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We investigated the radio spectra of two magnetars, PSR J1622$-$4950 and 1E 1547.0$-$5408, using observations from the Australia Telescope Compact Array and the Atacama Large Millimeter/submillimeter Array taken in 2017. Our observations of PSR J1622$-$4950 show a steep spectrum with a spectral index of $-$1.3 $\pm$ 0.2 in the range of 5.5-45 GHz during its re-activating X-ray outburst in 2017. By comparing the data taken at different epochs, we found significant enhancement in the radio flux density. The spectrum of 1E 1547.0$-$5408 was inverted in the range of 43-95 GHz, suggesting a spectral peak at a few hundred gigahertz. Moreover, we obtained the X-ray and radio data of radio magnetars, PSR J1622$-$4950 and SGR J1745$-$2900, from literature and found two interesting properties. First, radio emission is known to be associated with X-ray outburst but has different evolution. We further found that the rising time of the radio emission is much longer than that of the X-ray during the outburst. Second, the radio magnetars may have double peak spectra at a few GHz and a few hundred GHz. This could indicate that the emission mechanism is different in the cm and the sub-mm bands. These two phenomenons could provide a hint to understand the origin of radio emission and its connection with the X-ray properties., 7 pages, 4 figures, to be published in MNRAS

We report the findings of an upgraded Giant Metrewave Radio Telescope (uGMRT) observing campaign for FRB 180916.J0158+65, which was recently found to show a 16.35-d periodicity of its active cycle. We observed the source at 550–750 MHz for ∼2 h during each of three successive cycles at the peak of its expected active period. We find 0, 12 and 3 bursts, respectively, implying a highly variable bursting rate even within the active phase. We consistently detect faint bursts with spectral energies only an order of magnitude higher than the Galactic burst source SGR 1935+2154. The times of arrival of the detected bursts rule out many possible aliased solutions, strengthening the findings of the 16.35-d periodicity. A periodicity search over a short time-scale returned no highly significant candidates. Two of the beamformer-detected bursts were bright enough to be clearly detected in the imaging data, achieving subarcsec localization, and proving to be a proof-of-concept for FRB imaging with the GMRT. We provide a 3σ upper limit of the persistent radio flux density at 650 MHz of 66 μJy, which, combined with the European VLBI Network and Very Large Array limits at 1.6 GHz, further constrains any potential radio counterpart. These results demonstrate the power of the uGMRT for providing targeted observations to detect and localize known repeating FRBs.

We assemble a large set of 2-10 GHz radio flux density measurements and upper limits of 294 different supernovae (SNe), from the literature and our own and archival data. Only 31% of the SNe were detected. We characterize the SN lightcurves near the peak using a two-parameter model, with $t_{\rm pk}$ being the time to rise to a peak and $L_{\rm pk}$ the spectral luminosity at that peak. Over all SNe in our sample at $D, Accepted for publication in the Astrophysical Journal 15 Figures, 4 Tables; Full version of Table 1 in ancillary files. Minor revisions only from version 1

For around 50 years, a solar flare is among the activities of the Sun that has been evaluated and observed by scientists. The origin of the solar flare is from the sunspot associated with a solar burst. The solar burst can be break into 5 types. Long duration solar bursts have been investigated in this study. There are 15 selected dates that have been chosen from 2019 until 2020. Radio flux and sunspot numbers affiliated with long-duration solar bursts have been analyzed in this paper. As a result, the longest and the shortest solar burst that has been recorded is 535 minutes on 14/04/19 and 36 minutes on 21/03/19 respectively. The Sun is very important to be consistently observed because in rare cases, the flare is very strong and can affect the Earth’s magnetosphere.

We report the discovery of a double-double radio source (DDRS) J0028+0035. We observed it with LOFAR, GMRT, and the VLA. By combining our observational data with those from the literature, we gathered an appreciable set of radio flux density measurements covering the range from 74 MHz to 14 GHz. This enabled us to carry out an extensive review of physical properties of the source and its dynamical evolution analysis. In particular, we found that, while the age of the large-scale outer lobes is about 245 Myr, the renewal of the jet activity, which is directly responsible for the double-double structure, took place only about 3.6 Myr ago after about 11 Myr long period of quiescence. Another important property typical for DDRSs and also present here is that the injection spectral indices for the inner and the outer pair of lobes are similar. The jet powers in J0028+0035 are similar too. Both these circumstances support our inference that it is, in fact, a DDRS which was not recognized as such so far because of the presence of a coincident compact object close to the inner double so that the centre of J0028+0035 is apparently a triple., 14 pages, 8 figures, matches the version published in MNRAS

Some recent studies have examined the gamma-ray flux profile of our Galaxy to determine the signal of dark matter annihilation. However, the results are controversial and no confirmation is obtained. In this article, we study the radio flux density profile of the M31 galaxy and show that it could manifest a possible signal of dark matter annihilation. By comparing the likelihoods between the archival observed radio flux density profile data and the predicted radio flux density profile contributed by dark matter and stellar emission, we can constrain the relevant dark matter parameters. Specifically, for the thermal annihilation cross section via the $b\bar{b}$ channel, the best-fit value of dark matter mass is $\sim 30$ GeV, which is consistent with the results of many recent studies. We expect that this method would become another useful way to constrain dark matter, which is complementary to the traditional radio analyses and the other indirect detections., Accepted in MNRAS

Thanks to recurrent observations of the black hole binary Cyg X-1 carried out over 15 years the INTEGRAL satellite has collected the largest data set in the hard X-ray band for this source. We have analyzed these data, complemented by data collected by other X-ray satellites and radio flux at 15 GHz. To characterize the spectral and variability properties of the system we have examined parameters such as the hard X-ray flux, photon index and fractional variability. Our main result is that the 2D distribution of the photon index and flux determined for the 22-100 keV band forms six clusters. This result, interpreted within the Comptonization scenario as the dominant process responsible for the hard X-ray emission, leads to a conclusion that the hot plasma in Cyg X-1 takes the form of six specific geometries. The distinct character of each of these plasma states is reinforced by their different X-ray and radio variability patterns. In particular, the hardest and softest plasma states show no short-term flux - photon index correlation typical for the four other states, implying a lack of interaction between the plasma and accretion disk. The system evolves between these two extreme states, with the spectral slope regulated by a variable cooling of the plasma by the disk photons., 21 pages, 11 figures, accepted for publication in ApJ

The relation between heliogeophysical factors and the osmotic pressure of blood plasma in patients with arterial hypertension with different temperaments is analyzed. It is found that with increasing solar activity (Wolf numbers and radio flux wavelength 10,7 cm), is closely related increase in atmospheric pressure, air temperature and γ-background (within normal limits) in the workplace examinees. It was revealed that in choleric and sanguine patients there is a reliable high inverse correlation relationship between heliogeophysical, meteorological factors and total peripheral vascular resistance, while the phlegmatic and melancholic - the average direct and direct high correlation relationship. Antihypertensive therapy with diuretics with increased solar activity, combined with an increase in the atmospheric pressure, γ-background and the air temperature in the workplace, due a decrease in total peripheral vascular resistance at the choleric and sanguine and increase in total peripheral vascular resistance in healthy individuals and phlegmatic patients and melancholic. The presence of significant and reverse correlation relationship between the total peripheral vascular resistance and osmotic pressure of blood plasma in choleric and sanguine and significant, but a direct correlation - the phlegmatic and melancholic indicates the inclusion of an adaptive process various physiological mechanisms, which determines the need to consider the temperament at solar biospheric relations bonds.

In the present study we have cross-correlated NVSS and FIRST radio catalogues having radio flux measurements at the same 1.4 GHz frequency. This way we benefit from repeated observations from both catalogues, as they give more accurate positions and fluxes and more important, reveal large differences between the two measured fluxes, thus allowing to establish radio variability. As a result 79,382 radio variables have been revealed, including 6301 with flux differences at 1.4 GHz larger than 15 mJy, 1917 with flux differences > 45 mJy and 260 with flux differences > 200 mJy. By using a special technique (Mickaelian & Sinamyan 2010, Mickaelian et al. 2011), 2425 optically variable objects out of 6301 radio sources have been revealed. 2425 radio sources with both high radio and optical variability into four categories have been divided. 1206 (19%) out of 6301 radio sources have activity types from available catalogues and 619 (25.5%) out of 2425 radio sources with at the same time radio and optical variability have activity types from available catalogues. In addition, 279 radio sources out of 2425 have high variability in optical range. We have established their activity types when available. The IR fluxes and colours for the 6301 variable radio sources have been studied. Colour–colour diagrams show that most of the “unknown” sources are galaxies. The activity types for 110 (42%) out of 260 extremely high variable radio sources also have been retrieved.

Low-degree solar p-mode observations from the long-lived Birmingham Solar Oscillations Network (BiSON) stretch back further than any other single helioseismic data set. Results from BiSON have suggested that the response of the mode frequency to solar activity levels may be different in different cycles. In order to check whether such changes can also be seen at higher degrees, we compare the response of medium-degree solar p-modes to activity levels across three solar cycles using data from Big Bear Solar Observatory (BBSO), Global Oscillation Network Group (GONG), Michelson Doppler Imager (MDI) and Helioseismic and Magnetic Imager (HMI), by examining the shifts in the mode frequencies and their sensitivity to solar activity levels. We compare these shifts and sensitivities with those from radial modes from BiSON. We find that the medium-degree data show small but significant systematic differences between the cycles, with solar cycle 24 showing a frequency shift about 10 per cent larger than cycle 23 for the same change in activity as determined by the 10.7 cm radio flux. This may support the idea that there have been changes in the magnetic properties of the shallow subsurface layers of the Sun that have the strongest influence on the frequency shifts., 6 pages, 3 figures, accepted by MNRAS 3rd July 2018

A reevaluation of the solar constant is undertaken here to take into account the progress in space radiometry that has occurred since the early 2000s. Various sources of spaceborne total solar irradiance (TSI) observations are investigated here, including the long-term ACRIM and PMOD composites, as well as recent observations from the SORCE-TIM, TCTE-TIM, and PICARD-PREMOS instruments. A proxy model is constructed using daily data of sunspot number, radio flux at 10.7 cm, and MgII index, as predictors for TSI over the 42-year period 1976–2017. These daily estimates are used to fill in 9.7% of missing TSI observations during that period. By comparison with these proxy estimates, the PMOD composite appears generally more reliable than the ACRIM composite before 2003, and particularly before 1981. The 42-year time span is separated into nine periods, each defining the revised TSI daily values from one or more sources that are selected based on the trend of their resemblance with the proxy model. A final correction is added to emulate the highly accurate absolute calibration of PREMOS. Based on the resulting TSI reconstruction, a revised solar constant value of 1361.1 W/m2 is obtained, with a standard uncertainty of 0.5 W/m2. The revised solar constant is ≈5 W/m2 less than the previous values promulgated in ASTM and ISO standards. A revision of these standards is thus highly recommended.

The radio spectrum of Tycho’s Supernova Remnant is constructed at frequencies 12.6–143 000 MHz for epoch 2010.3, taking into account the secular decrease in the radio flux density of the remnant at the rate d = −(0.46 ± 0.03)%/year: $$S_\nu ^{3C10} (t = 2010.3) = (43.1 \pm 1.8 Jy)(\nu [GHz])^{ - (0.592 \pm 0.019) + (0.041 \pm 0.012)\log (\nu [GHz])} .$$ The spectrum has positive curvature. The presence of a low-frequency turnover in the spectrum of the radio source 3C10 with its maximum at 7.7 MHz is predicted, due to absorption in the interstellar medium in the direction toward the source.

Using 3 years (2013–2015) of O2(0–1) and OH(6–2) band nightglow emission intensities and corresponding rotational temperatures as tracers of mesospheric dynamics, we have investigated large- and small-timescale variations in the mesosphere over a low-latitude location, Gurushikhar, Mount Abu (24.6° N, 72.8° E), in India. Both O2 and OH intensities show variations similar to those of the number of sunspots and F10.7 cm radio flux with coherent periodicities of 150 ± 2.1, 195 ± 3.6, 270 ± 6.4, and 420 ± 14.8 days, indicating a strong solar influence on mesospheric dynamics. In addition, both mesospheric airglow intensities also showed periodicities of 84 ± 0.6, 95 ± 0.9, and 122 ± 1.3 days which are of atmospheric origin. With regard to the variability of the order of a few days, O2 and OH intensities were found to be correlated, in general, except when altitude-dependent atmospheric processes were operative. To understand mesospheric gravity wave behavior over the long term, we have carried out a statistical study using the periodicities derived from the nocturnal variations in all four parameters (O2 and OH intensities and their respective temperatures). It was found that the major wave periodicity of around 2 h duration is present in all the four parameters. Our analyses also reveal that the range of periods in O2 and OH intensities and temperatures is 11 to 24 and 20 to 60 min, respectively. Periods less than 15 min were not present in the temperatures but were prevalent in both emission intensities. No seasonal dependence was found in either the wave periodicities or the number of their occurrence.

We report observations of a transient source \fermi\ from radio to \grs. \fermi\ was discovered by the {\it Fermi-LAT} in May 2017. Follow-up {\it Swift-XRT} observations revealed three flaring episodes through March 2018, and the peak X-ray flux is about $10^3$ higher than the {\it ROSAT all-sky survey (RASS)} flux upper limit. Optical spectral measurements taken by the {\it Magellan 6.5-m telescope} and the {\it Lick-Shane telescope} both show a largely featureless spectrum, strengthening the BL Lac interpretation first proposed by \citet{Bruni18}. The optical and mid-infrared (MIR) emission goes to a higher state in 2018, when the flux in high energies goes down to a lower level. Our {\it RATAN-600m} measurements at 4.8~GHz and 8.2~GHz do not indicate any significant radio flux variation over the monitoring seasons in 2017 and 2018, nor deviate from the archival {\it NVSS} flux level. During GeV flaring times, the spectrum is very hard ($\Gamma_\gamma\sim$1.7) in the GeV band and at times also very hard (($\Gamma_{\rm X}\lesssim2$) in the X-rays, similar to a high-synchrotron-peak (or even an extreme) BL Lac object, making \fermi\ a good target for ground-based {\it Cherenkov telescopes}., Comment: Submitted in Journal of High Energy Astrophysics

In this work, a nearby luminous AGN sample is selected from HST, where only sources with both X-ray emission observed by \textit{Chandra/XMM-Newton} and radio flux detected by VLA/VLBA/VLBI/MERLIN are adopted to keep high precision. We get a sample of 30 luminous AGNs finally, which consist of 11 RLAGN and 19 RQAGN. It is found that the relationship between $R_{\rm {UV}}$ and $\alpha_{\rm {ox}}$, which was firstly reported by Li & Xie (2017) in LLAGN, and other relationships are all absent in RLAGN, probably due to the complex physical process therein. Our results indicate that the X-ray emission from jet should play an important role in RLAGN and further support the transition of accretion mode between LLAGN and RLAGN. On the other hand, the traditional relationships in RQAGN, such as $\alpha_{\rm {ox}}$ and $\lambda$, $\Gamma$ and $\lambda$, are found to be well consistent with previous works., Comment: 6 pages, 2 figures, accepted by MNRAS

Recent radio surveys have discovered a large number of low luminosity core dominated radio galaxies that are much more abundant than those at higher luminosities. These objects will be too faint in gamma-rays to be detected individually by Fermi. Nevertheless, they may contribute significantly to the unresolved extragalactic gamma-ray background. We consider here the possible contribution of these core dominated radio galaxies to the diffuse extragalactic gamma-ray background. Using published data available for all 45 of the radiogalaxies listed as detected counterparts in the Fermi FL8Y source list update to the 3FGL catalog, we have searched for radio maps which can resolve the core flux from the total source flux. Using high resolution radio maps we were able to obtain core fluxes for virtually every source. We then derived a relation between core radio flux and gamma-ray flux that we extrapolated to sources with low radio luminosities that are known to be highly core dominated. We then employed a very recent determination of the luminosity function for core dominated radio galaxies in order to obtain the contribution of all possible gamma-ray emitting radio galaxies to the unresolved extragalactic gamma-ray background. We find this contribution to be a possibly non-negligible, 4% - 18% of the background., Comment: 7 pages, 5 figures, Accepted for publication in the Astrophysical Journal

We use the new release of the AKARI Far-Infrared all sky Survey matched with the NVSS radio database to investigate the local ($z, 9 pages, accepted to PASJ

A correlation between solar activity and normalized occurrence rate of sudden stratospheric warmings (SSWs) has been found. As a proxy for solar activity, F10.7 cm radio flux has been used. In order to find the correlation, we derived a normalized occurrence rate of MSSWs based on both ERA40/ERA-Interim dataset and NCEP data. Based on this distribution, we calculated the correlation coefficient, which amounts to 0.6314, with a significance of 90.68 % for ERA40/ERA-Interim, and 0.5455 for NCEP-NCAR-I, with a significance of 83.80 %. Additionally, we calculate correlation coefficients for Lyman-alpha flux and sunspot numbers with the analogous method for the same period.

Radio emission from stars can be used, e.g., to study ionized winds or stellar flares. The radio emission is faint and studies have been limited to few objects. The Square Kilometer Array (SKA) will bring a survey ability to the topic of radio stars. In this paper we investigate what the SKA can detect, and what sensitivity will be required for deep surveys of the stellar Milky Way. We focus on the radio emission from OB stars, Be stars, flares from M dwarfs, and Ultra Compact HII regions. The stellar distribution in the Milky Way is simulated using the Besancon model, and various relations are used to predict their radio flux. We find that the full SKA will easily detect all UltraCompact HII regions. At the limit of 10 nJy at 5 GHz, the SKA can detect 1500 Be stars and 50 OB stars per square degree, out to several kpc. It can also detect flares from 4500 M dwarfs per square degree. At 100 nJy the numbers become about 8 times smaller. SKA surveys of the Galactic plane should be designed for high sensitivity. Deep imaging should consider the significant number of faint flares in the field, even outside the plane of the Milky Way., 23 pages, 13 figures

We report on radio and X-ray monitoring observations of the BHC Swift J1753.5-0127 taken over a ~10 year period. Presented are daily radio observations at 15 GHz with the AMI-LA and X-ray data from Swift XRT and BAT. Also presented is a deep 2hr JVLA observation taken in an unusually low-luminosity soft-state (with a low disk temperature). We show that although the source has remained relatively radio-quiet compared to XRBs with a similar X-ray luminosity in the hard-state, the power-law relationship scales as $\zeta=0.96\pm0.06$ i.e. slightly closer to what has been considered for radiatively inefficient accretion disks. We also place the most stringent limit to date on the radio-jet quenching in an XRB soft-state, showing the connection of the jet quenching to the X-ray power-law component; the radio flux in the soft-state was found to be $, Comment: 8 pages, 4 figures, Accepted for publication in MNRAS