MeerKAT

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Search and identification of transient and variable radio sources using MeerKAT observations: a case study on the MAXI J1820+070 field

(2022)

Authors:

A Rowlinson, J Meijn, J Bright, AJ van der Horst, S Chastain, S Fijma, R Fender, I Heywood, RAMJ Wijers, PA Woudt, A Andersson, GR Sivakoff, E Tremou, LN Driessen

Radio detections of IR-selected runaway stellar bow shocks

Monthly Notices of the Royal Astronomical Society Oxford University Press 512:4 (2022) 5374-5389

Authors:

J Van den Eijnden, P Saikia, S Mohamed

Abstract:

Massive stars moving at supersonic peculiar velocities through the interstellar medium (ISM) can create bow shocks, arc-like structures at the interface between the stellar wind and the ISM. Many such bow shocks have been detected and catalogued at IR wavelengths, but detections in other wavebands remain rare. Strikingly, while electrons are expected to be accelerated in the bow shock and their non-thermal emission may include synchrotron emission at low frequencies, only two massive runaway stellar bow shocks have to date been detected in the radio band. Here, we examine a sample of fifty IR-detected bow shocks from the E-BOSS catalogues in recently released radio images from the Rapid ASKAP Continuum Survey. We identify three confident and three likely counterparts, as well as three inconclusive candidates requiring confirmation via follow-up observations. These detections significantly increase the number of known radio massive stellar bow shocks and highlight the advantage of dedicated searches with current and next-generation radio telescopes. We investigate the underlying radio emission mechanism for these radio sources, finding a mix of free鈥揻ree-dominated and synchrotron-dominated systems. We also discuss the non-detected targets by putting constraints on their emission properties and investigating their detectability with future observations. Finally, we propose several future avenues of research to advance the study and understanding of bow shocks at radio frequencies.

Radio detections of IR-selected runaway stellar bow shocks

ArXiv 2203.10842 (2022)

Authors:

J Van den Eijnden, P Saikia, S Mohamed

21 new long-term variables in the GX 339-4 field: two years of MeerKAT monitoring

(2022)

Authors:

LN Driessen, BW Stappers, E Tremou, RP Fender, PA Woudt, R Armstrong, S Bloemen, P Groot, I Heywood, A Horesh, AJ van der Horst, E Koerding, VA McBride, JCA Miller-Jones, KP Mooley, A Rowlinson, RAMJ Wijers

Active Galactic Nuclei population studies with the Cherenkov Telescope Array

Proceedings of Science 395 (2022)

Authors:

H Abdalla, H Abe, S Abe, A Abusleme, F Acero, A Acharyya, V Ac铆n Portella, K Ackley, R Adam, C Adams, SS Adhikari, I Aguado-Ruesga, I Agudo, R Aguilera, A Aguirre-Santaella, F Aharonian, A Alberdi, R Alfaro, J Alfaro, C Alispach, R Aloisio, R Alves Batista, JP Amans, L Amati, E Amato, L Ambrogi, G Ambrosi, M Ambrosio, R Ammendola, J Anderson, M Anduze, EO Ang眉ner, LA Antonelli, V Antonuccio, P Antoranz, R Anutarawiramkul, J Aragunde Gutierrez, C Aramo, A Araudo, M Araya, A Arbet-Engels, C Arcaro, V Arendt, C Armand, T Armstrong, F Arqueros, L Arrabito, B Arsioli, M Artero, K Asano, Y Ascas铆bar, J Aschersleben, M Ashley, P Attin脿, P Aubert, CB Singh, D Baack, A Babic, M Backes, V Baena, S Bajtlik, A Baktash, C Balazs, M Balbo, O Ballester, J Ballet, B Balmaverde, A Bamba, R Bandiera, A Baquero Larriva, P Barai, C Barbier, V Barbosa Martins, M Barcelo, M Barkov, M Barnard, L Baroncelli, U Barres de Almeida, JA Barrio, D Bastieri, PI Batista, I Batkovic, C Bauer, R Bautista-Gonz谩lez, J Baxter, U Becciani, J Becerra Gonz谩lez, Y Becherini, G Beck, J Becker Tjus, W Bednarek, A Belfiore, L Bellizzi, R Belmont, W Benbow, D Berge, E Bernardini, MI Bernardos, K Bernl枚hr, A Berti

Abstract:

The Cherenkov Telescope Array (CTA) observatory is the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Building on the strengths of current IACTs, CTA is designed to achieve an order of magnitude improvement in sensitivity, with unprecedented angular and energy resolution. CTA will also increase the energy reach of IACTs, observing photons in the energy range from 20 GeV to beyond 100 TeV. These advances in performance will see CTA heralding in a new era for high-energy astrophysics, with the emphasis shifting from source discovery, to population studies and precision measurements. In this talk we discuss CTA鈥檚 ability to conduct source population studies of 纬-ray bright active galactic nuclei and how this ability will enhance our understanding on the redshift evolution of this dominant 纬-ray source class.