Oral Presentation
Study of Star Formation Quenching across Redshift Range of 2 < z < 7 using JWST dan HST Data
Presenter: Novan Saputra Haryana (Bandung Institute of Technology)
Galaxies formed approximately 300 million years after the Big Bang, during the cosmic dawn epoch. Subsequently, they underwent evolution in parallel with the universe's development. This evolutionary process encompasses various aspects, notably the rate of star formation within galaxies. In their early stages, galaxies exhibited a much higher rate of star formation compared to the present epoch. The processes and mechanisms responsible for the subsequent slowdown in star formation rate remain a prominent topic of study in astrophysics. In this research, imaging data from the James Webb Space Telescope (JWST) and the Hubble Space Telescope (HST) spanning the redshift range of 2 < z < 7 will be utilized to examine the demographics of quiescent galaxies across a wide range of redshifts. Additionally, we aim to investigate how the morphological parameters of these galaxies evolve over time. Our goal is to gain insights into the mechanisms and processes responsible for the deceleration of star formation rates within galaxies.
In the analysis, galaxies within the redshift range of 2 < z < 4.5 exhibited the highest number density around log M ~ 10.5, with their number density decreasing with increasing redshift. However, within the redshift range of 2 < z < 2.5, another number density peak was observed at log M ~ 8.75, indicating the presence of numerous quiescent dwarf galaxies at this redshift range. Furthermore, for the redshift range of 4.5 < z < 7, the number density remained relatively constant at ~ 10^-6 Mpc^-3 dex^-1. Unlike the previous redshift range, the number density in this range decreased around log M ~ 10.5.
In addition to the findings mentioned, our analysis reveals intriguing variations in the time between galaxy formation and the quenching phase across different redshift ranges. Notably, galaxies within the redshift range of 5.5 < z < 7 exhibit a remarkably short quenching period, sometimes less than 0.9 Gyr. Furthermore, we observed a correlation between quenching duration and galaxy mass within this redshift range, with lower mass galaxies experiencing a quicker quenching phase compared to their higher mass counterparts. These insights suggest that there are different quenching mechanisms involved between low and high mass galaxies.
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