Spectral index of the diffuse radio background between 50 and 100 MHz

Mozdzen, Thomas J.; Mahesh, Nivedita; Monsalve, Raul A.; Rogers, A. E. E.; Bowman, Judd D.

doi:10.1093/mnras/sty3410

Cited by 59 publications

(62 citation statements)

References 66 publications

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“…It was found during the station sensitivity studies that applying a single calibration (from the transiting Sun) to long observations may result in flux density errors of the order of 20-30%. Similar variations were identified in the amplitudes of calibration solutions over many hours of calibration using lowfrequency all-sky sky models, such as the sky image at 408 MHz (Haslam et al 1982), the so-called 'Haslam map', scaled down to low frequencies using a spectral index of −2.55 (Mozdzen et al 2019) or Global Sky Model (de Oliveira-Costa et al 2008). These variations of amplitudes of calibration solutions have been found to be mainly due to diurnal changes in ambient temperature.…”

Section: Flux Calibrationmentioning

confidence: 72%

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Sokołowski

Wayth

Price

et al. 2021

Publ. Astron. Soc. Aust.

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We present the first Southern-Hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of the low-frequency component of the Square Kilometre Array (SKA-Low). Since its deployment, the system has been used for real-time monitoring of the recorded commissioning data. Additionally, a transient searching algorithm has been executed on the resulting all-sky images. It uses a difference imaging technique to enable identification of a wide variety of transient classes, ranging from human-made radio-frequency interference to genuine astrophysical events. Observations at the frequency 159.375 MHz and higher in a single coarse channel ( $\approx$ 0.926 MHz) were made with 2 s time resolution, and multiple nights were analysed generating thousands of images. Despite having modest sensitivity ( $\sim$ few Jy beam–1), using a single coarse channel and 2-s imaging, the system was able to detect multiple bright transients from PSR B0950+08, proving that it can be used to detect bright transients of an astrophysical origin. The unusual, extreme activity of the pulsar PSR B0950+08 (maximum flux density $\sim$ 155 Jy beam–1) was initially detected in a ‘blind’ search in the 2020 April 10/11 data and later assigned to this specific pulsar. The limitations of our data, however, prevent us from making firm conclusions of the effect being due to a combination of refractive and diffractive scintillation or intrinsic emission mechanisms. The system can routinely collect data over many days without interruptions; the large amount of recorded data at 159.375 and 229.6875 MHz allowed us to determine a preliminary transient surface density upper limit of $1.32 \times 10^{-9} \text{deg}^{-2}$ for a timescale and limiting flux density of 2 s and 42 Jy, respectively. In the future, we plan to extend the observing bandwidth to tens of MHz and improve time resolution to tens of milliseconds in order to increase the sensitivity and enable detections of fast radio bursts below 300 MHz.

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Section: Flux Calibrationmentioning

confidence: 72%

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Sokołowski

Wayth

Price

et al. 2021

Publ. Astron. Soc. Aust.

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“…At MHz frequencies the synchrotron spectrum is flatter [49,132]. Typical values at mid and high Galactic latitudes are −2.59 < −β < −2.54 between 50 and 100 MHz [96] and −2.62 < −β < −2.60 between 90 and 190 MHz [95], as measured by the EDGES instrument.…”

Section: Galactic Foregrounds In Total Intensitymentioning

confidence: 89%

Foregrounds and Their Mitigation

Chapman¹,

Jelić²

2019

The Cosmic 21-Cm Revolution

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The low-frequency radio sky is dominated by the diffuse synchrotron emission of our Galaxy and extragalactic radio sources related to Active Galactic Nuclei and star-forming galaxies. This foreground emission is much brighter than the cosmological 21 cm emission from the Cosmic Dawn and Epoch of Reionization. Studying the physical properties of the foregrounds is therefore of fundamental importance for their mitigation in the cosmological 21 cm experiments. This chapter gives a comprehensive overview of the foregrounds and our current state-of-the-art knowledge about their mitigation.

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“…PyGDSM provides sky maps built on four different references: LFSS [12], GSM2008 [13], GSM2016 [14] and Haslam [15,16] with settable spectral index. For the Haslam map we set the spectral index to −2.52 [17]. The sky temperature map differences are illustrated in Fig.…”

Section: Simulated Galactic Signalmentioning

confidence: 99%

First results from the AugerPrime Radio Detector

Fodran¹,

Abreu²,

Aglietta³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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The Pierre Auger Observatory investigates the properties of the highest-energy cosmic rays with unprecedented precision. The aim of the AugerPrime upgrade is to improve the sensitivity to the primary particle type. The improved mass sensitivity is the key to exploring the origin of the highest-energy particles in the Universe. The purpose of the Radio Detector (as part of AugerPrime) is to extend the sensitivity of the mass measurements to zenith angles in the range of 65°and 85°. A radio antenna, sensitive in two polarization directions and covering a bandwidth from 30 to 80 MHz, will be added to each of the 1661 surface detector stations over the full 3000 km 2 area, forming the world's largest radio array for the detection of cosmic particles. Since November 2019, an engineering array, comprised of ten stations has been installed in the field. The radio antennas are calibrated using the Galactic (diffuse) emission. The sidereal modulation of this signal is monitored continuously and is used to obtain an end-to-end calibration from the receiving antenna to the ADC in the read-out electronics. The calibration method and first results will be presented. The engineering array is also fully integrated in the data acquisition of the Observatory and records air showers regularly. The first air showers detected simultaneously with the water-Cherenkov detectors and the Radio Detectors will be presented. Simulations of the detected showers, based on the reconstructed quantities, have been conducted with CORSIKA/CoREAS. A comparison of the measured radio signals with those predicted by simulations exhibits satisfying agreement.

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Spectral index of the diffuse radio background between 50 and 100 MHz

Cited by 59 publications

References 66 publications

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Foregrounds and Their Mitigation

First results from the AugerPrime Radio Detector

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