High Frequency Radio Emissions Research Articles

The Nature of the IMBH Candidate CXO J133815.6+043255: High-frequency Radio Emission

The ultraluminous X-ray source CXO J133815.6+043255 is a strong candidate for a bona fide intermediate-mass black hole residing in the outskirts of NGC 5252. We present 22 GHz radio observations of this source obtained serendipitously in an ongoing high-frequency imaging survey of radio-quiet Active Galactic Nuclei (AGNs), and use this new data point to construct the broadband radio spectral energy distribution (SED). We find that the SED exhibits a spectral slope of α = −0.66 ± 0.02, consistent with a steep spectrum from optically thin synchrotron emission from an unresolved jet. We also find that the L R/L X ratio is approximately 10−3, inconsistent with radio-quiet AGN and many ULXs but consistent with low-luminosity AGN and radio-loud quasars. Together, these observations support the conclusion that CXO J133815.6+043255 is an intermediate-mass black hole producing a low-mass analog of radio jets seen in classical quasars.

The danger of ball lightning

Ball lightning in close contact with living beings can strike them with electric current or high-frequency radio emission. The current, passing through the surface of the skin, can cause it to burn. The entry of current into the region of the heart or the respiratory center of the brain can lead to death. High-frequency radio emission from ball lightning occurs in the wavelength range of 1-10 cm and can be absorbed by liquid water. When ball lightning comes into close contact with the body, blood heating and muscle rupture can occur. Cases of the indicated action of ball lightning on people are given. It is shown that the charge of ball lightning can be kept in a shell consisting of polarized water molecules. The reason for the generation of electromagnetic radiation of ball lightning is the cyclic movement of electrons in closed orbits. The radiation power sharply increases when the uniform distribution of electrons along the orbit is violated. It had been proven that dashed traces that appear on photographic films during electrical discharges in water are created by the action of multiply charged clusters having the structure of ball lightning. These clusters can penetrate the skin into living organisms and remain in them for a long time. The biological effect of these clusters has not yet been studied, but there is evidence that they are hazardous to health (causing cancer and liver damage).

Some Results of Photometric Measurements of Ionospheric Artificial Airglow at 557.7 and 630 nm Lines of Atomic Oxygen Caused by High-Frequency Radio Emission of the SURA Facility during Development of Sporadic E Layer

The results of analysis of the experimental data collected on 5 September 2021 on 557.7 and 630 nm artificial airglow of the ionosphere induced by powerful HF radio waves at the SURA facility are presented. For optical measurements, a photometric suite located directly next to the SURA facility was used. Fast variations in the atmospheric emission intensity at 557.7 nm, 630 nm, and 391.4 nm with a three-channel photometer and spatial–temporal variations in the 557.7 nm with a CCD camera were measured. An ionospherically reflected pump wave and the stimulated electromagnetic emission (SEE) were recorded. Background ionospheric conditions were registered with ionosonde. For the first time, an increase in the 557.7 nm emission intensity induced by the SURA facility radiation was found concurrently with a partial blocking ionosphere in the F-region and suppression HF-induced phenomena in the F-region (the 630 nm airglow increase and SEE generation, powerful radio wave anomalous absorption) during the sporadic E-layer (Es) development. Additionally, we managed to obtain images showing moving spots of the SURA-induced 557.7 nm emission increased intensity at the Es layer heights.

Electromagnetic emissions in the MHz and GHz frequency ranges driven by the streamer formation processes.

We provide comprehensive data on the spectral and temporal characteristics of low-frequency (LF) (MHz) and high-frequency (HF) (GHz) radio emissions and investigate their correlation with the streamer formation. We show that the propagation of streamers from the cathode is accompanied only by the LF radio emission (10-150MHz). In contrast, the HF radio emission (1-4GHz) arises during the travel of counterstreamers from the anode, which is also indicated by radio interferometric measurements. The power of the LF radio emission sharply increases almost synchronously with that of the HF radio emission. We find that the HF radio emission has a complex spectral and temporal structure and appears as multiple short (less than 1ns) bursts characterized by various frequency components, existing in subnanosecond time intervals.

Radiation electric field produced by the lightning leader formation in a thundercloud: Observations and modeling

Recently for a number of thunderstorm systems in different regions of the planet there have been reports of observations of high frequency radio emission with duration varying from several to more than one hundred of milliseconds which may both be isolated or precede the lightning initiation. There is a consensus that this radiation originates from continuous sequences of short-duration discharges that randomly fill the areas of strong electric field between the main negative and the upper positive charge regions. But the concrete physical mechanism of discharge activity evolution and its contribution to the lightning leader formation remain unclear. To answer these questions several hypotheses were proposed, among which the runaway breakdown and fast positive discharge can be accentuated. In this study, we present another explanation which is based on comparison of experimental data of thundercloud radio activity obtained in the Nizhny Novgorod region of the Russian Federation on May 15, 2019 with the use of a wide band radio interferometer with the results of our numerical simulation of the lightning leader formation in the active part of a thundercloud. It is shown that the observed intense electric field bursts can originate from mergers of two or more streamer systems or bipolar leaders with lengths ranging from several to several tens of meters. In the framework of our approach, the sequence of such mergers can, under certain conditions, result in the self-sustaining leader channel formation finishing the lightning initiation process.

Mesosphere Ozone and the Lower Ionosphere under Plasma Disturbance by Powerful High-Frequency Radio Emission

We present the results of experiments on the Earth’s lower ionosphere at mesospheric heights by creating artificial periodic irregularities (APIs) of the ionospheric plasma and simultaneous measurement of the atmospheric emission spectrum in the ozone line by ground-based microwave radiometry when the ionosphere was disturbed by powerful high-frequency radio emission from the midlatitude SURA heating facility (56.15° N; 46.11° E). The diagnostics of the ionosphere was carried out on the basis of measuring amplitudes and phases of signals scattered by periodic irregularities in the altitude range of 50–130 km. For each heating session lasting 30 min, two ozone spectra were measured. These spectra were compared with the measured spectra the periods when heating was turned off. During the heating session of the ionosphere, a decrease in the intensity of the microwave radiation of the atmosphere in the ozone line was observed. The lower ionosphere was characterized by intense dynamics. Rapid variations in the amplitude of the scattered signal and the relaxation time of artificial periodic irregularities were observed. The velocity of a regular vertical movement in the D-region of the ionosphere constantly varied direction with average minute values up to 4–5 m/s. We assume the decrease in the ozone emission spectrum at the altitude of 60 km can be explained by an increase in the coefficient of electron attachment to oxygen molecules during heating sessions. The lower boundary of the region enriched with atomic oxygen was estimated from the height profile of the API relaxation time.

Evaluating Chlorophyll and Nitrogen Production in Edible Plant Sources Grown Under 5 Gigahertz Radiofrequency Radiation Emissions

By 2022 the demand for constant connectivity to high speed wireless communication networks is predicted to skyrocket with over 12 billion mobile devices and almost half a billion public Wi‐Fi hot spots. Both 5th generation (5G) cellular networks and current IEEE 802.11 Wi‐Fi can transmit radiofrequencies in the 5 Giga Hertz (5 GHz) range. Higher frequencies, such as those in the 5 GHz range, have been shown to be more harmful to humans and biological systems than lower frequencies. Although not well understood, frequencies generated in this range by newly established 5G cellular networks, and common Wi‐Fi 5 GHz networks, may pose a danger to biological systems which could have a significant impact on human health.This work looks to examine the effects of 5 GHz radiofrequency radiation on chlorophyll production and nitrogen levels in green leafy plants, in particular spinach. Chlorophyll is the most important intermediate in the conversion of light to organic matter in photosynthesis. Nitrogen is known to be directly proportional to chlorophyll content and is found in high amounts within enzymes, proteins, and thylakoid membranes required for photosynthesis. Spinach is known to have high levels of chlorophyll and has been chosen as the plant for testing. Using a TYS‐B Portable Chlorophyll Meter, chlorophyll and nitrogen levels will be non‐destructively measured over 5 weeks of growth under close bombardment from 5 GHz generated radio emissions in treatment groups and control groups shielded from all radio frequency emissions.If statistical significance suggests chlorophyll and nitrogen levels are decreased between treatment and control groups, further investigation may be warranted to assess the impact on human and plant health. Lower chlorophyll levels could decrease overall group weight and may contribute to a decline in pollinators. Decreased pollinators and lower crop yields could cost consumers billions of dollars in lower availability. As high frequency radio emissions continue to increase across the globe, any information would be available in determining possible dangers from these new technologies.Support or Funding Information• Bridges to Baccalaureate Grant awarded through National Institute of General Medical Sciences, Coconino Community College NIH Grant # 1R25GM102788‐01

Three‐Dimensional Mapping of Lightning‐Produced Ionospheric Reflections

AbstractThe powerful high‐frequency/very high frequency radio emissions that occur during lightning flashes can be used as a signal of opportunity to study the bottom side ionosphere. The lightning emission is bright, broad spectrum, and short in duration, providing an ideal signal of opportunity for making ionograms. This study continues previous work in Obenberger et al. (2018), where the direct line of sight signal from lightning can be cross correlated with megahertz frequency radio telescope observations to reveal ionogram traces created from the reflected lightning signals. This process was further developed to automate production of ionograms made from individual lightning flashes over the course of several hours, as well as create new techniques to detect the lightning signal using the all‐sky‐imaging mode. By using the Long Wavelength Array Sevilleta radio telescope as an interferometer, the point of reflection of the lightning signal for each frequency of the ionogram can be located in the ionosphere, instantaneously revealing density gradients within the ionosphere on minute time scales. We also explore the minimum size stations required for the application of this technique, which we found to be at least 32 antennas.

High-Frequency Radio Emission from Meteors

A model of the processes that explain the intrinsic radio emission from meteors is proposed. A method for solving a self-similar problem of a strong explosion is used to determine certain parameters of the plasma wake dynamics at the initial expansion stages. Calculations show that this plasma expansion stage is responsible for the incoherent and unpolarized radiation from the meteor in the upper layers of the atmosphere. A theoretical estimate of the spectral density of the radio emission flux is obtained within this model, and it coincides with the experimental values. The radiation maximum is in the high-frequency range and strongly depends on the altitude and parameters of the meteor. For example, for the characteristic properties of the atmosphere at an altitude of about 90 km for a meteor with a mass of ~5 × 10–2 kg, the spectral flux is ~2000 W/m2 Hz at ~100 km from the source and the maximum is at ~40–60 MHz. According to the experiment, the radio emission spectrum drops sharply at higher frequencies.

Very High Frequency Radio Emissions Associated With the Production of Terrestrial Gamma‐Ray Flashes

AbstractRecent studies of the close association between terrestrial gamma‐ray flashes (TGFs) production and simultaneous lightning processes have shown that many TGFs are produced during the initial leader of intracloud flashes and that some low‐frequency (LF) radio emissions may directly come from TGF itself. Measurements of any simultaneous very high frequency (VHF) radio emissions would give important insight into any lightning leader dynamics that are associated with TGF generation, and thus, such measurements are needed. Here we report on coordinated observations of TGFs detected simultaneously by Fermi Gamma‐ray Burst Monitor, two VHF lightning mapping arrays, and Duke ground‐based LF radio sensors to investigate more on the close association between TGFs and LF and VHF radio emissions. Three TGFs are analyzed here and confirm previous findings on the close association between TGF generation and lightning processes and, for the first time, provide time‐aligned measurements of the VHF radio signature within a few tens of microseconds of TGF generation. Strong VHF emissions were observed essentially simultaneously with two TGFs and within a few tens of microseconds of a third TGF. Equally importantly, the VHF measurement details indicate that the TGF‐associated emissions are nonimpulsive and extended in time. We conclude that the TGF‐producing process is at least sometimes closely associated with strong VHF emissions, and thus, there may be a link between the generation of TGFs and active lightning streamer dynamics.

The High-frequency Radio Emission of the Galactic Center Magnetar SGR J1745–29 during a Transitional Period

Abstract The origin of the high-frequency radio emission detected from several magnetars is poorly understood. In this paper, we report the ∼ 40 GHz properties of SGR J1745−29 measured using Jansky Very Large Array (JVLA) and Robert C. Byrd Green Bank Telescope (GBT) observations between 2013 October 26 and 2014 May 31. Our analysis of a Q-band (45 GHz) GBT observation on 2014 April 10 resulted in the earliest detection of pulsed radio emission at high frequencies ( ≳ 20 GHz ); we found that the average pulse has a singly peaked profile with width ∼ 75 ms (∼2% of the 3.764 s pulse period) and an average pulsed flux density of ∼100 mJy. We also detected very bright, short ( < 10 ms ) single pulses during ∼70% of this neutron star’s rotations, and the peak flux densities of these bright pulses follow the same log-normal distribution as measured at 8.5 GHz. Additionally, our analysis of contemporaneous JVLA observations suggest that its 41/44 GHz flux density varied between ∼1–4 mJy during this period, with a ∼ 2 × change observed on ∼20 minute timescales during a JVLA observation on 2014 May 10. Such a drastic change over short timescales is inconsistent with the radio emission resulting from a shock powered by the magnetar’s supersonic motion through the surrounding medium, but consistent with pulsed emission generated in its magnetosphere.

Satellite triangulation of thunderstorms, from fading radio fields synchronously recorded on two orthogonal antennas

Single‐satellite observations of lightning radio emissions normally do not independently provide useful thunderstorm location. The scientific value of these radio waveform recordings is greatly enhanced by knowing at least the approximate location of the source thunderstorm. Since the Very High Frequency radio emissions from lightning are always broadband and usually incoherent, radio interferometry is an obvious approach to direction‐finding the source. However, radio‐interferometry requires separated, deployed antennas, and for decametric radio waves, success with interferometric direction‐finding on a satellite has not yet been reported. We describe a method for approximate location of source thunderstorms, using the statistical fading of the received electric field on two orthogonal, but co‐located, antennas. The method is based on previous work geolocating polarized sources, and we show that it can be adapted efficiently to unpolarized radio fields, which constitute the majority of lightning emissions. We implement the method with dual‐antenna radio recordings from the FORTE satellite, and demonstrate its capabilities using a wide variety of radio data.

COMPLEX RADIO SPECTRAL ENERGY DISTRIBUTIONS IN LUMINOUS AND ULTRALUMINOUS INFRARED GALAXIES

We use the Expanded Very Large Array to image radio continuum emission from local luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in 1 GHz windows centered at 4.7, 7.2, 29, and 36 GHz. This allows us to probe the integrated radio spectral energy distribution (SED) of the most energetic galaxies in the local universe. The 4-8 GHz flux densities agree well with previous measurements. They yield spectral indices \alpha \approx -0.67 (where F_\nu \propto \nu^\alpha) with \pm 0.15 (1\sigma) scatter, typical of nonthermal (synchrotron) emission from star-forming galaxies. The contrast of our 4-8 GHz data with literature 1.5 and 8.4 GHz flux densities gives further evidence for curvature of the radio SED of U/LIRGs. The SED appears flatter near \sim 1 GHz than near \sim 6 GHz, suggesting significant optical depth effects at the lower frequencies. The high frequency (28-37 GHz) flux densities are low compared to extrapolations from the 4-8 GHz data. We confirm and extend to higher frequency a previously observed deficit of high frequency radio emission for luminous starburst galaxies.

Comparison of Narrow Bipolar Events with Ordinary Lightning as Proxies for Severe Convection

Abstract Narrow bipolar events (NBEs) are a recently studied intracloud electrical-discharge process. It is speculated that an NBE is instigated by the extensive atmospheric shower of an energetic cosmic ray. NBEs cause significant relaxation of the charge separation within the electrified cloud in a short time, on the order of 10 μs. The current flow causes radiation of a distinctive “bipolar” low-frequency/very low frequency signal that can be recorded at locations on earth up to thousands of kilometers from the source. NBEs are preceded/accompanied by the most powerful very high frequency radio emissions seen in any kind of lightning. These intense pulsed radio emissions have been routinely detected with satellite-borne radio receivers in space. Owing to their easy detection and recognition, NBEs might be a useful remote sensing proxy for space-based global, near–real time remote sensing. However, in order for that potential to be realized, NBEs must be shown to be associated, as is ordinary lightning, with severe tropospheric convection, rather than to be just a curiosity of cosmic-ray–atmosphere interactions. This question is addressed with a detailed comparison of NBEs and ordinary lightning using a ground-based lightning-transient research facility that records signals from both ordinary lightning and NBEs, the Los Alamos Sferic-waveform Array (LASA), based in Florida. First, the data from LASA are internally compared to examine the relationship of NBEs and ordinary lightning in both position and time. Second, the relationship of both NBEs and ordinary lightning to simultaneous infrared cloud imagery is examined [from the Geostationary Operational Environmental Satellite-East (GOES-East)] in order to infer the relative affinities of NBEs and ordinary lightning for cloud signatures that are consistent with severe convection.

Radio Spectrum of Maffei 2

THE conclusion that Maffei 1 and 2 are previously unrecognized nearby galaxies1 has aroused considerable interest; a positive detection of high frequency radio emission from Maffei 2 has been reported2,3 as also has a null result in the direction of Maffei 1 (ref. 4). Here we report observations at a much lower frequency; they are results obtained during a radio survey5 using the Cambridge 178 MHz pencil-beam synthesis instrument, with beam size 18′.5 × 23′.4.