Star Formation
Galaxies are dynamically bound systems consisting of stars and gas. They grow and accumulate mass by converting their gas into stars (i.e., star formation). Young galaxies with large reservoirs of gas, or those that have recently merged with another galaxy, have high rates of star formation, while older galaxies are quiescent with little or no star formation. To measure the rate of star formation, astronomers observe the UV and optical light originated from newly-born massive stars. They extrapolate the formation rate of all stars from the formation rate of the massive ones, assuming a distribution of stellar masses. A major challenge is that UV and optical radiation easily get absorbed by dust grains inside galaxies. Therefore, to measure the total star formation rate, it is necessary to correct the observed light for dust absorption. I study star formation in galaxies during the peak epoch of star formation activity in the universe, about 10 billion years ago, by observing various star formation rate diagnostics, including ultraviolet, optical emission lines, and infrared.
My papers on this topic:
- The MOSDEF Survey: Calibrating the relationship between Hα star-formation rate and radio continuum luminosity at 1.4 < z < 2.6 PDF
Duncan, K., Shivaei, I., Shapley, A., et al. 2020, MNRAS, 498, 3648 - The MOSDEF Survey: Metallicity Dependence of the PAH Emission at High Redshift and Implications for 24μm-inferred IR Luminosities and Star Formation Rates at z ∼ 2 PDF
Shivaei, I., Reddy, N., Shapley, A., et al., 2017, ApJ, 837, 157
Also featured in: UCR Today, Phys.org, Science Daily, EurekAlert, Space Daily - The MOSDEF Survey: The Strong Agreement Between Hα and UV-to-FIR Star Formation Rates for z ∼ 2 Star-Forming Galaxies PDF
Shivaei, I., Kriek, M., Reddy, N., et al., 2016, ApJL, 820, L23
Also featured in: Astronomy UCR, UCR Today, Keck Observatory, Phys.org, Science Daily, EurekAlert, Space Daily, Astronomy Now - The MOSDEF Survey: Dissecting the Star-Formation Rate vs. Stellar Mass Relation Using Hα and Hβ Emission Lines at z ∼ 2 PDF
Shivaei, I., Reddy, N. A., Shapley, A. E., et al., 2015b, ApJ, 815, 98 - Investigating Hα, UV, and IR Star-formation Rate Diagnostics for a Large Sample of z ∼ 2 Galaxies PDF
Shivaei, I., Reddy, N. A., Steidel, C. C., & Shapley, A. E., 2015a, ApJ, 804, 10