Search of exoplanetary radio signals in the presence of strong interference: enhancing sensitivity by data accumulation

Ryabov, V. B.; Zarka, Philippe; Ryabov, B. P.

doi:10.1016/j.pss.2004.09.019

Cited by 45 publications

(42 citation statements)

References 11 publications

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“…Lazio et al 2004;Grießmeier et al 2007b;. Despite repeated attempts, there have been no confirmed exoplanetary radio emission detections to date E-mail: wcvs@st-andrews.ac.uk (Bastian et al 2000;Ryabov et al 2004;Lazio & Farrell 2007;Smith et al 2009;Lecavelier Des Etangs et al 2009Hallinan et al 2013;Sirothia et al 2014). Bastian et al (2000) offer several possible reasons for the lack of detection.…”

Section: Introductionmentioning

confidence: 99%

Time-scales of close-in exoplanet radio emission variability

See

Jardine

Farès

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and τ Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetised hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is co-rotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of τ Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of the magnetic cycle. The lack of radio variability on the synodic period at τ Boo b is not predicted by previous radio emission models, which do not account for the co-rotation of the interplanetary plasma at small distances from the star.

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Section: Introductionmentioning

confidence: 99%

Time-scales of close-in exoplanet radio emission variability

See

Jardine

Farès

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…Automated RFI flagging pipelines can solve this problem (Flöer et al 2010;Offringa et al 2010b). Alternative RFI strategies might be required for the detection of transients (Ryabov et al 2004;Kocz et al 2012).…”

Section: Introductionmentioning

confidence: 99%

The LOFAR radio environment

Offringa

Bruyn

Zaroubi

et al. 2012

A&A

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Aims. This paper discusses the spectral occupancy for performing radio astronomy with the Low-Frequency Array (LOFAR), with a focus on imaging observations. Methods. We have analysed the radio-frequency interference (RFI) situation in two 24-h surveys with Dutch LOFAR stations, covering 30−78 MHz with low-band antennas and 115-163 MHz with high-band antennas. This is a subset of the full frequency range of LOFAR. The surveys have been observed with a 0.76 kHz/1 s resolution. Results. We measured the RFI occupancy in the low and high frequency sets to be 1.8% and 3.2% respectively. These values are found to be representative values for the LOFAR radio environment. Between day and night, there is no significant difference in the radio environment. We find that lowering the current observational time and frequency resolutions of LOFAR results in a slight loss of flagging accuracy. At LOFAR's nominal resolution of 0.76 kHz and 1 s, the false-positives rate is about 0.5%. This rate increases approximately linearly when decreasing the data frequency resolution. Conclusions. Currently, by using an automated RFI detection strategy, the LOFAR radio environment poses no perceivable problems for sensitive observing. It remains to be seen if this is still true for very deep observations that integrate over tens of nights, but the situation looks promising. Reasons for the low impact of RFI are the high spectral and time resolution of LOFAR; accurate detection methods; strong filters and high receiver linearity; and the proximity of the antennas to the ground. We discuss some strategies that can be used once low-level RFI starts to become apparent. It is important that the frequency range of LOFAR remains free of broadband interference, such as DAB stations and windmills.

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“…A straightforward way of overcoming this difficulty was implemented in the described device, which consists in building a baseband receiver with a high linear dynamic range using high-resolution analog to digital conversion (ADC). Efficient interference suppression can be performed at later stages by applying RFI mitigation techniques (usually in the spectral domain), i.e., at the post-processing stage Rosolen et al 1999;Weber et al 2005;Ryabov et al 2004b). The design of the receiver/spectrometer described in this paper has thus focused on achieving the highest dynamic range and sensitivity, sufficient for recording weak radio sources notwithstanding strong in-band interference.…”

Section: Receiver Technical Requirements and Specificationsmentioning

confidence: 99%

“…In 2005−2008, the receiver was tested for a frequency bandwidth of 33 MHz at A&A 510, A16 (2010) -Power spectrum -Coherence (Cross-correlation spectrum) Digital frequency down conversion Optional the world's largest decameter radio telescope UTR-2 (Ukraine) (Braude et al 1978;Ryabov et al 2004a;Lecacheux et al 2004). A series of observations were performed that targeted strong as well as comparatively weak (or even yet undetected) sources of radio emission known to exist in the decameter waveband, such as Jupiter Hess et al 2009), Saturn (Griessmeier et al 2008), exoplanets (Zarka et al 2001;Ryabov et al 2004b;Weber et al 2007), radio pulsars, and the Sun (Briand et al 2008;Melnik et al 2008). …”

Section: Introductionmentioning

confidence: 99%

A low-noise, high-dynamic-range, digital receiver for radio astronomy applications: an efficient solution for observing radio-bursts from Jupiter, the Sun, pulsars, and other astrophysical plasmas below 30 MHz

Ryabov¹,

Vavriv

Zarka

et al. 2010

A&A

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A new two-channel digital receiver that can be used for observing both stationary and sporadic radio sources in the decameter wave band is presented. Current implementation of the device operating at the sampling frequency of 66 MHz is described in detail, including the regimes of waveform capture, spectrogram analysis, and coherence analysis (cross covariance between the two inputs). Various issues pertaining to observational methods in the decameter waveband affected significantly by man-made interferences have been taken into account in the receiver design, as well as in the architecture of the interactive software that controls the receiver parameters in real time. Two examples of using the receiver with the UTR-2 array (Ukraine) are reported: S-bursts from Jupiter and low-frequency wide-band single pulses from the pulsar PSR0809+74

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Search of exoplanetary radio signals in the presence of strong interference: enhancing sensitivity by data accumulation

Cited by 45 publications

References 11 publications

Time-scales of close-in exoplanet radio emission variability

Time-scales of close-in exoplanet radio emission variability

The LOFAR radio environment

A low-noise, high-dynamic-range, digital receiver for radio astronomy applications: an efficient solution for observing radio-bursts from Jupiter, the Sun, pulsars, and other astrophysical plasmas below 30 MHz

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