Radio Power from Direct-collapse Black Holes

Direct-collapse black holes (DCBHs) forming at z ∼ 20 are currently the leading candidates for the seeds of the first quasars, over 200 of which have now been found at z > 6. Recent studies suggest that DCBHs could be detected in the near-infrared by the James Webb Space Telescope, Euclid, and the Roman Space Telescope. However, new radio telescopes with unprecedented sensitivities such as the Square Kilometre Array (SKA) and the Next-Generation Very Large Array (ngVLA) may open another window on the properties of DCBHs in the coming decade. Here we estimate the radio flux from DCBHs at birth at z = 8–20 with several fundamental planes of black hole accretion. We find that they could be detected at z ∼ 8 by the SKA-FIN all-sky survey. Furthermore, SKA and ngVLA could discover 106–107 M ⊙ BHs out to z ∼ 20, probing the formation pathways of the first quasars in the universe.

Discovery of Rare Dying Radio Galaxies Using MeerKAT

Dying radio galaxies represent a stage of the evolution of active galactic nuclei (AGN), during which the accreting central black hole has switched off and/or falls to such a low level that the plasma outflow can no longer be sustained. When this happens, the radio source undergoes a period of fading, the dying phase, before it disappears completely. We present the study of three potential dying radio sources using the MeerKAT radio telescope: MKT J072851.2-752743, MKT J001940.4-654722, and ACO 548B. The identification as dying radio sources came from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS). We carry out a multi-wavelength analysis of the sources and derive their energetics. The ages of the sources are ∼30–70 Myr, they have magnetic fields of the order of a few μG, and they have relatively low radio power. Their potential optical counterparts are associated with massive galaxies. We show that ACO 548B, previously classified as two peripheral relic radio sources, is a dying radio galaxy. With its good sensitivity and resolution, MeerKAT is an ideal instrument to detect potential dying radio sources, and contribute to the understanding of the evolution of AGN population.

Rancang Bangun Multi Sensor Pengukur Tinggi Muka Air Untuk Lahan Sawah

Abstrak. Penghematan air untuk irigasi permukaan adalah salah satu cara mengurangi efek lingkungan dari budidaya tanaman padi. Dalam sistem AWD(Alternate Wetting Drying) lahan sawah digenangi secara berselang, ketinggian air dari permukaan tanah dimonitor sesuai dengan rekomendasi AWD. Metode ini terbukti dapat mengurangi penggunaan air tanpa mengurangi hasil panen. Perkembangan saat ini pada platform cloud IOT sensor-sensor dapat berhubungan langsung dengan sistem yang menyimpan data dalam kapasitas yang besar, data ini selanjutnya dapat didownload dan diproses. Penelitian ini bertujuan untuk mendesain sistem multi sensor alat pengukur ketinggian permukaan air yang memiliki catu daya yang bersumber pada energi matahari dan dilegkapi dengan baterai Li-Ion dan berbentuk ringkas. Komunikasi dari masing masing sensor ke rangkaian master dilakukan melalui komunikasi radio. Mode hemat daya yang menonaktifkan sensor dan modul radio pada kondisi stanby dapat menghemat pemakaian baterai, tanpa penyinaran matahari baterai dapat bertahan 11,6 hari dibadingkan dengan 3,2 hari pada mode non hemat daya.Tegangan baterai dan pembacaan ketinggian permukaan air diupload ke ThinkSpeak IoT cloud oleh rangkaian master, untuk dianalisa lebih lanjut. Design of Paddy Field Water Level Multi Censor Abstract. Water conservation for field irrigation is an important key to reducing environmental effects from paddy cultivation. In the AWD (Alternate Wet Drying) method, the rice field is alternately flooded and non-flooded, water height is always measured to adjust with AWD recommendation. This method proved for reducing water usage without decreasing yield. With recent development from IoT Cloud platform, sensors can interface directly to cloud systems and store much data so it can be downloaded and processed later. In this study, electronic water height multiple sensors based on infrared technology is equipped with solar panel and Li-Ion battery storage designed with a compact form. Communication from sensors to master done by radio wave. Power saving method which turnoff sensors and radio power in the standby condition can conserve battery to stand the power without sunlight 11.6 days compared to 3.2 days in non-power-saving design. Battery voltage and water level reading from each sensor is uploaded to Think Speaks cloud IoT dashboard, this data can be analyzed later for other purposes.

Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

Galaxy clusters have been found to host a range of diffuse, non-thermal emission components, generally with steep, power law spectra. In this work we report on the detection and follow-up of radio halos, relics, remnant radio galaxies, and other fossil radio plasmas in Southern Sky galaxy clusters using the Murchison Widefield Array and the Australian Square Kilometre Array Pathfinder. We make use of the frequency coverage between the two radio interferometers—from 88 to $\sim\!900$ MHz—to characterise the integrated spectra of these sources within this frequency range. Highlights from the sample include the detection of a double relic system in Abell 3186, a mini-halo in RXC J0137.2–0912, a candidate halo and relic in Abell 3399, and a complex multi-episodic head-tail radio galaxy in Abell 3164. We compare this selection of sources and candidates to the literature sample, finding sources consistent with established radio power–cluster mass scaling relations. Finally, we use the low-frequency integrated spectral index, $\alpha$ ( $S_v \propto v^\alpha$ ), of the detected sample of cluster remnants and fossil sources to compare with samples of known halos, relics, remnants and fossils to investigate a possible link between their electron populations. We find the distributions of $\alpha$ to be consistent with relic and halo emission generated by seed electrons that originated in fossil or remnant sources. However, the present sample sizes are insufficient to rule out other scenarios.

A search for dust and molecular gas in enormous Lyα nebulae at z ≈ 2

Enormous Lyα nebulae, extending over 300−500 kpc around quasars, represent the pinnacle of galaxy and cluster formation. Here we present IRAM Plateau de Bure Interferometer observations of the enormous Lyα nebulae “Slug” (z = 2.282) and “Jackpot” (z = 2.041). Our data reveal bright, synchrotron emission associated with the two radio-loud active galactic nuclei embedded in the targeted nebulae as well as molecular gas, as traced via the CO(3−2) line, in three galaxies (two sources in Slug, and one in Jackpot). All of the CO emission is associated with galaxies detected in their rest-frame UV stellar emission. The total mass in molecular gas of these three galaxies [∼(3 − 5) × 1010 M⊙] is comparable with the total ionized gas mass responsible for the diffuse nebular emission. Our observations place limits on the molecular gas emission in the nebulae: the molecular gas surface density is ΣH2 < 12 − 25 M⊙ pc−2 for the Slug nebula and ΣH2 < 34 − 68 M⊙ pc−2 for the Jackpot nebula. These are consistent with the expected molecular gas surface densities, as predicted via photoionization models of the rest-frame UV line emission in the nebulae, and via Lyα absorption in the Jackpot nebula. Compared to other radio-loud quasars at z > 1 and high-redshift radio-loud galaxies, we do not find any strong trends relating the molecular gas reservoirs, the radio power, and the Lyα luminosities of these systems. The significant step in sensitivity required to achieve a detection of the molecular gas from the nebulae, if present, will require a substantial time investment with JVLA, NOEMA, or ALMA.

MIGHTEE: Are giant radio galaxies more common than we thought?

We report the discovery of two new giant radio galaxies (GRGs) using the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. Both GRGs were found within a ∼1 deg2 region inside the COSMOS field. They have redshifts of z = 0.1656 and z = 0.3363 and physical sizes of 2.4 Mpc and 2.0 Mpc, respectively. Only the cores of these GRGs were clearly visible in previous high resolution VLA observations, since the diffuse emission of the lobes was resolved out. However, the excellent sensitivity and uv coverage of the new MeerKAT telescope allowed this diffuse emission to be detected. The GRGs occupy an unpopulated region of radio power – size parameter space. Based on a recent estimate of the GRG number density, the probability of finding two or more GRGs with such large sizes at z &lt; 0.4 in a ∼1 deg2 field is only 2.7 × 10−6, assuming Poisson statistics. This supports the hypothesis that the prevalence of GRGs has been significantly underestimated in the past due to limited sensitivity to low surface brightness emission. The two GRGs presented here may be the first of a new population to be revealed through surveys like MIGHTEE which provide exquisite sensitivity to diffuse, extended emission.

Method for Detecting Transmission Link Failure in Industrial Wireless Networks

Industrial Wireless Networks have been increasingly employed in industry. In manyindustrial environments device failures can occur. The detection of failures is essential for theproper network operation. This work aims to accomplish link failure detection in an IndustrialWireless Network. A link failure can occur if the radio Power Amplifier presents problems. Ifthe power amplifier does not work properly, asymmetry may occur in communications sincethe Power Amplifier is responsible only for the transmission. It is proposed an algorithm whichperiodically analyses the Receive Signal Level of transmissions and infer whether happening aPower Amplifier fault in some device. The proposed method contributes to the correct diagnosisof network problems since link asymmetry can induce the Network Manager and also the userto understand that healthy devices are not working correctly.