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Bayesian Analysis for Characterization of Analogs to High-z Galaxies.

Presentation #219.04D in the session “High Redshift Galaxies”.

Published onJan 11, 2021
Bayesian Analysis for Characterization of Analogs to High-z Galaxies.

In order to understand the physical processes related to galaxy formation and evolution, we must study galaxies in their early stages of evolution, High redshift (z) galaxies. However, detailed observations of galaxies in the early universe are very difficult due to the large distances involved, the faintness, and small angular sizes of the galaxies. Since Low-z galaxies can be studied in greater detail, it is paramount to study local galaxies that can be analogs to those in the high-z universe. This has the potential of allowing a more detailed analysis of the physical processes at work. Therefore, we have selected a sample of nearby star forming galaxies, that exhibit properties believed to characterize high-z galaxies. This local analogs can provide insights into the evolution of the first galaxies. Our sample consist of Blue Compact Dwarf Galaxies, which are characterized by a young stellar population, they are actively forming stars, have low metallicities, and are likely to have star formation histories (SFH) similar to the high-z galaxies. We used the SOFIA telescope’s HAWC+ instrument to study their dust properties and how they are related to the star formation activity. Combining this with ultraviolet, optical, and near-Infrared (NIR) data we derive the Spectral Energy Distribution (SED) from UV to FIR wavelengths. We employ Bayesian Statistics in multi-dimensional parameter-spaces to determine how modified blackbody models characterize the dust emission. We also use the SED fitting package LIGHTNING to determine the star formation rate (SFR) and SFH of the local analogs. Also, we used FIR fine-structure lines to identify the neutral and ionized gas components in these galaxies. The ionized gas is characterized by the [CII] 158 μm and [OIII] 88 μm fine-structure lines observed using the SOFIA/FIFI-LS integral field unit (IFU). These lines are accessible with ALMA for high-z objects and our results for the local analogs can be used to infer the ISM properties of the high-z galaxies. Comparing our low-z galaxies with a small sample of high-z galaxies, observed with ALMA, we find that the ionized ISM of the local analogs resembles that of the high-z galaxies. The overall goal with this project is to characterize the properties of the local galaxies, determine if they are truly young systems.

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