The nature of Lyα blobs:: Supernova-dominated primordial galaxies

We consider a forming galaxy undergoing multitudinous supernova (SN) explosions as a possible model of Lyalpha blobs (LABs). For this purpose, an ultra-high-resolution hydrodynamic simulation is performed using 10243 grid points, where SN remnants are resolved with sufficient accuracy. It is found that multiple SN explosions produce kiloparsec-size expanding hot bubbles, which drive cool, dense shells by strong shock. The colliding high-density cooling shells radiate intensive Lya emission, resulting in a high Lya luminosity of similar to10(43) ergs s(-1), comparable to the observed level in LABs. Also, recently discovered bubbly features in some LABs are quite similar to the structure predicted in the present simulation. Furthermore, the result demonstrates that LABs are representative of evolving primordial galaxies; they could hold direct information on the early chemical enrichment of galaxies, contrary to present-day galaxies that have undergone intense recycling of interstellar matter, thus erasing most of the early chemical history. It turns out that the metal mixing proceeds in a very inhomogeneous fashion, so that there appears a large spread of metallicity, that is, or. Hence, [Fe/H] approximate to 0 to -5 [O/H] approximate to 1 to -4 the early galactic chemical evolution may have proceeded in a different manner from that hitherto considered in one-zone models.