We present the X-ray analysis of a deep ~200 ksec Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z=1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution (SED), adopting several scenarios for the jet emission. For the values of the main physical parameters favored by the observables, a dominant role of the jet emission in the X-ray band is ruled out when a single zone (leptonic) scenario is adopted, even including the contribution of the external photon fields as seed photons for inverse Compton emission. We then consider a structured jet, with the blazar component that- although not directly visible in the X-ray band - provides an intense field of seed synchrotron photons Compton-scattered by electrons in a mildly relativistic knot. In this case the whole X-ray emission can be accounted for if we assume a blazar luminosity within the range observed from flat spectrum radio quasars. The X-ray radiative efficiency of such (structured) jet is intimately related to the presence of a complex velocity structure. The jet emission can provide a significant contribution in X-rays if it decelerates within the host galaxy, on kiloparsec scales. We discuss the implications of this model in terms of jet dynamics and interaction with the ambient medium.
PKS 0202$+$149 is a low-power radio source with blazar-like $γ$-ray AGN characteristics and its properties and classification are investigated in relation to its $γ$-ray characteristics. It shows a hint of low frequency turnover at about 200 MHz. Radio imaging data of 0202$+$149 at different frequencies show differing morphologies on both kilo-parsec (kpc) and parsec (pc) scales. The overall source shows a triple structure of core and double lobes with a total projected size of $\sim$1.3 kpc. The compact source structure of 0202+149 is reminiscent of a compact steep spectrum (CSS) source. At p…
In the manuscript, a 3.8yr optical quasi-periodic oscillations (QPOs) is reported in blue quasar SDSS J132144+033055 (=\obj) at $z=0.269$, based on 16.3yr-long light curve from both CSS and ZTF directly described by a sinusoidal function. The 3.8yr QPOs can be confirmed through the Generalized Lomb-Scargle periodogram with confidence level higher than 5$σ$, through properties of the phase-folded light curve and the WWZ technique. Moreover, the collected Pan-STARRS light curves well follow the sinusoidal function described best fitting results to the CSS and ZTF light curves. The optical QPOs s…
Multifrequency radio continuum observations (1.4-22 GHz) of a sample of reddened QSOs are presented. We find a high incidence (13/16) of radio spectral properties, such as low frequency turnovers, high frequency spectral breaks or steep power-law slopes, similar to those observed in powerful compact steep spectrum (CSS) and gigahertz-peaked spectrum (GPS) sources. The radio data are consistent with relatively young radio jets with synchotron ages <1e6-1e7yr. This calculation is limited by the lack of high resolution (milli-arcsec) radio observations. For the one source in the sample that such …
Unexpected Gamma-ray Outburst from the CSS Radio Galaxy 3C 216
Istituto Nazionale di Fisica Nucleare, INFN, Roma Tor Vergata（意大利国家核物理研究所，罗马托尔维加塔分部）；Space Science Data Center, SSDC, Agenzia Spaziale Italiana, ASI（意大利航天局空间科学数据中心）；Department of Fundamental Physics, University of Salamanca（萨拉曼卡大学基础物理系）
We present a comprehensive analysis of Chandra X-ray observations of 15 young radio quasars at redshifts $4.5 < z < 5.0$. All sources are detected in the $0.5-7.0$ keV energy band. Emission spectra are extracted, and the average photon index for the sample is measured to be $1.5\pm0.1$. Unabsorbed rest-frame $2-10$ keV luminosities are found to range between $(0.5-23.2) \times 10^{45}$ erg s$^{-1}$. The optical-X-ray power-law spectral index $α_{ox}$ is calculated for each source using optical/UV data available in the literature. The $α_{ox}$-UV relationship is compared with other quasar surve…
The BH masses and the Eddington ratios for a sample of 65 young radio galaxies [27 GPS and 38 CSS sources] are estimated by various methods. We find that the average BH mass of these young radio galaxies is <log M_bh>=8.3, which is less than that of radio loud QSOs and low redshift radio galaxies(<log M_bh>=9.0). The CSS/GPS sources have relatively high Eddington ratios with average ratio <log L_bol/L_Edd>=-0.56, which are similar to those of narrow line Seyfert 1 galaxies (NLS1s). It suggests that the CSS/GPS sources may not only be in the early stage of radio activities, but also in the earl…
We discovered an X-ray cluster in a recent pointed Chandra observation of the radio-loud compact-steep-spectrum source 1321+045 at the redshift of 0.263. 1321+045 is part of larger survey which aims to study the X-rays properties of weak compact radio sources. Compact radio sources are young objects at the beginning of their evolution and if embedded in an X-ray cluster offer unique opportunities to study the cluster heating process.
According to radiative models, radio galaxies and quasars are predicted to produce gamma rays from the earliest stages of their evolution. Exploring their high-energy emission is crucial for providing information on the most energetic processes, the origin and the structure of the newly born radio jets. Taking advantage of more than 11 years of \textit{Fermi}-LAT data, we investigate the gamma-ray emission of 162 young radio sources (103 galaxies and 59 quasars), the largest sample of young radio sources used so far for such a gamma-ray study. We separately analyze each source and perform the …
Compact steep-spectrum sources (CSSs) likely represent a population of young radio-loud active galactic nuclei (AGNs) and have been identified as gamma-ray emitting sources. We present a comprehensive analysis of their gamma-ray emission observed with Fermi/LAT and establish their broadband spectral energy distributions (SEDs). We derive their jet properties by the SED fits with a two-zone leptonic model for radiations from the compact core and large-scale extended region, and explore the possible signature of a unification picture of jet radiation among subclasses of AGNs. We show that the ob…
According to radiative models, radio galaxies are predicted to produce gamma-rays from the earliest stages of their evolution onwards. The study of the high-energy emission from young radio sources is crucial for providing information on the most energetic processes associated with these sources, the actual region responsible for this emission, as well as the structure of the newly born radio jets. Despite systematic searches for young radio sources at gamma-ray energies, only a handful of detections have been reported so far. Taking advantage of more than 11 years of Fermi-LAT data, we invest…
According to radiative models, radio galaxies are predicted to produce gamma rays from the earliest stages of their evolution onwards.The study of the high-energy emission from young radio sources is crucial for providing information on the most energetic processes associated with these sources, the actual region responsible for this emission, as well as the structure of the newly born radio jets. Despite systematic searches for young radio sources at gamma-ray energies, only a handful of detections have been reported so far. Taking advantage of more than 11 years of \textit{Fermi}-LAT data, w…
We report first X-ray Chandra observations of a sample of seven low luminosity compact (LLC) sources. They belong to a class of young compact steep spectrum (CSS) radio sources. Four of them have been detected, the other three have upper limit estimations for X-ray flux, one CSS galaxy is associated with an X-ray cluster. We have used the new observations together with the observational data for known strong CSS and gigahertz-peaked spectrum (GPS) objects and large scale FRIs and FRIIs to study the relation between morphology, X-ray properties and excitation modes in radio-loud AGNs. We found …
We estimate black hole masses and Eddington ratios for a sample of 81 young radio galaxies (42 CSS +39 GPS). We find that the average black hole (BH) mass of these young radio galaxies is <log Mbh>~8.3, which is less than that of radio loud QSOs and low redshift radio galaxies. The CSS/GPS sources have relatively high Eddington ratios, with an average value of <log Lbol/LEdd>=-0.75, which are similar to those of narrow line Seyfert 1 galaxies (NLS1s). This suggests that young radio galaxies may not only be in the early stages of their radio activity, but also in the early stage of their accret…
In this work, we investigated the X-ray emission for a sample of young radio AGNs by combining their data from Chandra/XMM-Newton and at other wavebands. We find strong correlations between the X-ray luminosity $L_{\rm X}$ in 2$-$10 keV and the radio luminosities $L_{\rm R}$ at 5 GHz for VLBI radio-core, VLA radio-core and FIRST component, indicating that both pc- and kpc-scale radio emission strongly correlate with X-ray emission in these sources. We find approximately linear dependence of radio on X-ray luminosity in the sources with radiative efficient accretion flows (i.e., the Eddington r…
We present new results on X-ray properties of radio loud broad absorption line (BAL) quasars and focus on broad-band spectral properties of a high ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We applied theoretical models to explain spectral energy distribution (SED) of 1045+352 and argue that …
We started a follow-up investigation of the Deep X-ray Radio Blazar Survey objects with declination >-10 deg. We undertook a survey with the EVN at 5GHz to make the first images of a complete sample of weak blazars, aiming at a comparison between high- and low-power samples of blazars. All of the 87 sources observed were detected. Point-like sources are found in 39 cases, and 48 show core-jet structure. According to the spectral indices previously obtained, 58 sources show a flat spectral index, and 29 sources show a steep spectrum or a spectrum peaking at a frequency around 1-2 GHz. Adding to…
We conducted the first multi-frequency polarimetric imaging of four broad absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond resolutions to investigate the inclination of the non-thermal jet and test the hypothesis that radio sources in BAL quasars are still young. Among these four sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in parsec scales, and polarized emission detected in the core. These characteristics are consistent with those of blazars. We set constraints on viewing angles to $<$66 deg for these jets, in the framework of a Dopp…
This paper reports very-long-baseline interferometry observations of the radio-loud broad absorption line (BAL) quasar J1020+4320 at 1.7, 2.3, 6.7, and 8.4 GHz using the Japanese VLBI network (JVN) and European VLBI network (EVN). The radio morphology is compact with a size of ~10 pc. The convex radio spectrum is stable over the last decade; an observed peak frequency of 3.2 GHz is equivalent to 9.5 GHz in the rest frame, suggesting an age of the order of ~100 years as a radio source, according to an observed correlation between linear size and peak frequency of compact steep spectrum (CSS) an…
Thirteen yr observation data of 4FGL J0824.9+3915 with the Large Area Telescope on board the Fermi Gamma Ray Space Telescope (Fermi/LAT) are analyzed for revisiting whether 4C +39.23B, a compact steep-spectrum (CSS) source closed to a flat-spectrum radio quasar (FSRQ) 4C +39.23A in the $γ$-ray emitting region of 4FGL J0824.9+3915, is a $γ$-ray emitter. We find that the time-integrated $γ$-ray emission of 4FGL J0824.9+3915 is overwhelmingly dominated by 4C +39.23A. It shows significant variability at a 6.7$σ$ confidence level and the average $γ$-ray flux in the 0.1--300 GeV energy band is $(1.6…
We present the discovery of PSO J191.05696$+$86.43172 (hereafter PSO J191$+$86), a new powerful radio-loud quasar (QSO) in the early Universe (z = 5.32). We discovered it by cross-matching the NRAO VLA Sky Survey (NVSS) radio catalog at 1.4 GHz with the first data release of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS PS1) in the optical. With a NVSS flux density of 74.2 mJy, PSO J191$+$86 is one of the brightest radio QSO discovered at z$\sim$5. The intensity of its radio emission is also confirmed by the very high value of radio loudness (R>300). The observed radio s…
There are approximately 250 quasars discovered at redshift $z\geq6$, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we report the results of our dual-frequency observations with the Very Long Baseline Array (VLBA) of two such recently discovered quasars, VIKING J231818.35$-$311346.3 at $z=6.44$ and FIRST J233153.20$+$112952.11 at $z=6.57$. Both extremely distant sources were imaged with VLBI for the first time. The radio properties of the former are consistent with those of qu…
New results on the radio-quiet type 2 quasar known as the Teacup galaxy (SDSSJ1430+1339) based on the long-slit and 3D spectroscopic data obtained at the Russian 6-m telescope are presented. The ionized gas giant nebula extending up to r=56 kpc in the [O III] emission line was mapped with the scanning Fabry-Perot interferometer. The direct estimation of the emission line ratios confirmed that the giant nebula is ionized by the AGN. Stars in the inner r<5 kpc are significantly younger than the outer host galaxy and have a solar metallicity. The central starburst age (~1 Gyr) agrees with possibl…
We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network (JVN). We aimed at selecting BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversi…
