Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies

Gasperin, F. de; Vink, Jacco; McKean, J. P.; Asgekar, A.; Avruch, I. M.; Bentum, Mark J.; Blaauw, R.; Bonafede, A.; Broderick, J. W.; Brüggen, M.; Breitling, F.; Brouw, W. N.; Butcher, H. R.; Ciardi, B.; Cuciti, V.; Vos, M. de; Duscha, S.; Eislöffel, J.; Engels, D.; Fallows, R. A.; Franzen, T. M. O.; Garrett, M. A.; Gunst, A. W.; Hörandel, J. R.; Heald, G.; Hoeft, M.; Iacobelli, M.; Koopmans, L. V. E.; Krankowski, Andrzej; Maat, P.; Mann, G.; Mevius, M.; Miley, G. K.; Morganti, Raffaella; Nelles, A.; Norden, M. J.; Offringa, A. R.; Orrù, E.; Paas, H.; Pandey, V. N.; Pandey-Pommier, M.; Pekal, R.; Pizzo, R.; Reich, W.; Rowlinson, A.; Röttgering, H. J. A.; Schwarz, Dominik J.; Shulevski, A.; Smirnov, O.; Sobey, C.; Soida, M.; Steinmetz, Matthias; Tagger, M.; Toribio, M. C.; Ardenne, A. van; Horst, A. J. van der; Haarlem, M. P. van; Weeren, R. J. van; Vocks, C.; Wucknitz, O.; Zarka, Philippe; Zucca, Pietro

doi:10.1051/0004-6361/201936844

Cited by 24 publications

(9 citation statements)

References 51 publications

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“…Detailed sky models for the four brightest among these sources in the 30–77 MHz range were derived by de Gasperin et al. (2020) using the Low Frequency Array.…”

Section: The Dlite Systemmentioning

confidence: 99%

The Deployable Low‐Band Ionosphere and Transient Experiment

et al. 2021

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The Deployable Low‐Band Ionosphere and Transient Experiment (DLITE) is a four‐element interferometric radio telescope made from mostly commercial off‐the‐shelf parts to minimize costs and maximize ease of deployment. It operates in the high frequency and very high frequency (VHF) regimes, nominally in a 30–40 MHz band, but with good sensitivity (sky‐noise dominated) in the 20–80 MHz range. Its configuration is optimized to probe ionospheric structure using the so‐called “A‐Team,” exceptionally bright sources of cosmic radio emission. Methods have been developed to track the apparent positions and intensities of A‐Team sources without the need for beam forming to enable measurements of VHF scintillations as well as total electron content gradients. Time difference of arrival and frequency difference of arrival methods have been adapted for all‐sky imaging to facilitate both statistical measurements of scintillation levels and time domain astronomy. This study provides a detailed description of the system design, the analysis algorithms, and the science that can be conducted using results from two prototype DLITE systems in Maryland and New Mexico.

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“…Detailed sky models for the four brightest among these sources in the 30–77 MHz range were derived by de Gasperin et al. (2020) using the Low Frequency Array.…”

Section: The Dlite Systemmentioning

confidence: 99%

The Deployable Low‐Band Ionosphere and Transient Experiment

et al. 2021

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“…By measuring the properties of the low-frequency turnover in compact sources and hotspots, we can evaluate the relative importance of synchrotron self-absorption, free-free absorption, or a low-energy cut-off (e.g. McKean et al 2016;de Gasperin et al 2020c). Furthermore, the combination of LoLSS, LoTSS and higher-frequency surveys such as NVSS or Apertif will enable the study of spectral curvature over a wide frequency band for a large number of sources (∼ 1, 000, 000; considering the northern hemisphere).…”

Section: Radio-loud Agnmentioning

confidence: 99%

The LOFAR LBA Sky Survey

Gasperin

Williams

Best

et al. 2021

A&A

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Context. The LOw Frequency ARray (LOFAR) is the only radio telescope that is presently capable of high-sensitivity, high-resolution (i.e. < 1 mJy beam −1 and < 15) observations at ultra-low frequencies (< 100 MHz). To utilise these capabilities, the LOFAR Surveys Key Science Project is undertaking a large survey to cover the entire northern sky with Low Band Antenna (LBA) observations. Aims. The LOFAR LBA Sky Survey (LoLSS) aims to cover the entire northern sky with 3170 pointings in the frequency range between 42 − 66 MHz, at a resolution of 15 and at a sensitivity of 1 mJy beam −1 (1σ). In this work, we outline the survey strategy, the observational status, and the calibration techniques. We also briefly describe several of our scientific motivations and present the preliminary public data release. Methods. The preliminary images were produced using a fully automated pipeline aimed at correcting all direction-independent effects in the data. Whilst the direction-dependent effects, such as those from the ionosphere, have not yet been corrected, the images presented in this work are still ten times more sensitive than previous available surveys at these low frequencies. Results. The preliminary data release covers 740 deg 2 around the HETDEX spring field region at an angular resolution of 47 with a median noise level of 5 mJy beam −1. The images and the catalogue of 25,247 sources have been publicly released. We demonstrate that the system is capable of reaching a root mean square (rms) noise of 1 mJy beam −1 and an angular resolution of 15 once directiondependent effects are accounted for. Conclusions. LoLSS will provide the ultra-low-frequency information for hundreds of thousands of radio sources, providing critical spectral information and producing a unique data set that can be used for a wide range of science topics, such as the search for high redshift galaxies and quasars, the study of the magnetosphere of exoplanets, and the detection of the oldest populations of cosmic-rays in galaxies, clusters of galaxies, as well as those produced by active galactic nuclei (AGN).

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“…It has since come to our attention that this value was dominated by a few degenerate pixels that contributed disproportionately to the mass estimate. We have redone the analysis using the complete LOFAR Cas A LBA data set presented in de Gasperin et al (2020), with twice the observing time and five times the bandwidth of the original study, and using a more stringent mask of degenerate pixels. As intermediate products for the broad-band imaging, de Gasperin et al ( 2020) produced 61 narrow-band images of Cas A in the frequency range of 30-77 MHz.…”

Section: Physical Conditions In Cas Amentioning

confidence: 99%

Dust destruction and survival in the Cassiopeia A reverse shock

Priestley

Arias

Barlow

2021

Monthly Notices of the Royal Astronomical Society

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Core-collapse supernovae (CCSNe) produce large ($\gtrsim0.1\,{\rm M}_\odot$) masses of dust, and are potentially the primary source of dust in the Universe, but much of this dust may be destroyed before reaching the interstellar medium. Cassiopeia A (Cas A) is the only supernova remnant where an observational measurement of the dust destruction efficiency in the reverse shock is possible at present. We determine the pre- and post-shock dust masses in Cas A using a substantially improved dust emission model. In our preferred models, the unshocked ejecta contains $0.6\!-\!0.8\,{\rm M}_\odot$ of $0.1\,{\rm \mu m}$ silicate grains, while the post-shock ejecta has $0.02\!-\!0.09\,{\rm M}_\odot$ of $5\!-\!10 \, {\rm nm}$ grains in dense clumps, and $2 \times 10^{-3}\,{\rm M}_\odot$ of $0.1 \, {\rm \mu m}$ grains in the diffuse X-ray emitting shocked ejecta. The implied dust destruction efficiency is $74\!-\!94\,{\rm per\,cent}$ in the clumps and $92\!-\!98\,{\rm per\,cent}$ overall, giving Cas A a final dust yield of $0.05\!-\!0.30\,{\rm M}_\odot$. If the unshocked ejecta grains are larger than $0.1\,{\rm \mu m}$, the dust masses are higher, the destruction efficiencies are lower, and the final yield may exceed $0.5\,{\rm M}_\odot$. As Cas A has a dense circumstellar environment and thus a much stronger reverse shock than is typical, the average dust destruction efficiency across all CCSNe is likely to be lower, and the average dust yield higher. This supports a mostly stellar origin for the cosmic dust budget.

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Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies

Cited by 24 publications

References 51 publications

The Deployable Low‐Band Ionosphere and Transient Experiment

The Deployable Low‐Band Ionosphere and Transient Experiment

The LOFAR LBA Sky Survey

Dust destruction and survival in the Cassiopeia A reverse shock

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