On the abundance of gravitational arcs produced by submillimeter galaxies at radio and submm wavelengths

TL;DR

This study predicts the number of giant gravitational arcs caused by submillimeter galaxies lensed by galaxy clusters at radio and submm wavelengths, aiding future survey planning.

Contribution

It introduces a realistic modeling approach for galaxy clusters and SMGs, incorporating ellipticity, substructures, and various redshift distributions to estimate arc abundance.

Findings

Several hundred submm arcs could be detected with 1 mJy/arcsec$^2$ sensitivity at 850 μm.

Approximately the same number of radio arcs can be detected at 20 μJy/arcsec$^2$ at 1.4 GHz.

Results provide useful data for planning future arc surveys and are compared with previous studies.

Abstract

We predict the abundance of giant gravitational arcs produced by submillimeter galaxies (SMGs) lensed by foreground galaxy clusters, both at radio and submm wavelengths. The galaxy cluster population is modeled in a realistic way with the use of semi-analytic merger trees, while the density profiles of individual deflectors take into account ellipticity and substructures. The adopted typical size of the radio and submm emitting regions of SMGs is based on current radio/CO observations and the FIR-radio correlation. The source redshift distribution has been modeled using three different functions (based on spectroscopic/photometric redshift measurements and a simple evolutionary model) to quantify the effect of a high redshift tail on the number of arcs. The source number counts are compatible with currently available observations, and were suitably distorted to take into account the lensing magnification bias. We present tables and plots for the numbers of radio and submm arcs produced by SMGs as a function of surface brightness, useful for the planning of future surveys aimed at arc statistics studies. They show that e.g., the detection of several hundred submm arcs on the whole sky with a signal-to-noise ratio of at least 5 requires a sensitivity of 1 mJy arcsec$^{-2}$ at $850 \mu$m. Approximately the same number of radio arcs should be detected with the same signal-to-noise ratio with a surface brightness threshold of $20 \mu$Jy arcsec$^{-2}$ at 1.4 GHz. Comparisons of these results with previous work found in the literature are also discussed.