Prospects for Observing Galaxy Spectral Energy Distribution from the Radio to the far-Infrared in the Era of Next-Generation Radio Telescopes

TL;DR

This paper explores the potential of next-generation radio telescopes to observe galaxy spectral energy distributions from the radio to far-infrared up to redshift 20, highlighting detection capabilities for various galaxy types and masses.

Contribution

It presents simulated predictions of galaxy SED observations with upcoming telescopes like SKA and ngVLA, extending to high redshifts and including effects like CMB and radio-IR correlation.

Findings

Massive galaxies (M* > 10^10 M_sun) detectable at all redshifts (0<z<20) in high-frequency bands.

ngVLA can detect galaxies with M* > 10^9 M_sun almost independently of redshift.

SKA low-frequency observations can detect M* > 10^10 M_sun dusty galaxies up to z=5-7.

Abstract

The superb sensitivity and angular resolution of the next-generation radio telescopes with combined frequency coverage of approximately over three orders of magnitude (100 MHz--100 GHz) will sample the radio and far-infrared (FIR) spectral energy distribution (SED) of galaxies and revolutionize the galaxy formation study at the epoch of re-ionization and beyond. We present a prospect of observing the radio--FIR continuum SEDs of galaxies in the redshift of up to $z\approx 20$ based on an ensemble of the simulated `energy balanced' panchromatic SED (from UV to FIR) extended to the radio. For `realistic' populations of UV star-forming galaxies and dusty star-forming galaxies, we simulate their SEDs by accounting for the CMB effect and the radio--IR correlation. The flux density evolution of the UV-bright star-forming galaxies and the dusty star-forming galaxies at the selected observing frequencies covered by the current (ALMA) and next generation (SKA and ngVLA) radio-millimeter telescopes, suggest that massive galaxies (M$_* \gtrsim 10^{10}$M$_{\odot}$) are detectable at any redshift ($0<z<20$) in high frequency ($\nu>90$GHz). In particular, when operating, the ngVLA high-frequency ($\approx 100$ GHz) band is capable of detecting galaxies with M$_* \gtrsim 10^{9}$M$_{\odot}$ almost independently from redshift and the SKA low-frequency observing window ($\lesssim1$ GHz) has sufficient sensitivity to detect M$_* \gtrsim 10^{10}$M$_{\odot}$ dusty star-forming galaxies up to the epoch of reionization ($z=5\sim7$). We also show that the brightness of anomalous microwave emission (AME) in the galaxy SED is insignificant if the galaxies are beyond the local Universe (e.g., $z\gtrsim 0.1$).