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We present Low-Frequency Array (LOFAR) 143.5-MHz radio observations of flaring activity during 2019 May from the X-ray binary Cygnus X-3. Similar to radio observations of previous outbursts from Cygnus X-3, we find that this source was significantly variable at low frequencies, reaching a maximum flux density of about 5.8 Jy. We compare our LOFAR light curve with contemporaneous observations taken at 1.25 and 2.3 GHz with the RATAN-600 telescope, and at 15 GHz with the Arcminute Microkelvin Imager (AMI) Large Array. The initial 143.5-MHz flux density level, $\sim$2 Jy, is suggested to be the delayed and possibly blended emission from at least some of the flaring activity that had been detected at higher frequencies before our LOFAR observations had begun. There is also evidence of a delay of more than four days between a bright flare that initially peaked on May 6 at 2.3 and 15 GHz, and the corresponding peak ($\gtrsim$ 5.8 Jy) at 143.5 MHz. From the multi-frequency light curves, we estimate the minimum energy and magnetic field required to produce this flare to be roughly 10$^{44}$ erg and 40 mG, respectively, corresponding to a minimum mean power of $\sim$10$^{38}$ erg s$^{-1}$. Additionally, we show that the broadband radio spectrum evolved over the course of our observing campaign; in particular, the two-point spectral index between 143.5 MHz and 1.25 GHz transitioned from being optically thick to optically thin as the flare simultaneously brightened at 143.5 MHz and faded at GHz frequencies., 14 pages, 6 figures, 4 tables, accepted for publication in MNRAS

We present the automated systemfor estimating the parameters of radio sources observed on all available continuum radiometers (two receiving facilities of secondary mirrors No. 1 and No. 2 with a total of 30 radiometers) developed at RATAN-600 radio telescope and put into normal operation. The system is also used for the monitoring of the parameters of the antenna and receiving systems of RATAN-600 radio telescope, which is carried out using current measurements of calibration radio sources.

We report on two giant radio flares of the X-ray binary microquasar Cyg X-3, consisting of a Wolf–Rayet star and probably a black hole. The first flare occurred on 13 September 2016, 2000 days after a previous giant flare in February 2011, as the RATAN-600 radio telescope daily monitoring showed. After 200 days on 1 April 2017, we detected a second giant flare. Both flares are characterized by the increase of the fluxes by almost 2000-times (from 5–10 to 17,000 mJy at 4–11 GHz) during 2–7 days, indicating relativistic bulk motions from the central region of the accretion disk around a black hole. The flaring light curves and spectral evolution of the synchrotron radiation indicate the formation of two relativistic collimated jets from the binaries. Both flares occurred when the source went from hypersoft X-ray states to soft ones, i.e. hard fluxes (Swift/BAT 15–50 keV data) dropped to zero, the soft X-ray fluxes (MAXI 2–10 keV data) staying high, and then later, the binary came back to a hard state. Both similar giant flares indicated the unchanged mechanism of the jets’ formation in Cyg X-3, probably in conditions of strong stellar wind and powerful accretion onto a black hole.

We report the experimental results of a study of the sources of 1/fα type noise (hereafter referred to as 1/f-type noise for the sake of brevity) in a total power radiometer. We find this noise to have two main sources in the radiometer: microwave amplifiers and the square-law diode detector with a Schottky barrier. We present methods for a substantial reduction of 1/f-type noise, which allow total power radiometer measurements to be performed with nominal sensitivity on time scales of up to 10 seconds. The sensitivity of the total power radiometer on time scales up to 100 seconds remains higher than that of a Dicke switched radiometer.

The MARS-3 third-generation matrix radiometric system has been developed, manufactured, and is currently being used in observations within the framework of the “Cosmological Gene” program. The system is based on new hardware components and consists of 16 independent radiometers (32 horns with a step of 20 mm). Each pair of horns is connected to the input of an amplifier unit via a square-loop modulator. The parameters of each radiometer are: central frequency, 30.0 GHz; bandwidth, 5GHz; average noise temperature of the system, 250 K; and a sensitivity of about 5 mK for τ = RC = 1 s.

We report an analysis of the electromagnetic situation at RATAN-600 radio telescope over the 30-year period of operation of the complex of continuum radiometers. We analyze practical methods for mitigating radio interference ranging from the use of anti-interference adapters to incorporating fast digital signal processors into the standard data acquisition system.

Cygnus X-3 (Cyg X-3) is a well-known microquasar producing variable emission at all wavelengths. Cyg X-3 is a prominent X-ray binary producing relativistic jets, and studying its high energy emission is crucial for the understanding of the fundamental acceleration processes in accreting compact objects. Aims. Our goal is to study extreme particle acceleration and {\gamma}-ray production above 100 MeV during special spectral states of Cyg X- 3 usually characterized by a low hard X-ray flux and enhanced soft X-ray states. We observed Cyg X-3 with the AGILE satellite in extended time intervals from 2009 Jun.-Jul., and 2009 Nov.-2010 Jul. We report here the results of the AGILE {\gamma}-ray monitoring of Cyg X-3 as well as the results from extensive multiwavelength campaigns involving radio (RATAN-600, AMI-LA and Mets\"{a}hovi Radio Observatories) and X-ray monitoring data (XTE and Swift). We detect a series of repeated {\gamma}-ray flaring activity from Cyg X-3 that correlate with the soft X-ray states and episodes of decreasing or non-detectable hard X-ray emission. Furthermore, we detect {\gamma}-ray enhanced emission that tends to be associated with radio flares greater than 1 Jy at 15 GHz, confirming a trend already detected in previous observations. The source remained active above 100 MeV for an extended period of time (almost 1.5 months in 2009 Jun.-Jul. and 1 month in 2010 May). We study in detail the short timescale {\gamma}-ray flares that occurred before or near the radio peaks. Our results confirm the transient nature of the extreme particle acceleration from the microquasar Cyg X-3. A series of repeated {\gamma}-ray flares shows correlations with radio and X-ray emission confirming a well established trend of emission. We compare our results with Fermi-LAT and MAGIC TeV observations of Cyg X-3., Comment: 16 pages, 8 figures, 7 tables; A&A (2011)

We report on the radio properties of jets of the following microquasars, as determined from daily multi-frequency monitoring observations with the RATAN-600 radio telescope during 2010–2017: V404 Cyg, SS433, Cyg X-1, GRS1915+105 and LSI+61 ∘ 303. We have detected many giant flares from SS433, a powerful flare from V404 Cyg in June 2015, an active state of Cyg X-1 in 2017 and fifty periodic flares from LSI+61 ∘ 303. We describe the properties of massive ejections based on multi-band (radio, X-ray and γ -ray) studies. The general properties of the light curves are closely connected with the processes of jet formation in microquasars.

Galactic microquasars are binaries with a neutron star or stellar-mass black hole accreting gas from a companion star. They can accelerate particles to relativistic energies and emit radio flares, but the mechanism of jet energization is not known. A survey of the Cygnus region between mid-2007 and mid-2009 has detected four major γ-ray flaring episodes with energies over 100 MeV, each lasting 1 or 2 days, emanating from the microquasar Cygnus X-3. There is a clear pattern of temporal correlation between the γ-ray flares and transitional spectral states of radio and X-ray emission. Particle acceleration occurred a few days before radio jet ejections for two of the flares, suggesting that jet formation involves the production of highly energetic particles. Super-massive black holes in active galaxies can accelerate particles to relativistic energies, producing jets with associated γ-ray emission. Galactic 'microquasars' also produce relativistic jets; however, apart from an isolated event detected in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar. Here, a report of four γ-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 illuminates this important problem. Super-massive black holes in active galaxies can accelerate particles to relativistic energies1, producing jets with associated γ-ray emission. Galactic ‘microquasars’, which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares2. Apart from an isolated event detected3 in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four γ-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary4,5,6 that sporadically produces radio jets7,8,9). There is a clear pattern of temporal correlations between the γ-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

Most of the transient sources that are detected in the gamma-ray sky are produced by extragalactic gamma-ray bursts (GRBs). However, it is known that there are some other astronomical objects that can produce high-energy bursts within the Milky Way. SWIFT J195509+261406, just one degree off the Galactic plane, is one of them. It was discovered on the 10th July 2007 by the Swift satellite and was since then observable for a period of a fortnight. During this time SWIFT J195509+261406 experimented dramatic flaring activity that could be observed in near infrared, optical and X-rays. We gathered multi-wavelength observations of SWIFT J195509+261406 including optical, near infrared, millimeter and radio observations. Our dataset covers the time from 1 min after the burst onset to more than 4 months later. Following the initial burst in the gamma-ray band, we recorded more than 40 flaring episodes in the optical bands (reaching up to I c ∼ 15) over a time span of 3 days, plus a faint infrared flare that was observed at late times. After this time, the source slowly faded away until it became undetectable. Using the observations compiled in this work we propose that this source is part of the magnetar family, linking soft gamma-ray repeaters and anomalous X-ray pulsars to dim isolated neutron stars.

This work is based on observations carried out with the 0.3-m robotic telescope at the Spanish BOOTES-2 astronomical station of the Estación Experimental de La Mayora (CSIC), the 0.4-m WATCHER telescope operated by UCD at Boyden Observatory (South Africa), the 0.8-m IAC telescope at the Spanish Observatorio de Izaña of the Instituto de Astrofísica de Canarias (IAC), the 1.2-m Mercator telescope operated by the Flemish Community at the Spanish Observatorio del Roque de los Muchachos of the IAC, the 1.34-m telescope at the Tautenburg Observatory (Germany), the 1.5-m OSN telescope at the Spanish Observatorio de Sierra Nevada of the Instituto de Astrofísica de Andalucía (CSIC), the 6.0-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences, the 8.2-m VLT telescope of the European Southern Observatory at Paranal (Chile), the IRAM 30-m and Plateau de Bure Telescopes and the 100-m telescope of the Max-Planck-Institut für Radioastronomie at Effelsberg (Germany). IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain)., 4 pages, 4 figures.-- ArXiv pre-print version available at: http://arxiv.org/abs/0809.4231., Magnetars are young neutron stars with very strong magnetic fields of the order of 1014-1015G. They are detected in our Galaxy either as soft γ-ray repeaters or anomalous X-ray pulsars. Soft γ-ray repeaters are a rare type of γ-ray transient sources that are occasionally detected as bursters in the high-energy sky. No optical counterpart to the γ-ray flares or the quiescent source has yet been identified. Here we report multi-wavelength observations of a puzzling source, SWIFT J195509+261406. We detected more than 40 flaring episodes in the optical band over a time span of three days, and a faint infrared flare 11days later, after which the source returned to quiescence. Our radio observations confirm a Galactic nature and establish a lower distance limit of ~3.7kpc. We suggest that SWIFT J195509+261406 could be an isolated magnetar whose bursting activity has been detected at optical wavelengths, and for which the long-term X-ray emission is short-lived. In this case, a new manifestation of magnetar activity has been recorded and we can consider SWIFT J195509+261406 to be a link between the `persistent' soft γ-ray repeaters/anomalous X-ray pulsars and dim isolated neutron stars., D.A.K. and S.K. acknowledge financial support by DFG and D.P.R. from Junta de Andalucía. L.H. acknowledges support from IRCSET and SFI. R.H. acknowledges support from PECs and GACR. This work was partially supported by the Spanish Ministry of Science and Innovation.

We discuss the results of the monitoring programs of the X-ray binaries with relativistic jets studies. We carried out a multi-frequency (1-30 GHz) daily monitoring of the radio flux variability of the microquasars SS433, GRS1915+105, V4641 Sgr and Cyg X-3 with RATAN-600 radio telescope during the recent sets in 2002-2006. We detected a lot of bright short-time flares from GRS 1915+105 which could be associated with active X-ray events. In 2004 we have detected two flares from V4641 Sgr, which followed after recurrent X-ray activity of the transient. From September 2005 to May 2006 and then in July we have daily measured flux densities from Cyg X-3. In January 2006 we detected a drop down of its quiescent fluxes (from 100 to ~20 mJy), then the 1Jy-flare was detected on 2 February 2006 after 18 days of quenched radio emission. The daily spectra of the flare in the maximum were flat from 2 to 110 GHz, using the quasi-simultaneous observations at 110 GHz with the RT45m telescope and the NMA millimeter array of the Nobeyama Radio Observatory in Japan. Several bright radio flaring events (1-15 Jy) followed during the continuing state of very variable and intensive 1-12 keV X-ray emission (~0.5 Crab), which was monitored in the RXTE ASM program. We discuss the various spectral and temporal characteristics of the light curves from the microquasars. Thus we conclude that monitoring of the flaring radio emission is a good tracer of jet activity X-ray binaries., Comment: Proceedings VI Microquasar Workshop: Microquasars and beyond, Sept 18-22 2006, Como, Italy, eds: T. Belloni et al., 10 pages, 9 figures, Published online at http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=33

It is shown that the “spinning dust” component does not prevent observation of the CMB anysotropy at high l, values, as well as observation of the CMB polarization at scales which are the most interesting (l=1000). These results were obtained with the 600-meter reflector RATAN-600, equipped with a multi-frequency feed array with an angular resolution up to 0.1×1 arcmin and with a temperature resolution below 100 μK.

We report about the multi-frequency (1–30 GHz) daily monitoring of the radio flux variability of the three microquasars: SS433, GRS1915+105 and Cyg X-3 during 2005–2006. After a quiescent radio emission we have detected a drop down of the fluxes (∼20 mJy) from Cyg X-3, a sign of the following bright flare, and indeed a 1 Jy flare was detected on 2 February 2006 after 18 days of quenched radio emission. The daily spectra of the flare in the maximum was found flat from 2 to 110 GHz, using the quasi-simultaneous observations at 109 GHz with the RT45m telescope and the NMA millimeter array of Nobeyama Radio Observatory in Japan. Several bright radio flaring events (1–15 Jy) followed during the state of highly variable and intense 1–12 keV X-ray emission (∼0.5 Crab), monitored in the RXTE ASM program. We discussed various spectral and temporal characteristics of the detected 180 day light curves from three microquasars in comparison with the Rossi XTE ASM data.

We present new limits on the small scale 3K emission anisotropy. At the scales of 1° ÷ 3.°3 all 7 harmonics have at λ = 7.6cm amplitudes below 10-5 in ΔT/T. At l from 6.1 103 to 17.5 103 (rad -1) scale this limit is about 2.8 10-4 at a wavelength of 2.7cm and may be fully explained by a discrete source contribution.The low baryonic content of the Universe and present limit on ΔT/T at the horizon scale suggest that (ΔM/M)gravitating ≪ (ΔM/M)baryonic. We speculate that 3K anisotropy measurements demonstrate a) the existence of the dark matter, b) the nonbaryonic nature of this dark matter and c) that the spatial distribution of this matter is much more homogeneous than that of the visible one.

Los Alamos National Laboratory;NASA Goddard Space Flight Center;Universities Space Research Association;Center for Space Science and Exploration;Swift Satellite Mission Santa Fe Conference on Gamma-Ray Bursts 2007, GRB 2007 --5 November 2007 through 9 November 2007 -- Santa Fe, NM -- The majority of bright gamma-ray transients that we observe in the sky, are produced by extragalactic gamma-ray bursts (GRBs). However, we know that there are other kinds of sources that can produce intense bursts of high-energy photons within our own Galaxy. GRB 070610/Swift J195509+261406, being just 1 degree away from the Galactic plane, is one of these sources and presents a peculiar behavior, as it shows strong flaring activity that has been observed in the optical and near infrared. We have gathered multi-wavelength observations of GRB 070610 including optical, near infrared, millimeter and radio observations. Our dataset covers the time from 1 minute after the burst onset to more than 4 months later. Following the burst in the gamma-ray band, the source displayed more than 40 flaring episodes in the optical bands (reaching up to Ic~15) over a time span of three days, plus a faint infrared flare that was observed at late times. After this time, the source slowly faded away until it became undetectable. © 2008 American Institute of Physics.