 2 in 2007, 24 in 2008. Roughly 2 per month.
Buying their own telescope... 50 cm... Increase discovery rate... and or follow-up.
Follow-up... teamed up with Carnegie Supernova Project.
Yikes. CSP is killing us at LT.
104 Type Ia’s. They are doing very well. Hubble diagram.... sigma = 0.13-10.17 Using optical. Adding J reduces to 0.12
Hmmm.... Must rethink LT.
Rv low for both type Ia and type II SNe.
A type II “hypernova”? SN 2003bg... SN 2002gh. What the hell is that?

LiveBlogging the IPMU supernova workshop: Itsuki Sakon

“Near- to Mid-Infrared observation of supernovae with AKARI/IRC”

AKARI. New IR Satellite. 70 cm telescope. IRC, near to mid IR. FIS for far IR. Launched Feb 22, 2006. Warm mission: 2008 June. NIR 2-5 micron imag & Spec.

An all sky survey... Covered 94% of the sky. Ishihara 08.
Pointed observations: 10 min integration. (Short!) Accepting proposals for warm missions. Roughly 20 micro Jy for NIR, and 100 for MIR... Lower in warm mode...
Spectra! 1.8 micron to 5.5 micron at 0.06 Prisim
2.5-5 at 0.0097 for grism. 0.1,0.2 mJy sensitivity.

06jc results: Peculiar Ib. Continuum excess, fading of red side of lines and increase of extinction. Spectra... Yikes source confusion. Spectrum sits across galaxy.
Probably not silicates... (Too bright) Probably amorphous carbon. 2 component model gives better fit. Perhaps pre-existing dust. Mention of Mattila et al 2008.

NEWSY.... Spectral Templates for nearby galaxies for subtractions...

LiveBlogging the IPMU supernova workshop: Nozomu Tominaga

Light curves of Type II Supernovae: Metallicity Dependencies.
“Discussion is Welcome... And conclusions may change after discussion”. Cute.
First talk by a member of the Subaru generation. Lots of young energetic Japanese astronomers here.
Light curves of Type IIs... characterized by the envelope mass and pre-sn radius... also metallicity. Type I: by Mej, M Ni, and E. LC Plateu, brighter and longer for larger Menv....
Difference btw SN Ibc and SN II? MS mass? Single vs Binary? Metallicity? Mass loss uncertain.. Can these be constrained just with MColor LCs? Stella, radn hydrocode from Blinnikov et al. Type IIs have weak metal lines and close to BB. Large PreSN radius so Rad Trans important...
Using code, explore effects of Energy, MS mass, and Metallicity. Progenitor models from Umeda & Nomoto 2005, Explosions 1,5,10,20 FOE. MS mass, 13,15, 18,20,25,30, Metallicity ... missed it...

Higher energy makes shorter and brighter plateaus.
Larger MS mass makes brighter and longer plateaus. Some discussion of the difference between input KE and actual result KE. Plateaus seem long... all are above 100 d which is near the long end of observations... Perhaps KE is too low?
Metallicity... Zero metallicity star is compact, but the rest have similar structures... Envelope mass has complicated relation to metallicity... some discussion between those responsible for the input models... Metallicity results: zero metallicity star has 87A-like light curve, Otherwise the trend is relativity weak for metallicities. However colors change significantly. Higher metallicity sne are redder. Higher metallicity means larger photospheric radii (larger opacity). Same structure, but larger radius so cooler.

Looking at shock breakout. For larger PreSN radius, longer shock breakout, higher total energy, but fainter and cooler.
Energy: Higher energies are brighter and bluer.
MS Mass: Larger mass makes the peak longer and color redder. Lifan asks where is Ly Alpha.. Its ionized. Very hot (300K +)
Metallicity: All similar except metal free, spectra very similar as well.. (not surprising if ionization is very high and opacity low.)

Sensitivity for seeing these things in S-Cam on Subaru. 30 Msun at z=2 possible in 1 hr? NIR on JWST, 10 ks observations, 10 sigma.... Discussion of how to find these things...

LiveBlogging the IPMU supernova workshop: Sergi Blinnikov

Radiative Shocks vs Other Models of the Most Luminous SNe

        First messengers from core collapse: Neutrinos? Gravitational Waves, Radio Waves? (Early radio pulse?) (Bisnovati-Kogan et al, 1988 for SN 1987A) This speculation about a neutrino induced prompt radio pulse is kicking up a fair bit of discussion.
        Shocks inside SNe. Computation of shock breakout. Optical depth ~10. Termination of shock acceleration... missed that... Ah. a plot of optical depth near shock breakout...
        Formation of a thin shell at the outside. Chevalier and so on... shock interaction... Cold dense shell... Model for bright SNe: Chugai et al. 04, Woosley et al 07. Cold dense shell on the inside of large CS envelope. Shock cannot breakout completely for several years.... Dense shell is not adiabatic but nearly isothermal... 4 orders of magnitude in density jump...
Comparison to other models Radioactive needs very large Ni mass. 64FOE... Diffusion... Atmospheric....
        06gy... 1 FOE in light. 2 orders of mag more than normal SN II. If radioactive, need large energy. Why xray low if shock.... missed some more...Something went by about entropy. Yikes, he’s just blowing past lots of stuff.
        Back to the McCray diffusion model. Some referencing old Russian papers... Diffusion lengths are really much shorter... can’t make it fit.
        Back to shocks.... Chugai again... Oh dear, Dessart & Hillier, et al.... density profiles not self consistent. Missed limb brightening effect due to shell.... Photospheric radius wrong...
        Huge shells from PP instability producing large pulsations in ~100 Msun stars.
        Conclusions: He prefers radiating shocks for energy production... poo-poos pure diffusion and pure atmospheric models...
        Discussion... X-rays are self absorbed until later times.... Lifan complains about 1D vs 3D...

LiveBlogging the IPMU supernova workshop: Peter Nugent

11:25 Now we have Peter Nugent: SNe 1999as & 2007bi. Twin Pair Production SNe?

Bias in SN Searches: You find the kinds of things you’re looking for. KAIT, Zwicky & Amateurs: Targeting big galaxies. High-z searches. SNf and SDSS: Rolling searches.

        SN 1999as: Search to find low z SNe using similar methods to high-z searches. ie. big fields not bright galaxies. SN 1999as found by NEAT. Something that showed up with nothing there.

        Spectrum looks like a type Ibc. Some narrow features. Redshift of .1 Mag at max =-21.
Almost no evolution in spectral features over 25-55 days. Narrow features 1000 km/s wide at 10,000 km/s: Detached shell. Fe II and Ti II.

        LC models: 5M Ni, Mtot = 50M, KE = 50 FOE.

        Host spectrum: Metallicity < 1/3 Solar. Mv = -17.8

        Other SNe like SN 1999as?: SN 2001bb Mabs = -17. Dropped like a rock. Similar spectrum with narrow Fe & Ti features.

        No event like 99as, until....

        SN factory: 10,000 images per night. 10% have 5sigma detections. Automated rejection tree knocks this down to 100 per night. Good at finding Type Ias.

        Finding lots of Type Ias in low luminosity and low metallicity galaxies.

        Deep Sky: 9 Years of data on the sky. Useful targeting aid. Allows the removal of distant AGN and variable stars.

        SN 2007bi. Host Mg=-16.4 @ z=.127 Mv = -20.5. Like 99as. Slow decay LC at early times (again like 99as).

        Prediscovery -50 d. (Would have been thrown out if known)

        Why PPSN? Large 56Ni. Too much for “standard” mechanism. Large total mass. Large KE. Low Metallicy environment. What else could it be: CSM, but no smooth continuum and no narrow hydrogen....

        Conclusions: What you find is what you get. These things have slow light curves and would get thrown out of Ia searches.

        Discussion: Lots of questions about CSM interaction. Way to use interaction to power these things? What about lack of He in the spectra. Decay rate for 07bi consistent with Co decay... For a year!

        Plug for the Palomar Transient Search. Coming in March.

        Also. Both super Chandra SNe are in low metallicy galaxies.

LiveBlogging the IMPU Supernova Workshop: What is this?

So I’m attending a workshop on supernovae at IPMU in Kashiwa, Japan, and instead of just passively watching, I thought I’d try and take notes on the talks in real time. So what you’re seeing here are my notes (pretty sketchy, sorry) of the meeting. I may also drop in some commentary if I feel inspired. Or perhaps I’ll just get tired of it and stop at some point. Time will tell.

One note already. The Mac fraction seems suspiciously large in the astronomy world, at least as far as laptops are concerned. Well above the rate they are seen in the wild. Peter Nugent is up next.

Of course, you can feel free to ignore all of this cryptic astrophysics nonsense.

LiveBlogging the IPMU Supernova meeting: Ken Nomoto

10:20
And we’re off. Ken Nomoto is going to tell us about the “Supernova-Progenitor Connection”.
        Supernova density profile is highly dependent on the progenitor: Low mass have steeper envelopes.
        8-10 Msun stars: Super AGB stars (Mcore > 1.07) ONeMg core collapse due to electron capture. At above 10.4 Msun, Ne burning is ignited (Ne flash) in degenerate core... leading to mass ejections? (Nomoto 1984) Origin of very bright type II supernovae (Woosley)?
        Below 10 Msun: no Ne burning. Degenerate ONeMg core. MONeMg=1.35 Msun. Steep density gradient outside degenerate core.
        Electron Capture on ONeMg core: (Miyaji et al. 1980) Electron capture reduces the degenerate electron gas support and leads to collapse. (Picture of Mg lizard eating the e-)
        Kitaura et al. (2006) 9Msun star. Neutrino heating causes weak explosion in spherical model (.1FOE). Mej=0.014 Msun. Overproduction of 90Zr (Hoffman et al 2008).
        Constraints on Ye (Wanajo et al 2008).
        Pastorello et al 2008: Ultra-Faint SNe IIn? M85 OT2006-1 2008S. Also 1997bs, 1999br, etc. (Botticella et al. 2008, Prieto et al. 2008).

        10-90 (60)Msun stars: Fe Core Collapse... Asphericity. Nomoto et al 06, Limongi et al 00: general agreement in heavy element production. Also Heger &Woosley 08, Umeda & Nomoto 02, Tominaga 08. Mixing and asymmetry. All differ significantly to observations of metal poor stars. (Cayrel et al 2004). Agreement improved by high energy (10 FOE) asymmetric (Mixed) explosion, Tominaga et al 2006). Jet induced nucleosynthesis (Tominaga et al again). Tominaga et al 2007

        Main sequence mass vs Kinetic Energy. Fork diagram. Hypernova branch and Faint SN branch. Also MS mass vs Ni Mass. Again a forked diagram. Ib’s at the branching point?
        Hamuy 2003: Trend in Mej & MNi vs E (FOE).

        Wolf-Rayet connetion? Ib,Ic. Mass loss vs Angular Momentum loss. ?

        SN 2008D. Ib’s bridging the gap between Hypernovae and normal SNe?

        90-140 Msun stars: Instability in the core. Oscillations leading to Fe Core collapse. (Umeda & Nomoto) (Near e+e- instability region). 30FOE, 5Msun 56Ni (!)

        140-300 Msun stars: Pair Production SNe. Don’t match metal poor stars? Interesting.
        SN 2006gy. (13 Msun Ni mass!?!) CSM Interaction? 64FOE, 15M Ni? Light curve not like Pair production supernovae (Fast, not slow).