VLBI imaging of high-redshift galaxies and protoclusters at low radio frequencies with the International LOFAR Telescope
Abstract
It is generally known that luminous, ultra-steep spectrum radio sources are preferentially associated with massive galaxies at high redshifts. In this paper, we describe a pilot project directed at such objects to demonstrate the feasibility and importance of using the LOw-Frequency ARray (LOFAR) data to study the most distant massive galaxies undergoing formation and protoclusters. We successfully imaged four high-redshift (z > 2), high-luminosity radio galaxies with sub-arcsecond resolution, at 144 MHz, using the International LOFAR Telescope (ILT). Our targets were 4C 41.17, which we dubbed "the Anthill" galaxy (z = 3.8), as well as B2 0902+34 (z = 3.4), 4C 34.34 (z = 2.4), and 4C 43.15 (z = 2.5). We mapped their low-frequency morphologies and the spatial distributions of their low-frequency spectral indices and then compared these results with the available optical, infrared, and X-ray images. Both for the Anthill at z = 3.8 and B2 0902+34 at z = 3.4, the location of the steepest radio emission coincides with the Lyα-emitting ionized gas halo. Our pilot project demonstrates that thanks to its outstanding sensitivity and high angular resolution at low frequencies, the ILT is a unique facility for studying the co-evolution and interaction of massive galaxies, galaxy clusters, and supermassive black holes in the early Universe.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 2023
- DOI:
- 10.1051/0004-6361/202346320
- arXiv:
- arXiv:2306.00071
- Bibcode:
- 2023A&A...676A..29C
- Keywords:
-
- galaxies: clusters: general;
- galaxies: high-redshift;
- radio continuum: galaxies;
- galaxies: jets;
- galaxies: nuclei;
- galaxies: starburst;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 10 pages, 10 figures, 2 tables