Massive-Star Supernovae as Major Dust Factories Ben E. K. Sugerman, Barbara Ercolano, M. J. Barlow, A. G. G. M. Tielens, Geoffrey C. Clayton, Albert A. Zijlstra, Margaret Meixner, Angela Speck, Tim M. Gledhill, Nino Panagia, Martin Cohen, Karl D. Gordon, Martin Meyer, Joanna Fabbri, Janet. E. Bowey, Douglas L. Welch, Michael W. Regan, Robert C. Kennicutt Jr. Science, 313 (14 July 2006), Reviewed by Koji Wada, 21 Nov. 2006

Abstract Type II Supernova 2003gd in the galaxy NGC 628 Optical & Mid-Infrared observation by Spitzer Space Telescope days after outburst: Mid-IR excesses Increasing optical extinction Asymmetries in the emission line profile (blueshift) Radiative-transfer model ( 3-D Monte Carlo radiative-transfer code: MOCASSIN ) Dust formed within the Supernova ejecta ～ < 0.02 M Massive-star supernovae may be major dust producers! and others

Introduction How to produce interstellar dust in the early universe: Gentle winds of low-mass AGB stars? → too long time Massive stars’ Type II supernovae (SNe) ? → Theoretically possible ( M ), but very low (10 -4 M ) in previous observations (SNe 1987A, 1999em) Difficult to confirm, because…  SNe are rare and far apart  Remnants are too cold (<30K) to distinguish dust cloud (Spitzer’s IR camera : 50 – 500 K ) Type II-P SN 2003gd (progenitor mass of M ) Rare case of cotemporaneous optical and mid-IR observations!

Data in support dust production Mid-IR excess Asymmetric blue-shifted emission lines ※ Dust obscures more emission from receding gas. Increase in optical extinction

1. Mid-IR excess Hubble Spitzer mid-IR 499 days 670 days 678 days, Multiband Imaging Secptrometer 3.6, 4.5, 5.8, 8.0  m 24  m Black body fit (5.8,8.0  480 K, L = 4.6×10 5 L r = 6.8×10 15 cm

2.Asymmetric blue-shifted emission line Asymmetry Dust with an increasing optical depth is located within and expanding sphere of uniform emission. Optical extinction A R < 5 for 521 days

3. Increasing optical extinction (1)  -rays from 56 Co decay Average opacity:  56 = cm 2 /g Column depth:  0 = 7×10 4 g/cm 2 at t 0 = 11.6 days for SN1987A Estimated Extinction

Dust-mass analysis 3-D Monte Carlo radiative-transfer code MOCASSIN Within Spherical, expanding shell with r = r in ～ Y r in  ∝ r -2 illuminating radiation proportional to the dust density Grain size distribution : a -3.5 for a = – 0.05  m Dust composition : 15% amorphous carbon, 85% silicates source L : according to (1) T : constant Dust distribution : “smooth” model & “clumpy” model Spherical clump size r c = (Y r in ) Volume filling factor f c Density contrast  =  c /  Uniformly distributed Rayleigh-Talyor unstable Lower mass limit Upper mass limit

Model results Y = 7, r in = 5×10 15 cm, L = 6.6×10 5 L, T = 5000 K ( f c = 0.02 for clumpy model ) Y = 7, r in = 6.8×10 15 cm, L = 9.2×10 4 L, T = 5000 K ( f c = 0.05 for clumpy model ) 499 days 678 days High !

Interpretation of dust mass clumpy model mass : 2×10 -3 M (499 days) - 2×10 -2 M (678 days) >> analytic estimates 5×10 -4 M (499 days) - 2×10 -3 M (678 days) >> or ~ mega-grains approximation M for SN 1987A, 1999em → should be revisited limited use after clumps become optically thick M (499 days) - 4×10 -4 M (678 days) For smooth dust : 5×10 -3 M (499 days) For clumpy dust :

Discussion & Conclusion Condensation efficiency Mass of refractory elements condensed into dust Mass of refractory elements in ejecta = 0.02 M M = progenitor of SN 2003gd : M solar metallicity assumed < 0.12 close to 0.2 needed for SNe to account for the dust content of high-redshift galaxies ∴ Supernovae play an important role in the production of dust in the early universe.