2023

Paper by CfAR Director Prof. Turlough Downes features as a scientific highlight in the ALMA newsletter
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Length-scales and dynamics of Carina's Western wall
T. P. Downes (CfAR), P. Hartigan and A. Isella
Published in Monthly Notices of the Royal Astronomical Society
We analyse observations of a photo-dissociation region in the Carina Nebula (the so-called Western Wall). Through the use of well-known analysis such as Principal Component Analysis, as well as a new analysis involving wavelets developed for this work, we identify that the length-scale of 0.02 pc to 0.03 pc is important for the dynamics here. We suggest that this length-scale is engendered by the interplay between the turbulent cascade and self-gravity. Finally, we demonstrate that analysis of the shape of a photo-dissociation region can give important information about the density structures in the associated undisturbed molecular cloud.

2022

ALMA Data Cubes and Continuum Maps of the Irradiated Western Wall in Carina
P. Hartigan, M. Hummel, A. Isella and T. P. Downes (CfAR).
Published in Astronomical Journal
This paper presents ALMA observations of the Western Wall in Carina. We identify 254 distinct, possibly star-forming, cores which have a mass distribution similar to the stellar Initial Mass Function. We don't find any direct evidence for triggered star formation, despite the intense radiation field from nearly OB associations, although the densest part of the cloud lies closest to the photo-dissociation region which hints at this.

Stellar versus Galactic: The intensity of energetic particles at the evolving Earth and young exoplanets
D. Rodgers-Lee, A. Vidotto, A. Taylor, P. Rimmer and T.P.Downes (CfAR)
Published in 37th International Cosmic Ray Conference
Energetic particles produced by a young Sun may have been important for the origin of life on Earth
by driving the formation of prebiotic molecules. In this work we calculate the intensity of energetic particles, both from
the Sun and from our Galaxy, on Earth at a time when life is thought to have begun. The model is also applied to a young,
warm Jupiter-like planet orbiting at 20AU from its host star (HR2562b).

Mode-sum prescription for the renormalized stress-energy tensor on black hole spacetimes
P. Taylor (CfAR), C. Breen and A.C. Ottewill.
Published in Physical Review D
In this paper, we describe an extremely efficient method for computing the renormalized stress-energy tensor of a quantum scalar field in spherically symmetric black hole spacetimes. The method applies to a scalar field with arbitrary field parameters. We demonstrate the utility of the method by computing the renormalized stress-energy tensor for a scalar field in the Schwarzschild black hole spacetime, applying our results to discuss the null energy condition and the semiclassical backreaction.

Response of an Unruh-DeWitt detector near an extremal black hole
A. Conroy and P. Taylor (CfAR).
Published in Physical Review D
We consider the response of an Unruh-DeWitt detector near an extremal charged black hole, modeling the near-horizon region of this extremal spacetime by the Bertotti-Robinson spacetime. The advantage of employing the Bertotti-Robinson limit is that the two-point functions for a massless scalar field are obtainable in closed form for the field in a number of quantum states of interest. We consider the detector coupled to a massless field in both the Boulware vacuum state and arbitrary thermal states, including the Hartle-Hawking state, and analyze the detector’s response for a broad range of trajectories. Particular attention is paid to the thermalization of the detector, the anti-Unruh and anti-Hawking effect.

Improved binary solution for the gamma-ray binary 1FGL J1018.6-5856
Published in Monthly Notices of the Royal Astronomical Society
B. van Soelen, S. McKeague (CfAR), D. Malyshev, M. Chernyakova (CfAR), N. Komin, N. Matchett, I.M. Monageng
Using new observations of 1FGL J1018.6-5856 with SALT, along with analysis of X-ray and GeV observations, an improved binary solution has been found for the system, starting with a refined periodicity based on searches made in the Fermi-LAT observational data.

Spin Hall effects and the localization of massless spinning particles
A.I. Harte (CfAR) and M.A. Oancea
Published in Physical Review D
The path of a light ray can be affected by its angular momentum. This is described in the optics community as the "spin Hall effect." It and related concepts, such as Wigner translations, are shown in this paper to be special cases of old results in the general relativistic theory of extended-body motion. This paper also demonstrates that light with angular momentum must have mass. In fact, massless spinning objects are shown to be impossible without violating energy conditions. If a massless spinning object did exist, it would have pathological properties: Reasonably-defined centroids could lie arbitrarily far from the object itself, invalidating any simple description for its motion. While light with angular momentum is "almost" massless, this is shown to be a delicate approximation which must be treated with care. 

The Faraday Rotation Measure Grid of the LOFAR Two-metre Sky Survey: Data Release 2
S. P. O'Sullivan (CfAR), T. W. Shimwell, M. J. Hardcastle, C. Tasse, G. Heald, E. Carretti, M. Brüggen, V. Vacca, C. Sobey, C. L. Van Eck, C. Horellou, R. Beck, M. Bilicki, S. Bourke, A. Botteon, J. H. Croston, A. Drabent, K. Duncan, V. Heesen, S. Ideguchi, M. Kirwan, L. Lawlor, B. Mingo, B. Nikiel-Wroczyński, J. Piotrowska, A. M. M. Scaife, R. J. van Weeren
Published in Monthly Notices of the Royal Astronomical Society (MNRAS)
Description paper of a publicly released catalogue of extragalactic Faraday rotation measure values, derived using data from the LOFAR radio telescope. This work is part of Data Release 2 from the LOFAR Two-metre Sky Survey (LoTSS), covering ~27% of the Northern sky. This catalogue is a valuable resource for the study of cosmic magnetism. 

Detection of magnetic fields in the circumgalactic medium of nearby galaxies using Faraday rotation
V. Heesen, S. P. O'Sullivan (CfAR), M. Brüggen, A. Basu, R. Beck, A. Seta, E. Carretti, M. G. H. Krause, M. Haverkorn, S. Hutschenreuter, A. Bracco, M. Stein, D. J. Bomans, R.-J. Dettmar, K. T. Chyży, G. H. Heald, R. Paladino, C. Horellou
Published in Astronomy & Astrophysics (A&A)
Using the Faraday rotation measure values from the catalogue of O’Sullivan et al. (2023), we find evidence for the existence of strong magnetic fields in the circumgalactic medium in a region extending from the minor axes of nearby star-forming galaxies. 

Magnetic field evolution in cosmic filaments with LOFAR data
E. Carretti, S. P. O'Sullivan, V. Vacca, F. Vazza, C. Gheller, T. Vernstrom, A. Bonafede
Published in Monthly Notices of the Royal Astronomical Society (MNRAS)
Here we compare the redshift evolution of the Faraday rotation measure associated with filaments of the cosmic web of structure with cosmological MHD numerical simulations. This allows us to rule out specific models for the origin of cosmic magnetic fields, in addition to indicating plausible magnetogenesis scenarios which are still consistent with the data. 

The redshift evolution of extragalactic magnetic fields
​Valentin Pomakov, Shane P. O'Sullivan, Marcus Bruggen, Franco Vazza, Ettore Carretti, George Heald, Cathy Horellou, Timothy Shimwell, Aleksandar Shulevski, Tessa Vernstrom
Published in Monthly Notices of the Royal Astronomical Society (MNRAS)
We use observations of close pairs of Faraday rotation measure values on the sky, in combination with a Monte Carlo model of extragalactic magnetic fields, to provide a robust upper limit on the strength of a uniform, primordial magnetic field. 

Frequency Domain Multiplexing for Microwave Kinetic Inductance Detectors: Comparing the Xilinx ZCU111 RFSoC with their new 2x2 RFSoC board
Baldwin, De Lucia, Bracken, Ulbricht, Creaner (CfAR), Piercy, Ray
Published in Journal of Low Temperature Physics 

A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics
The XENONnT Collaboration, The LUX-ZEPLIN (LZ) Collaboration, The DARWIN collaboration et al.
Published in Journal of Physics G

Cosmogenic production of 37Ar in the context of the LUX-ZEPLIN experiment 
The LUX-ZEPLIN (LZ) Collaboration
Published in Physical Review D

Repurposing ROACH-1 boards for prototyping of readout systems for optical-NIR MKIDs
O. Creaner (CfAR), C. Bracken, J. Piercy, G. Ulbricht, E. Baldwin, M. De Lucia, T. Ray
Published in X-Ray, Optical, and Infrared Detectors for Astronomy X 
Highly uniform superconducting Titanium Nitride – Titanium multilayers for MKIDs arrays for astronomical applications
M. De Lucia, J. D. Piercy, G. Ulbricht, E. Baldwin, O. Creaner (CfAR), C. Bracken and T. Ray
Published in X-Ray, Optical, and Infrared Detectors for Astronomy X

The Locus Algorithm: The design, implementation and performance characterisation of a software and grid computing system to optimise the quality of fields of view for differential photometry
O. Creaner (CfAR), E. Hickey, J. Walsh, K. Nolan
Published in Astronomy and Computing  
The Locus Algorithm: A technique for identifying optimised pointings for differential photometry
Creaner (CfAR), Nolan, Hickey and Smith
Published in Astronomy and Computing