Very long baseline interferometry observations of the high-redshift blazar candidate J0141–5427

Active galactic nuclei (AGN) have been observed as far as redshift. They are crucial in investigating the early Universe as well as the growth of supermassive black holes at their centres. Radio-loud AGN with their jets seen at a small viewing angle are called blazars and show relativistic boosting of their emission. Thus, their apparently...

Analysing the Performance of SPLITTER: A Noise Removal Algorithm for DESHIMA 2.0

More insight has been gathered on the performance of the SPLITTER (Stationary spectrum Plus Low-rank Iterative TransmiTtance EstimatoR) algorithm as developed by Brackenhoff for denoising data gathered from observations of high-redshift galaxies. By using matrix decomposition to split the gathered data into a low-rank atmosphere matrix and a...

PRUSSIC: I. A JVLA survey of HCN, HCO+, and HNC (1–0) emission in z 3 dusty galaxies: Low dense-gas fractions in high-redshift star-forming galaxies

Dusty star-forming galaxies (DSFGs) at redshift z ≥ 1 are among the most vigorously star-forming galaxies in the Universe. However, their dense (≥10 ⁵cm ^-3) gas phase - typically traced by HCN(1-0) - remains almost entirely unexplored: only two DSFGs have been detected in HCN(1-0) to date. We present the results of a...

NOEMA confirmation of an optically dark ALMA-AzTEC submillimetre galaxy at z = 5.24: A late-stage starburst prior to quenching

We have obtained deep 1 and 3 mm spectral-line scans towards a candidate z ≳ 5 ALMA-identified AzTEC submillimetre galaxy (SMG) in the Subaru/XMM-Newton Deep Field (or UKIDSS UDS), ASXDF1100.053.1, using the NOrthern Extended Millimeter Array (NOEMA), aiming to obtain its spectroscopic redshift. ASXDF1100.053.1 is an unlensed optically dark...

VLBI observations of VIK J2318-3113, a quasar at z = 6.44

The nature of jets in active galactic nuclei (AGNs) in the early Universe and their feedback to the host galaxy remains a highly topical question. Observations of the radio structure of high-redshift AGNs enabled by very long baseline interferometry (VLBI) provide indispensable input into studies of their properties and role in the galaxies'...

Deshima 2.0: Rapid Redshift Surveys and Multi-line Spectroscopy of Dusty Galaxies

We present a feasibility study for the high-redshift galaxy part of the Science Verification Campaign with the 220–440 GHz deshima 2.0 integrated superconducting spectrometer on the ASTE telescope. The first version of the deshima 2.0 chip has been recently manufactured and tested in the lab. Based on these realistic performance measurements,...

SPLITTER: A data model and algorithm for detecting spectral lines and continuum emission of high-redshift galaxies using DESHIMA 2.0

We propose the Stationary spectrum Plus Low-rank Iterative TransmiTtance EstimatoR (SPLITTER) for removing wideband atmospheric noise from observations of high-redshift galaxies. This algorithm has specifically been developed for the DEep Spectroscopic HIgh-redshift MApper (DESHIMA) 2.0, a spectrometer that is designed to observe the waveband...

A small radio galaxy at z = 4.026

Less than 200 radio-loud active galactic nuclei are known above redshift 4. Around 40 of them have been observed at milliarcsecond (mas) scale resolution with very long baseline interferometry (VLBI) technique. Some of them are unresolved, compact, relativistically beamed objects, and blazars with jets pointing at small angles to the observer...