Article
Astronomy & Astrophysics
E. F. Ocran, M. Vaccari, J. M. Stil, A. R. Taylor, C. H. Ishwara-Chandra, Jae-Woo Kim
Summary: We measure the specific star formation rates (sSFRs) of K-band selected galaxies using radio data to probe the nature of galaxies below the noise and confusion limits. Our study shows that the sSFR-mass relation steepens with redshift, indicating a 'downsizing' process where massive galaxies form stars earlier and more rapidly than low-mass galaxies. We find a general agreement in the sSFR-M-star plane when comparing our results to those from literature.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alexei Baskin, Ari Laor
Summary: The effects of radiation pressure compression on ionized gas in AGNs sets the density structure of photoionized gas. The predictions of free-free emission and absorption properties based on RPC models match observations, showing an increase in absorption frequency and potential dominance of radio continuum above 100 GHz. Excess emission observed in NGC 1068 with ALMA is consistent with predicted free-free emission, indicating the presence of warm photoionized gas in AGNs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
J. F. Radcliffe, P. D. Barthel, M. A. Garrett, R. J. Beswick, A. P. Thomson, T. W. B. Muxlow
Summary: This study investigates the nature of apparently radio-silent, X-ray-luminous AGN and their host galaxies, finding that around half of the X-ray-luminous AGN population actually lack jet-driven radio emission, residing in normal star-forming galaxies. This suggests that AGN- or jet-driven radio emission may not always be active in galaxies with actively accreting black holes, classifying them as radio-silent AGN.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
B. Webster, J. H. Croston, J. J. Harwood, R. D. Baldi, M. J. Hardcastle, B. Mingo, H. J. A. Rottgering
Summary: The study confirmed the nature of nine potential galaxy scale jets using LOFAR data and discovered some galaxies that never grow beyond the GSJ stage. Analysis of spectral ages and lobe expansion speeds indicated that these GSJ have a significant impact on the evolution of the host galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Rohit Kondapally, Philip N. Best, Mojtaba Raouf, Nicole L. Thomas, Romeel Dave, Stanislav S. Shabala, Huub J. A. Rottgering, Martin J. Hardcastle, Matteo Bonato, Rachel K. Cochrane, Katarzyna Malek, Leah K. Morabito, Isabella Prandoni, Daniel J. B. Smith
Summary: Radio-mode feedback is crucial for reproducing the properties of massive galaxies. We studied the cosmic evolution of radio-active galactic nuclei (AGN) feedback using a sample of 9485 radio-excess AGN. Low-excitation radio galaxies dominate the feedback activity, showing a constant heating output across a certain redshift range. Comparisons with simulations and models support the idea of self-regulated AGN feedback, with AGN jets playing a significant role throughout cosmic history.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Andrea Guerrero, Neil Nagar, Kotaro Kohno, Seiji Fujimoto, Vasily Kokorev, Gabriel Brammer, Jean-Baptiste Jolly, Kirsten Knudsen, Fengwu Sun, Franz E. Bauer, Gabriel B. Caminha, Karina Caputi, Gerald Neumann, Gustavo Orellana-Gonzalez, Pierluigi Cerulo, Jorge Gonzalez-Lopez, Nicolas Laporte, Anton M. Koekemoer, Yiping Ao, Daniel Espada, Alejandra M. Munoz Arancibia
Summary: This study develops new tools for analyzing ALMA data and applies them to the ALMA Lensing Cluster Survey. By stacking the data, the study derives average dust masses, gas masses, and star-formation rates of star-forming galaxies. The results show that both cluster and field galaxies have lower average SFRs compared to main-sequence galaxies, and only galaxies with higher stellar masses exhibit dust and gas fractions comparable to main-sequence galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Fangxia An, M. Vaccari, Ian Smail, M. J. Jarvis, I. H. Whittam, C. L. Hale, S. Jin, J. D. Collier, E. Daddi, J. Delhaize, B. Frank, E. J. Murphy, M. Prescott, S. Sekhar, A. R. Taylor, Y. Ao, K. Knowles, L. Marchetti, S. M. Randriamampandry, Z. Randriamanakoto
Summary: The study investigates the radio spectral properties of 2094 star-forming galaxies using various radio data sources and finds that the radio spectrum slightly steepens with increasing stellar mass at specific frequency ranges.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Takayuki J. Hayashi, Yoshiaki Hagiwara, Masatoshi Imanishi
Summary: The study reveals that ULIRGs have common radiative processes regardless of the presence of optical AGNs. Some ULIRGs show contributions from AGNs, such as IRAS00188-0856. Additionally, the extended emission associated with IRAS01004-2237 is likely originated from AGN activity rather than merger-induced.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. Ghasemi-Nodehi, Fatemeh S. Tabatabaei, Mark Sargent, Eric J. Murphy, Habib Khosroshahi, Rob Beswick, Anna Bonaldi, Eva Schinnerer
Summary: Resolved maps of thermal and non-thermal radio continuum emission of distant galaxies provide valuable insights into the role of interstellar medium in galaxy evolution. Simulations of radio surface brightness of star-forming galaxies at different redshifts reveal flattening synchrotron spectra and increasing thermal fractions with redshift. Higher mass galaxies have lower thermal fractions and experience faster flattening of non-thermal spectra. The proposed SKA1-MID band 2 reference survey can detect the interstellar medium in M51 and NGC 6946-like galaxies up to redshift 3. Adding band 1 is essential for proper separation of radio continuum emitting processes at the peak of star formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
B. Webster, J. H. Croston, B. Mingo, R. D. Baldi, B. Barkus, G. Gurkan, M. J. Hardcastle, R. Morganti, H. J. A. Rottgering, J. Sabater, T. W. Shimwell, C. Tasse, G. J. White
Summary: The study discusses the feedback effects from low-luminosity radio-loud AGN and presents the discovery of a population of 195 radio galaxies with small galaxy-scale jets (GSJ) that directly influence the evolution of their host galaxies. The findings reveal that GSJ are ordinary AGN at a stage shortly after the radio emission has expanded beyond the central regions of the host, with some showing energy levels capable of impacting the host's evolution. This sample of GSJ is expected to expand with future releases of data and can serve as a basis for further research on feedback from low-luminosity radio sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
K. Ross, J. R. Callingham, N. Hurley-Walker, N. Seymour, P. Hancock, T. M. O. Franzen, J. Morgan, S. White, M. E. Bell, P. Patil
Summary: Studies of spectral variability for a large population of extragalactic radio sources are now possible, with variability more prevalent in peaked-spectrum sources. Observations suggest that the radio sky in the megahertz regime is more dynamic than previously suggested.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
S. Mandal, I Prandoni, M. J. Hardcastle, T. W. Shimwell, H. T. Intema, C. Tasse, R. J. van Weeren, H. Algera, K. L. Emig, H. J. A. Roettgering, D. J. Schwarz, T. M. Siewert, P. N. Best, M. Bonato, M. Bondi, M. J. Jarvis, R. Kondapally, S. K. Leslie, V. H. Mahatma, J. Sabater, E. Retana-Montenegro, W. L. Williams
Summary: With new low-frequency telescopes like LOFAR and improved calibration techniques, we are now able to explore the subgigahertz radio sky in unprecedented depth and sensitivity. The ongoing LoTSS project is observing the entire northern radio sky, with deep observations revealing interesting features such as a pronounced drop and bump in radio source counts that cannot be explained by existing evolutionary models.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. Nandi, M. Das, K. S. Dwarakanath
Summary: ULIRGs are galaxies characterized by large infrared luminosities, large dust masses, and vigorous star formation, possibly representing the final stages of mergers of gas-rich spiral galaxies. While most ULIRGs do not show kpc scale extended radio emission associated with nuclear activity, their radio spectral energy distributions do exhibit characteristics of young radio galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
L. N. Driessen, B. W. Stappers, E. Tremou, R. P. Fender, P. A. Woudt, R. Armstrong, S. Bloemen, P. Groot, I Heywood, A. Horesh, A. J. van der Horst, E. Koerding, V. A. McBride, J. C. A. Miller-Jones, K. P. Mooley, A. Rowlinson, R. A. M. J. Wijers
Summary: In this article, we present 21 new long-term variable radio sources discovered during 2 years of weekly monitoring of the low-mass X-ray binary GX 339-4 using MeerKAT. These sources exhibit variability on time-scales ranging from weeks to months, with a variety of light-curve shapes and spectral index properties. The cause of the variability is likely refractive scintillation of active galactic nuclei in most cases.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Ross, N. Hurley-Walker, N. Seymour, J. R. Callingham, T. J. Galvin, M. Johnston-Hollitt
Summary: Characterizing the spectral variability of radio sources can help determine the physical processes involved and provide evidence to support absorption models. In this study, we observed 15 peaked-spectrum sources with the Australia Telescope Compact Array and the Murchison Widefield Array, and found that the variability at megahertz frequencies is mainly caused by refractive interstellar scintillation. We also identified sources with changes in spectral shape, possibly due to variable optical depth or jet ejections.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
T. Pasini, H. W. Edler, M. Brueggen, F. de Gasperin, A. Botteon, K. Rajpurohit, R. J. van Weeren, F. Gastaldello, M. Gaspari, G. Brunetti, V. Cuciti, C. Nanci, G. di Gennaro, M. Rossetti, D. Dallacasa, D. N. Hoang, C. J. Riseley
Summary: In this study, radio observations and X-ray data were used to investigate the radio sources in the galaxy cluster Abell 1550. A ultra-steep spectrum radio halo, a radio relic, and a radio phoenix were detected. The halo is likely produced by turbulence induced by a major merger, while the relic and phoenix could be attributed to shocks.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Schmidt, F. Geyer, S. Froese, P-S Blomenkamp, M. Brueggen, F. de Gasperin, D. Elsaesser, W. Rhode
Summary: The authors developed a deep learning-based method for reconstructing radio interferometric images from incomplete information. The method can generate reproducible images, but the recovered fluxes show substantial scatter.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Rajpurohit, R. J. van Weeren, M. Hoeft, F. Vazza, M. Brienza, W. Forman, D. Wittor, P. Dominguez-Fernandez, S. Rajpurohit, C. J. Riseley, A. Botteon, E. Osinga, G. Brunetti, E. Bonnassieux, A. Bonafede, A. S. Rajpurohit, C. Stuardi, A. Drabent, M. Brueggen, D. Dallacasa, T. W. Shimwell, H. J. A. Rottgering, F. de Gasperin, G. K. Miley, M. Rossetti
Summary: Deep and high-fidelity images of the merging galaxy cluster A2256 are presented using uGMRT and LOFAR, revealing the complex structure of a prominent relic within the cluster. The observations suggest that the complex filaments are caused by regions with higher Mach numbers.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
X. Zhang, A. Simionescu, F. Gastaldello, D. Eckert, L. Camillini, R. Natale, M. Rossetti, G. Brunetti, H. Akamatsu, A. Botteon, R. Cassano, V. Cuciti, L. Bruno, T. W. Shimwell, A. Jones, J. S. Kaastra, S. Ettori, M. Brueggen, F. de Gasperin, A. Drabent, R. J. van Weeren, H. J. A. Roettgering
Summary: By analyzing the data from the LOFAR Two-metre Sky Survey (LoTSS-DR2), the study investigates the relationship between extended radio sources and the dynamic states of galaxy clusters. It finds a correlation between intracluster medium turbulence and radio halos, supporting the turbulent (re)acceleration scenario. Additionally, a new quantity [k(B)T center dot Y-X](rRH) is introduced, which is strongly correlated with radio halo power.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Rafael I. J. Mostert, Kenneth J. Duncan, Lara Alegre, Huub J. A. Rottgering, Wendy L. Williams, Philip N. Best, Martin J. Hardcastle, Raffaella Morganti
Summary: The study aims to automate the radio component association of large (>15 arcsec) radio components using machine learning. By turning the association problem into a classification problem, an adapted Fast region-based convolutional neural network was trained to mimic expert annotations. Through data augmentation and using predictions from an existing gradient boosting classifier, the model simplifies the component association process, providing same associations as manual efforts in 85.3% of cases.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Lara Alegre, Jose Sabater, Philip Best, Rafael I. J. Mostert, Wendy L. Williams, Gulay Gurkan, Martin J. Hardcastle, Rohit Kondapally, Tim W. Shimwell, Daniel J. B. Smith
Summary: This paper uses machine learning to classify and associate radio sources, improving model performance, and the results have important practical applications.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
R. Cassano, V. Cuciti, G. Brunetti, A. Botteon, M. Rossetti, L. Bruno, A. Simionescu, F. Gastaldello, R. J. van Weeren, M. Brueggen, D. Dallacasa, X. Zhang, H. Akamatsu, A. Bonafede, G. Di Gennaro, T. W. Shimwell, F. de Gasperin, H. J. A. Roettgering, A. Jones
Summary: We investigate the properties of radio haloes in galaxy clusters using observations from the Planck Sunyaev Zel'dovich-detected sources catalog and the LOFAR Two-meter Sky Survey. The observed number, flux density, and redshift distributions of radio haloes are consistent with expectations from the re-acceleration scenario. The fraction of clusters with radio haloes increases with cluster mass, confirming the importance of gravitational processes in halo generation. We also find evidence for a population of radio haloes with very steep spectra preferentially detected by LOFAR. The morphological analysis reveals a preference for radio haloes in merging systems, with a larger fraction of newly-discovered haloes in less disturbed systems.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
V. Heesen, F. de Gasperin, S. Schulz, A. Basu, R. Beck, M. Brueggen, R. -J. Dettmar, M. Stein, L. Gajovic, F. S. Tabatabaei, P. Reichherzer
Summary: This study measures the distance that cosmic-ray electrons are transported in the nearby galaxy M 51 across different cosmic-ray energy levels using ultra-low frequency observations from LOFAR and ancillary data. It is found that the transport length of cosmic-ray electrons increases at low frequencies.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
F. de Gasperin, H. W. Edler, W. L. Williams, J. R. Callingham, B. Asabere, M. Brueggen, G. Brunetti, T. J. Dijkema, M. J. Hardcastle, M. Iacobelli, A. Offringa, M. J. Norden, H. J. A. Rottgering, T. Shimwell, R. J. van Weeren, C. Tasse, D. J. Bomans, A. Bonafede, A. Botteon, R. Cassano, K. T. Chyzy, V. Cuciti, K. L. Emig, M. Kadler, G. Miley, B. Mingo, M. S. S. L. Oei, I. Prandoni, D. J. Schwarz, P. Zarka
Summary: LOFAR is the only existing radio interferometer capable of observing at ultra-low frequencies with high resolution and high sensitivity. The LOFAR Surveys Key Science Project is conducting the LOFAR LBA Sky Survey (LoLSS), which covers the whole northern sky above declination 24. The first data release includes calibrated images and catalogues, with improved sensitivity and resolution compared to the preliminary release.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Gajovic, F. Welzmueller, V. Heesen, F. de Gasperin, M. Vollmann, M. Brueggen, A. Basu, R. Beck, D. J. Schwarz, D. J. Bomans, A. Drabent
Summary: By using the non-detection of 150 MHz radio continuum emission from dwarf spheroidal (dSph) galaxies with the LOw Frequency ARray (LOFAR), we derived constraints on the annihilation cross section of weakly interacting massive particles (WIMPs) in electron-positron pairs. Our results provide upper limits on the WIMP cross section, assuming diffusion approximation and the existence of magnetic fields in cosmic ray transport.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Boehme, D. J. Schwarz, F. de Gasperin, H. J. A. Roettgering, W. L. Williams
Summary: This study aims to combine the LOFAR LBA Sky Survey (LoLSS) data with other high-frequency surveys to investigate the spectral properties of a large sample of radio sources. A new cross-matching algorithm that considers the sizes of the radio sources is presented and applied to multiple catalogues. The results show that the majority of the LoLSS sources have counterparts, and the average spectral indexes between LoLSS and NVSS, as well as LoLSS and LoTSS-DR2, are determined.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
A. Boselli, P. Serra, F. de Gasperin, B. Vollmer, P. Amram, H. W. Edler, M. Fossati, G. Consolandi, P. Cote, J. C. Cuillandre, L. Ferrarese, S. Gwyn, J. Postma, M. Boquien, J. Braine, F. Combes, G. Gavazzi, G. Hensler, M. A. Miville-Deschenes, M. Murgia, J. Roediger, Y. Roehlly, R. Smith, H. X. Zhang, N. Zabel
Summary: We present the first results of a pilot observation using the MeerKAT radio telescope for the ViCTORIA project. High-quality data allowed us to detect an extended low column density H I gas tail associated with the dwarf irregular galaxy NGC 4523. This tail suggests that the galaxy is experiencing hydrodynamic interaction with the surrounding hot intracluster medium.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Alessandro Ignesti, Marisa Brienza, Benedetta Vulcani, Bianca M. Poggianti, Antonino Marasco, Rory Smith, Martin J. Hardcastle, Andrea Botteon, Ian D. Roberts, Jacopo Fritz, Rosita Paladino, Myriam Gitti, Anna Wolter, Neven Tomicic, Sean McGee, Alessia Moretti, Marco Gullieuszik, Alexander Drabent
Summary: We report the serendipitous discovery of an unprecedented interaction between the radio lobe of a radio galaxy and a spiral galaxy. The interaction, which occurred between the central galaxy GIN 049 and the spiral galaxy JO36, resulted in a positive feedback event for JO36, leading to a significant increase in its star formation rate.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
M. Stimpson, M. J. Hardcastle, M. G. H. Krause
Summary: In this study, we present relativistic magnetohydrodynamic simulations of jets interacting with spherically symmetric cluster atmospheres. By analyzing synthetic emission maps and examining dynamic, energetic, and polarimetric data, we find that the cluster atmosphere and jet power play a crucial role in shaping the morphology and energy distribution of the jets.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)