Rapid formation of large dust grains in the luminous supernova 2010jl

Abstract

The origin of dust in galaxies is still a mystery (1, 2, 3, 4). The majority of the refractory elements are produced in supernova explosions but it is unclear how and where dust grains condense and grow, and how they avoid destruction in the harsh environments of star-forming 3 Figure 3 shows the resulting confidence interval for the two parameters a max and α around the best fit values of a min = 0.001 µm, a max = 4.2 µm and α = 3.6. It is evident that only size distributions extending to grain radii that are significantly larger than that of MW interstellar medium (21, 22) dust ( 0.25 µm) can reproduce the supernova extinction curve (Figure 2). The 2 σ lower limit on the maximum grain size is a max > 0.7 µm. We cannot perform a similar analysis of the late epoch because the intrinsic line profile at this epoch is unknown and likely highly affected by extinction (13). However, we note that the blueshift velocities change only marginally with wavelength (Extended Data Figure 6), suggestive of large grains also at this epoch. Figure 4 illustrates the continuous build-up of dust as a function of time. The increasing attenuation of the lines is accompanied by increasing emission in the near-infrared (NIR) spectra, from a slight excess over a supernova blackbody fit at early times to total dominance at the late epoch. We fitted the spectra with black bodies which for the NIR excess yield a constant blackbody radius of (1.0 ± 0.2) × 10 16 cm at the early epochs, and a temperature that declines from ∼ 2,300 K to ∼ 1,600 K from day 26 onwards. At the late epoch, we obtain a black-body radius of (5.7 ± 0.2) × 10 16 cm and a temperature of ∼ 1,100 K. The high temperatures detected at the early epochs suggest that the NIR excess is due to thermal emission from carbonaceous dust, rather than silicate dust, which has a lower condensation temperature of ∼ 1, 500 K (1). The high temperatures rule out suggestions that the NIR emission is due to pre-existing dust or a dust echo (11) (Figure 1), the accelerated dust formation occurring at later times ( Figure 4) and at larger radius is possibly facilitated by the bulk ejecta material, which travels on average at a velocity of ∼ 7, 500 km s −1 at early epochs (Extended Data Figure 4).Our detection of large grains soon after the supernova explosion suggests a remarkably rapid and efficient mechanism for dust nucleation and growth. The underlying physics is poorly understood but may involve a two-stage process governed by early dust formation in a cool, dense shell, 5 followed by accelerated dust formation involving ejecta material. For Type IIP supernovae, the growth of dust grains can be sustained up to 5 years past explosion (25). The dense CSM around Type IIn supernovae may provide conditions to facilitate dust growth beyond that. The process appears generic, in that other Type IIn supernovae like SN 1995N, SN 1998S, SN 2005ip, and SN 2006jd exhibited similar observed NIR properties (8, 10, 26, 27) and growing dust masses, consistent with the trend revealed here for SN 2010...

Interstellar Extinction

“…According to Figure 9: The distribution of the spatial density of dust as a function of dust particle radius in the shell of a supernova (dot-dashed curve), in interstellar medium with carbon and silicate dust (smooth black curve), in interstellar medium with ice dust (different normalization) (black dashed curve), and inside the solar system according to data from the Ulysses spacecraft (grey smooth curve), according to data from the New Horizons spacecraft (square with an indication of uncertainty), and according to data from the Pioneer spacecraft (diamonds with an indication of uncertainty). the data of Gall, et al (2014), the dust from the supernovae SN 1995N, SN 1998S, SN 2005ip and SN2006jd had roughly the same characteristics. Scicluna, et al (2015), also found coarse dust using the SPHERE equipment at the VLT telescope in an analysis of gas-dust shell shed by the supergiant VY Canis Majoris.…”

“…(1) to normalize the size distribution of dust particles produced by the supernova SN 2010jl according to Gall, et al (2014). This can be regarded as the size distribution of dust particles in the locations where they are produced and is plotted as the dot-dashed curve of Fig.…”

“…Relying on the results of Dwek, et al, (2007), they concluded that, in this case, supernovae with a collapsing core are the dominant sources of dust in the medium of galaxies with any red shifts. Gall, et al (2014), have analyzed the properties of the dense medium surrounding the supernova SN 2010jl a few days after an explosion. They concluded that dust particles with radii from 0.001 to 4.2 µm appeared in this medium, with most larger than 1 µm (80% of the mass of the dust is contained in grains with radii greater than 0.1 µm).…”

The Interplay Between Chemistry and Nucleation in the Formation of Carbonaceous Dust in Supernova Ejecta

“…Despite the more gradual formation, however, we are not able to fully reproduce the observational results that require an even more gradual and continuous dust formation in the ejecta, with dust appearing as early as two months after core-collapse and gradually increasing for a few years to a decade (Gall et al 2014), eventually leading to a highly efficient condensation of a sizable fraction of a solar mass (Indebetouw et al 2014). The addition of non-carbonaceous dust chemistry (e.g., Sarangi & Cherchneff 2015) and/or a fully threedimensional calculation (D. Lazzati & D. Fallest 2015, in preparation) can ameliorate the discrepancy.…”

“…The most obvious is the fact that we consider only carbonaceous dust, while more species are known to condensate in supernova explosions. Condensation of silicates and other dust species can begin earlier and explain the early dust formation observed in some SNe (Wooden et al 1993;Gall et al 2014;Sarangi & Cherchneff 2015). On a more fundamental level, our code still assumes a constant sticking coefficient λ=1, a spherical shape for the forming grains, down to the smallest sizes, and the capillary approximation of a size-independent surface energy for any cluster with i>2.…”