For the past few years, we have seen significant progresses of studies on local dwarf galaxies with M*~10^4-10^8 M_sun that are thought to be galaxies in their early formation phase. Observations have shown that local dwarf galaxies have a highly ionized interstellar medium (ISM) with strong HeII emission. Such ISM conditions cannot be explained by stellar synthesis models, even when binaries producing high-energy ionizing photons are considered. Dwarf galaxies are characterized by energy-driven outflows. Dynamical studies reveal that some dwarfs do not show clear evidence of a dark matter halo. The physical properties and ISM conditions of local dwarf galaxies resemble those of high-redshift star-forming galaxies. Local dwarfs might therefore be useful analogs to investigate the formation of the first galaxies at the epoch of reionization (EoR) and beyond, i.e. z~10-20, that will be probed by the forthcoming JWST programs.
During this SAZERAC SIPS we will focus on discussing local dwarf galaxies with both an observational and theoretical perspective to clarify how they can help us understand the early formation of high-redshift galaxies in the JWST era. Now multiple HST/COS surveys are targeting Lyman continuum, Lya, CIV1549, HeII1640, and CIII]1909 emission of local-dwarf galaxies in the UV. These spectroscopic features will be studied with JWST for the high-z galaxies with good sensitivity for the first time. Ground-based large-area data, such as those taken by SDSS and Subaru programs, pinpoint premature dwarf galaxies with a low metallicity down to ~0.01 Z_sun at z < 0.1. These extreme emission-line dwarf galaxies are more common at high redshift, and studies describing the number density, environment, and evolution of the population over cosmic time will be also discussed in this conference, building a bridge between the local samples and EoR galaxies.
Deep integral-field spectroscopy with VLT/MUSE and Keck/KCWI reveal dynamic processes with spatial distributions of metal abundance, ionization state, and outflow. Similar observations of high-redshift galaxies will soon be possible thanks to JWST. Numerical simulations have predicted that local low-mass dwarfs resume star-formation that was suppressed at the end of the EoR via heating of UV background radiation. However, no clear observational evidence is known so far. Additionally, theoretical studies are exploring physical origins of the high ionization states of local-dwarf galaxies, and suggesting various possibilities such as the existence of high-mass X-ray binaries and metal poor AGN. In this conference we will discuss how these theoretical studies could shed light on the formation of the first galaxies at the EoR and beyond.
Abstracts submission has now closed but you can still register to watch the meeting: please fill in the form here. Questions and discussions among participants will be encouraged on a dedicated official Slack channel.
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