27–29 Aug 2025
Australian Resources Research Centre (ARRC)
Australia/Perth timezone

Radio selections of high-redshift radio galaxies: The MHz-peaked spectrum population

27 Aug 2025, 15:30
20m
Auditorium (Australian Resources Research Centre (ARRC))

Auditorium

Australian Resources Research Centre (ARRC)

26 Dick Perry Ave, Kensington WA 6151
Presentation Galactic and Extragalactic (GEG)

Description

In an rapidly approaching SKA era, the need to characterise radio sources and their host galaxies accurately has emerged as a non-trivial problem, especially for undetected host galaxies. For this population without clear hosts, overlapping with infrared-faint radio sources (IFRSs), the bottleneck in obtaining redshifts lies in dedicated follow-up at sub-mm or infrared wavelengths using over-subscribed instruments. Given the wealth of sensitive, all-sky observations in the radio, there has to be a better way of determining the redshifts for this IFRS-like population which include the elusive powerful radio galaxies at z>5. Previously using the GLEAM survey, efforts were made to select low-frequency turnover high-redshift radio galaxies by their spectral index and curvature within GLEAM and then filter out by other characteristics and verify with follow-up at optical to sub-mm wavelengths. Two z>=3 radio galaxies that were verified from that pilot study now have LOFAR Low Band Antenna data spanning ~35-65 MHz, complementing GLEAM and opening a window into the MHz-peaked turnovers previously hinted at. We compare the rest-frame turnovers and linear source sizes for these sources at very high redshift with known relations and investigate the MHz-peaked spectrum population of sources that are within the large LOFAR field of view. We explore these as potential candidate high-redshift radio galaxies that can be selected or inferred from broadband radio SEDs that extend to <50 MHz.

Timeslot preferences 10min

Authors

Mr Alexander Hedge (ICRAR/Curtin University) George Heald (SKAO) Jess Broderick (ICRAR/Curtin) Jordan Collier (Australian SKA Regional Centre (AusSRC) / Curtin Institute of Radio Astronomy (CIRA)) Nick Seymour

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