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We present a method that derives the dust temperatures and infrared (IR) luminosities of high-redshift galaxies assuming radiation equilibrium in a simple dust and stellar distribution geometry. Using public data from the Atacama Large Millimeter/submillimeter Array (ALMA) archive, we studied dust temperatures assuming a clumpy interstellar medium (ISM) model for high-redshift galaxies, then tested the consistency of our results with those obtained using other methods. We find that a dust distribution model assuming a clumpiness of ${\rm log}\, \xi _{\rm clp}=-1.02\pm 0.41$ may accurately represent the ISM of high-redshift star-forming galaxies. By assuming a value of ξclp, our method enables the derivation of dust temperatures and IR luminosities of high-redshift galaxies from dust continuum fluxes and emission sizes obtained from single-band ALMA observations. To demonstrate the method proposed herein, we determined the dust temperature ($T_{\rm d}=95^{+13}_{-17}\, \rm {K}$) of a z ∼ 8.3 star-forming galaxy, MACS0416-Y1. Because the method only requires a single-band dust observation to derive a dust temperature, it is more easily accessible than multiband observations or high-redshift emission line searches and can be applied to large samples of galaxies in future studies using high-resolution interferometers such as ALMA.

 

Experimental studies on astrophysical reactions involving radioactive isotopes (RI) often accompany technical challenges. Studies on such nuclear reactions have been conducted at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study, the University of Tokyo. We discuss two cases of astrophysical reaction studies at CRIB; one is for the 7 Be+ n reactions which may affect the primordial 7 Li abundance in the Big-Bang nucleosynthesis, and the other is for the 22 Mg( α , p ) reaction relevantin X-raybursts.