Dust grains play a crucial role on formation and evolution history of stars and galaxies in the early universe. We investigate the formation of dust grains in the ejecta of population III supernovae including pair-instability supernovae which are expected to occur in the early universe, applying a theory of non-steady state nucleation and grain growth. Dust formation calculations are performed for core collapse supernovae with the progenitor mass M pr ranging from 13 to 30 M ⊙ and for pair-instability supernovae with M pr = 170 and 200 M ⊙ . In the calculations, the time evolution of gas temperature in the ejecta, which strongly affects the number density and size of newly formed grains, is calculated by solving the radiative transfer equation taking account of the energy deposition of radio active elements. Two extreme cases are considered for the elemental composition in the ejecta; unmixed and uniformly mixed cases within the He-core, and formation of CO and SiO molecules is assumed to be complete.The results of calculations for core collapse supernovae and pair-instability supernovae are summarized as the followings; in the unmixed ejecta, a variety of grain species condense, reflecting the difference of the elemental composition at the formation site in the ejecta, otherwise only oxide grains condense in the uniformly mixed ejecta. The average size of newly formed grains spans the range

We investigate the evolution of dust that formed at Population III supernova (SN ) explosions and its processing through the collisions with the reverse shocks resulting from the interaction of the SN ejecta with the ambient medium. In particular, we investigate the transport of the shocked dust within the SNR and its effect on the chemical composition, the size distribution, and the total mass of dust surviving in SNRs. We find that the evolution of the reverse shock, and hence its effect on the processing of the dust, depends on the thickness of the envelope retained by the progenitor star. Furthermore, the transport and survival of the dust grains depend on their initial radius, a ini , and composition: for Type II SNRs expanding into the ISM with a density of n H;0 ¼ 1 cm À3 , small grains with a ini P 0:05 m are completely destroyed by sputtering in the postshock flow, while grains with a ini ¼ 0:05Y0:2 m are trapped into the dense shell behind the forward shock. Very large grains of a ini k 0:2 m are ejected into the ISM without decreasing their sizes significantly. We find that the total mass fraction of dust that is destroyed by the reverse shock ranges from 0.2 to 1.0, depending on the energy of the explosion and the density of the ambient ISM. The results of our calculations have significant impact on the abundance pattern of the second-generation stars that form in the dense shell of primordial SNRs.

We performed Spitzer Infrared Spectrograph mapping observations covering nearly the entire extent of the Cassiopeia A supernova remnant (SNR), producing mid-infrared (5.5Y35 m) spectra every 5 00 Y10 00 . Gas lines of Ar, Ne, O, Si, S, and Fe, and dust continua were strong for most positions. We identify three distinct ejecta dust populations based on their continuum shapes. The dominant dust continuum shape exhibits a strong peak at 21 m. A line-free map of 21 m peak dust made from the 19Y23 m range closely resembles the [Ar ii], [O iv], and [Ne ii] ejecta-line maps, implying that dust is freshly formed in the ejecta. Spectral fitting implies the presence of SiO 2 , Mg protosilicates, and FeO grains in these regions. The second dust type exhibits a rising continuum up to 21 m and then flattens thereafter. This ''weak 21 m'' dust is likely composed of Al 2 O 3 and C grains. The third dust continuum shape is featureless with a gently rising spectrum and is likely composed of MgSiO 3 and either Al 2 O 3 or Fe grains. Using the least massive composition for each of the three dust classes yields a total mass of 0.020 M . Using the most massive composition yields a total mass of 0.054 M . The primary uncertainty in the total dust mass stems from the selection of the dust composition necessary for fitting the featureless dust as well as 70 m flux. The freshly formed dust mass derived from Cas A is sufficient from SNe to explain the lower limit on the dust masses in high-redshift galaxies.

We used the Spitzer Space Telescope's Infrared Spectrograph to map nearly the entire extent of Cassiopeia A between 5-40 µm. Using infrared and Chandra X-ray Doppler velocity measurements, along with the locations of optical ejecta beyond the forward shock, we constructed a 3-D model of the remnant. The structure of Cas A can be characterized into a spherical component, a tilted thick disk, and multiple ejecta jets/pistons and optical fast-moving knots all populating the thick disk plane. The Bright Ring in Cas A identifies the intersection between the thick plane/pistons and a roughly spherical reverse shock. The ejecta pistons indicate a radial velocity gradient in the explosion. Some ejecta pistons are bipolar with oppositely-directed flows about the expansion center while some ejecta pistons show no such symmetry. Some ejecta pistons appear to maintain the integrity of the nuclear burning layers while others appear to have punched through the outer layers. The ejecta pistons indicate a radial velocity gradient in the explosion. In 3-D, the Fe jet in the southeast occupies a "hole" in the Si-group emission and does not represent "overturning", as previously thought. Although interaction with the circumstellar medium affects the detailed appearance of the remnant and may affect the visibility of the southeast Fe jet, the bulk of the symmetries and asymmetries in Cas A are intrinsic to the explosion.

We investigate the destruction of dust grains by sputtering in the high-velocity interstellar shocks driven by supernovae (SNe) in the early universe to reveal the dependence of the timescale of dust destruction on the gas density n H;0 in the interstellar medium (ISM ), as well as on the progenitor mass M pr and explosion energy E 51 of SNe. The sputtering yields for the combinations of dust and ion species of interest to us are evaluated by applying the so-called universal relation with a slight modification. The dynamics of dust grains and their destruction by sputtering in shocks are calculated by taking into account the size distribution of each dust species, together with the time evolution of the temperature and density of the gas in spherically symmetric shocks. The results of the calculations show that the efficiency of dust destruction depends not only on the sputtering yield but also on the initial size distribution of each grain species. The efficiency of dust destruction increases with increasing E 51 and /or increasing n H;0 but is almost independent of M pr as long as E 51 is the same. The mass of gas swept up by a shock is an increasing function of E 51 and a decreasing function of n H;0 . Combining these results, we present the approximation formula for the timescale of destruction for each grain species in the early universe as a function of E 51 and n H;0 . This formula is applicable for investigating the evolution of dust grains at the early epoch of the universe with the metallicity of Z P 10 À3 Z . The effects of the cooling processes of gas on the destruction of dust are briefly discussed.