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Gamma-Ray Emission from the Broad-Line Radio Galaxy 3C 111

The broad-line radio galaxy 3C 111 has been suggested as the counterpart of the y-ray source 3EG J0416+3650. While 3C 111 meets most of the criteria for a high-probability identification, like a bright flat-spectrum radio core and a blazar-like broadband SED, in the Third EGRET Catalog, the large positional offset of about 1.5' put 3C 111 outside the 99% probability region for 3EG J0416+3650, making this association questionable. We present a re-analysis of all available archival data for 3C 111 from the EGRET archives, resulting in detection of variable hard-spectrum high-energy gamma-ray emission above 1000 MeV from a position close to the nominal position of 3C 111, in three separate viewing periods (VPs), at a 3sigma level in each. A second variable hard-spectrum source is present nearby. At >100 MeV, one variable soft-spectrum source seems to account for most of the EGRET-detected emission of 3EG J0416+3650. A follow-up Swift UVOT/XRT observation reveals one moderately bright X-ray source in the error box of 3EG J0416+3650, but because of the large EGRET position uncertainty, it is not certain that the X-ray and gamma-ray sources are associated. Another Swift observation near the second (unidentified) hard gamma-ray source detected no X-ray source nearby.

Hartman, Robert C.↗

Suzaku View of the Swift/BAT Active Galactic Nuclei. V. Torus Structure of Two Luminous Radio-Loud Active Galactic Nuclei (3C 206 and PKS 0707-35)

We present the results from broadband X-ray spectral analysis of 3C 206 and PKS 0707−35 with Suzaku and Swift/BAT, two of the most luminous unobscured and obscured radio-loud active galactic nuclei (AGNs) with hard X-ray luminosities of 10(sup 45.5) erg per second and 10(sup 44.9) erg per second (14-195 keV), respectively. Based on the radio core luminosity, we estimate that the X-ray spectrum of 3C 206 contains a significant (∼60% in the 14-195 keV band) contribution from the jet, while it is negligible in PKS 0707−35.We can successfully model the spectra with the jet component (for 3C 206), the transmitted emission, and two reflection components from the torus and the accretion disk. The reflection strengths from the torus are found to be R(sub torus)(≡Omega/2pi) = 0.29 +/- 0.18 and 0.41 +/- 0.18 for 3C 206 and PKS 0707−35, respectively, which are smaller than those in typical Seyfert galaxies. Utilizing the torus model by Ikeda et al., we quantify the relation between the half-opening angle of a torus (theta(sub oa)) and the equivalent width of an iron-K line. The observed equivalent width of 3C 206, less than 71 eV, constrains the column density in the equatorial plane to N(sup eq)(sub H) lesst han 10(sup 23) per square centimeter, or the half-opening angle to theta(sub oa) greater than 80 deg. if N(sup eq)(sub H) = 10(sup 24) per square centimeter is assumed. That of PKS 0707−35, 72 +/- 36 eV, is consistent with N(sup eq)(sub H) ∼ 10(sup 23) per square centimeter. Our results suggest that the tori in luminous radio-loud AGNs are only poorly developed. The trend is similar to that seen in radio-quiet AGNs, implying that the torus structure is not different between AGNs with jets and without jets.

Suzaku↗

Measurements of Breakdown Field and Forward Current Stability in 3C-SiC P-N Junction Diodes Grown on Step-Free 4H-SiC

This paper reports on initial fabrication and electrical characterization of 3C-SiC p-n junction diodes grown on step-free 4H-SiC mesas. Diodes with n-blocking-layer doping ranging from approx. 2 x 10(exp 16)/cu cm to approx.. 5 x 10(exp 17)/cu cm were fabricated and tested. No optimization of junction edge termination or ohmic contacts was employed. Room temperature reverse characteristics of the best devices show excellent low-leakage behavior, below previous 3C-SiC devices produced by other growth techniques, until the onset of a sharp breakdown knee. The resulting estimated breakdown field of 3C-SiC is at least twice the breakdown field of silicon, but is only around half the breakdown field of <0001> 4H-SiC for the doping range studied. Initial high current stressing of 3C diodes at 100 A/sq cm for more than 20 hours resulted in less than 50 mV change in approx. 3 V forward voltage. 3C-SiC, pn junction, p+n diode, rectifier, reverse breakdown, breakdown field,heteroepitaxy, epitaxial growth, electroluminescence, mesa, bipolar diode

Neudeck, Philip G.↗

Broadband multiwavelength properties of the archetypal blazar 3C 279 during the 2017 Event Horizon Telescope campaign

The archetypal blazar 3C 279 hosts a prominent relativistic jet and exhibits strong broadband variability across the electromagnetic spectrum. In April 2017, the Event Horizon Telescope (EHT) observed 3C 279, alongside one of the most extensive quasi-simultaneous multiwavelength (MWL) campaigns ever conducted. With the aim of investigating the physical processes governing 3C 279, we analyzed individual observations and multiband light curves, and constructed a new quasi-simultaneous MWL spectrum. We also performed phenomenological modeling using the turbulent extreme multi-zone (TEMZ) model to constrain the fundamental physical properties of the source. The EHT observations reveal a clear flux increase in the innermost core between April 5 and 11, 2017. Over a broader timescale, radio measurements at longer wavelengths show concurrent enhancements in core flux and polarization around mid-April, coinciding with the ejection of a superluminal knot. Record UV-optical flares with strong polarization variability occurred in late March, followed by gamma-ray activity that declined before the end of the EHT observing period. During this interval, the source remained in a low X-ray state and showed no detectable VHE emission. The TEMZ modeling suggests that the broadband spectrum and variability of 3C 279 can be explained within a jet scenario in which turbulent plasma cells are compressed by a stationary conical shock. However, alternative interpretations, such as magnetic reconnection or a moving shock-in-jet event, remain plausible. This coordinated MWL campaign advances our understanding of the origin of jet and gamma-ray emission in 3C 279, while also providing a comprehensive publicly available dataset that will serve as a valuable reference for future studies.

Principe, G. [Trieste U.; INFN, Trieste; Bologna, ↗

Numerical simulations of colliding jets in an external wind: application to 3C 75

ABSTRACT The radio galaxy 3C 75 is remarkable because it contains a pair of radio-loud active galaxies, each of which produces a two-sided jet, with the jet beams appearing to collide and merge to the west of the galaxies. Motivated by 3C 75, we have conducted three-dimensional hydrodynamic simulations of jet collisions. We have extended previous studies by modelling the physical properties of the cluster atmosphere, including an external wind, and using realistic jet powers obtained from observational data. We are able to produce a morphology similar to that of 3C 75. The simulations imply that direct contact between the bulk jet flows on the west of the source is required to produce a morphology consistent with 3C 75. We quantify how the merging jets decelerate, how the wind deflects the jets and cocoons, the entrainment of intra-cluster material into the cocoons, the cocoon energetics, and how the jet interactions generate enstrophy. By comparing simulations of pairs of two-sided jets with those of single two-sided sources, we determine how the interaction between two bipolar jets changes their evolution. The unprecedented sensitivity and angular resolution of upcoming observatories will lead to the detection of many more complex sources at high redshift, where interacting jets are expected to be more numerous. The morphology of these complex sources can provide significant insight into the conditions in their environments.

Musoke, G.↗

Spectroscopic classification, variability, and SED of the Fermi -detected CSS 3C 286: the radio-loudest NLS1 galaxy?

ABSTRACT 3C 286 is a well-known calibrator source in radio astronomy. It is also one of very few compact steep-spectrum (CSS) sources detected in γ-rays. Here, we perform a detailed spectroscopic and variability analysis and present the first quasi-simultaneous optical to X-ray spectral energy distribution (SED) in order to reveal physical mechanisms that dominate its emission at different wavelengths, and arrive at a reliable optical source classification. The first main result of our study reveals several pitfalls when applying simple broad- or narrow-line Seyfert 1 (BLS1 or NLS1) classification criteria that only look at the [O iii]–Hβ complex. [O iii] and Hβ can be dominated by the same outflow components, in which case full width at half-maximum (Hβ) is no reliable classification criterion, and extinction by intrinsic or intervening material can make the highest velocity Hβ component undetectable. After careful combination of all information from ultraviolet (UV)–optical spectra along with multiwavelength data, we confirm that 3C 286 can be classified as NLS1 galaxy, with line properties and supermassive black hole mass (of order 108 M⊙ and accreting near the Eddington limit) close to the BLS1 regime, making it an important borderline object. The quasi-simultaneous SED taken with Swift shows a sharp rise in the optical–UV, implying the presence of a strong accretion-disc component with extreme UV excess, consistent with emission-line diagnostics. Finally, we report the discovery of X-ray variability of 3C 286, plausibly dominated by jet emission, and variable by at least a factor of ∼4. This result suggests to exercise caution when using 3C 286 as radio calibrator in high-resolution radio very long baseline interferometry observations.

Yao, Su↗

VLBI observations of 3C 345 and NRAO 512 in right and left circular polarization

In October 1975, the radio telescopes of the Haystack, National Radio Astronomy, and Owens Valley Radio Observatories were used as an interferometer to monitor, at 8 GHz, the right and left circularly polarized radiation emitted by the quasars 3C 345 and NRAO 512. The data for each polarization are used separately to estimate several parameters describing a model of the fine structure of the radio brightness of 3C 345 and, subsequently, the angular separation between 3C 345 and NRAO 512. The results for the two polarizations are in approximate agreement, indicating that to the limit of resolution about 0.5 milliarcsec), the fourth Stokes parameter, V, is not significantly different from zero within the compact components of these radio sources. The corresponding quantitative limits on the degree of circular polarization are 0.08 + or - 0.07 for 3C 345 and 0.01 + or - 0.08 for NRAO 512.

Menyuk, C. R.↗

Constraints on continuous beam models of the jet in 3C 273

The one-sidedness, 'superluminal' motion, and detailed spectra observed for 3C 273 put significant constraints on continuous beam models for the source of the extended emission in 3C 273 A. The one-sidedness of the extended emission implies that the age of the radio-frequency cloud is probably about 3-5 Myr. The 'superluminal' motion observed with VLBI constrains the bulk Lorentz factor of the jet to be more than about 10. Finally, the observed X-ray emission from the jet provides a method for deciding the question of beam composition: for a given beam power, an electron-positron beam would produce a much higher (beamed) inverse-Compton X-ray flux off extended-jet optical photons than an electron-proton beam would, thus making the observed weak jet X-ray flux a strong indicator of a proton positive component to the jet. Remaining experimental uncertainties in the case of 3C 273 make it impossible to decide the question of beam composition at present, but the next generation of experiments may make this possible for 3C 273 and other 'superluminal' objects. The above arguments have the advantage of not depending on the details of the mechanism for producing the high-energy radio-cloud electrons.

Roberts, D.↗

The nature of the optical variations of Seyfert galaxy 3C 120

Results are presented from 61 years of optical observations of the Seyfert galaxy 3C 120. A previously published model of the 3C 120 light curve, derived from power spectrum analysis, is found to be valid for historical as well as current data. It is concluded that the optical variations of 3C 120 can be separated into a linear component, a sinusoidal component, and rapid, high-amplitude flares. Possible sources of the regular variations observed in 3C 120 are also suggested in the context of accretion models and other theoretical models.

Webb, James R.↗

Probing the Interstellar Medium of External Galaxies Using Quasar Absorption Lines: the 3C 232/NGC 3067 System

Quasar absorption lines offer unique opportunities to probe the interstellar medium of external galaxies. Researchers present new optical and UV absorption line spectroscopy of the quasar 3C232 (z=0.55) revealing new detail in the foreground absorption system due to the bright, spiral galaxy NGC 3067 (cz=1420 km/s). Specifically, the spectra show evidence for two and possibly three separate absorption components in CaII and Na I spanning approx. 150 km/s. The original HI detection of Haschick and Burke (1975) corresponds to the strongest of these metal systems which exhibits doublet ratios consistent with saturation in both CaII and Na I. Due to the recent detection in HI emission of a tidal tail or finger of HI extending from the western edge of NGC 3067 through the position of 3C 232 (Carilli, van Gorkom and Stocke, 1989), the morphology of the HI absorber is now known and is not either a warped disk nor a spherical halo as had been proposed. New deep continuum and H alpha imaging provides a sensitive upper limit on the the ionizing continuum impinging upon this cloud (and thus a limit on the intensity of the extragalactic ionizing radiation field). Together with the observed UV spectrum of 3C 232, the optical emission line ratios and the deep H alpha imaging set a minimum distance between the quasar and the HI cloud disregarding redshift information. This limit strains the non-cosmological redshift interpretation for 3C 232 -- and this quasar is one of the original 5 3C quasars found to be too close to NGC galaxies as if by chance (Burbidge, Burbidge, Solomon and Strittmatter, 1972).

Stocke, John T.↗

Greatly improved 3C-SiC p-n junction diodes grown by chemical vapor deposition

This paper reports the fabrication and initial electrical characterization of greatly improved 3C-SiC (beta-SiC) p-n junction diodes. These diodes, which were grown on commercially available 6H-SiC substrates by chemical vapor deposition, demonstrate rectification to -200 V at room temperature, representing a fourfold improvement in reported 3C-SiC diode blocking voltage. The reverse leakage currents and saturation current densities measured on these diodes also show significant improvement compared to previously reported 3C-SiC p-n junction diodes. When placed under sufficient forward bias, the diodes emit significantly bright green-yellow light. These results should lead to substantial advancements in 3C-SiC transistor performance.

Neudeck, Philip G.↗

The linear polarization of 3C 345 in the ultraviolet

The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 A and 2770 A) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p greater than 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.

Dolan, Joseph F.↗

The Hyperluminous Infrared Quasar 3C 318 and Its Implications for Interpreting Sub-MM Detections of High-Redshift Radio Galaxies

We present near-infrared spectroscopy and imaging of the compact steep-spectrum radio source 3C 318 which shows it to be a quasar at redshift z = 1.574 (the z = 0.752 value previously reported is incorrect). 3C 318 is an IRAS, ISO and SCUBA source so its new redshift makes it the most intrinsically luminous far-infrared (FIR) source in the 3C catalogue (there is no evidence of strong gravitational lensing effects). Its bolometric luminosity greatly exceeds the 10(exp 13) solar luminosity level above which an object is said to be hyperluminous. Its spectral energy distribution (SED) requires that the quasar heats the dust responsible for the FIR flux, as is believed to be the case in other hyperluminous galaxies, and contributes (at the greater than 10% level) to the heating of the CIA dust responsible for the sub-mm emission. We cannot determine whether a starburst makes an important contribution to the heating of the coolest dust, so evidence for a high star-formation rate is circumstantial being based on the high dust, and hence gas, C-1 mass required by its sub-mm detection. We show that the current sub-mm and FIR data available for the highest-redshift radio galaxies are consistent with SEDs similar to that of 3C 318. This indicates that at least some of this population may be detected in the sub-mm because of dust heated by the quasar nucleus, and that interpreting sub-mm detection as evidence for very high (approx. less than 1000 solar mass/yr) star-formation rates may not always be valid. We show that the 3C318 quasar is slightly reddened (A(sub v) approx. = 0.5), the most likely cause of which is SMC-type dust in the host galaxy. If very distant radio galaxies are reddened in a similar way then we show that only slightly greater amounts of dust could obscure the quasars in these sources. We speculate that the low fraction of quasars amongst the very high redshift (z approx. greater than 3) objects in low-frequency radio-selected samples is the result of such obscuration. The highest-z objects might be preferentially obscured because like 3C318 they are inevitably observed very shortly after the jet-triggering event, or because their host galaxies are richer in dust and gas at earlier cosmic epochs, or because of some combination of these two effects.

Willott, Chris J.↗

Ballistic Models for Radio Jets in Colliding Galaxies: 3C 278 (NGC 4782/4783)

We present here a general numerical simulation algorithm for ballistic radio jets. The evolution of the jets is determined by their response to mechanical forces (i.e., gravity and ram pressure). Using a previously derived collision model for the interacting pair of elliptical galaxies NGC 4782/4783, we have used this algorithm to simulate the specific two-sided jet morphology seen in the radio source associated with NGC 4782 (3C 278). This is the first time such simulations have been attempted for a galaxy pair whose relative orbit was determined independently from the jet modeling. The general morphological features of the jets in 3C 278 (e.g., position angles, lengths, curvature, and deflection angles) are well matched by the simulations, indicating that our model of the mechanical forces acting on the jets can indeed reproduce most of the basic details of the jet morphology and thereby provide an opportunity to model a combination of detailed optical, radio, and X-ray data for a wide variety of interacting radio-jet galaxies. Our models constrain the initial jet parameters (i.e., the ejection speed, direction, and starting time), the properties of the gaseous medium into which the jets are ejected, and the relative importance of gravitational deflection versus ram pressure bending in influencing the jet morphology. For 3C 278, we find that the effects of ram pressure dominate the structural evolution of the jets. In our best-fit simulation the jet ejection speed is of order 10(exp 4) km/s, to within 50%, suggesting that similar low-luminosity radio jets are also significantly subluminal. We also find that the jets are ejected within approximately 5 deg of the line of sight, the ISM in the nonjet galaxy has a much larger effect on the jet deflection than does the host galaxy, and the jet activity began just over 70 million years ago, roughly 50 million years before the pericenter passage of the two galaxies. Therefore, the onset of nuclear activity appears in 3C 278 to be related to the kinematically observed tidal shock that has been induced in the core of NGC 4782 as a result of its deeply penetrating collision with NGC 4783.

Borne, Kirk D.↗

Growth of Defect-Free 3C-Sic on 4H- and 6H-SIC Mesas Using Step-Free Surface Heteroepitaxy

A new growth process, herein named step-free surface heteroepitaxy, has achieved 3C-SiC films completely free of double positioning boundaries and stacking faults on 4H-SiC and 6H-SiC substrate mesas. The process is based upon the initial 2-dimensional nucleation and lateral expansion of a single island of 3C-SiC on a 4H- or 6H-SiC mesa surface that is completely free of bilayer surface steps. Our experimental results indicate that substrate-epilayer in-plane lattice mismatch (Delta/a = 0.0854% for 3C/4H) is at least partially relieved parallel to the interface in the initial bilayers of the heterofilm, producing an at least partially relaxed 3C-SiC film without dislocations that undesirably thread through the thickness of the epilayer. This result should enable realization of improved 3C-SiC devices.

Neudeck, Philip G.↗

The Physics of AGN, a Deep Understanding of the Quasar 3C 273

Upon our successful AO-1 proposal no. 120023, the quasar 3C 273 has been observed with INTEGRAL in 3 epochs in January 2003. The first observation, on January 5, 2003, with a total INTEGRAL exposure of 1.2 x 10(exp 5) s, was simultaneous with RXTE and XMM- Newton observations. Two more INTEGRAL observations were carried out on January 11, 2003 (exposure: lo4 s) and January 17, 2003 (exposure: 1.1 x 10(exp 5) s). The source was detected with high significance by all INTEGRAL instruments, the OMC, JEM-X, SPI, and IBIS/ISGRI. Being one of the first INTEGRAL observations simultaneous with XMM and RXTE, our observations were also used to fix the cross calibration with those instruments. The combined spectrum resulting from the XMM-Newton, JEM-X, RXTE, SPI and ISGRI X-ray / soft gamma-ray observations is consistent with a straight power-law of photon index Gamma = (1.73 +/- 0.015) between 3 keV and at least 200 keV. A possible detection in the 200 keV - 500 keV band by SPI can not be confirmed with our observations. The normalization of the X/gamma-ray spectrum is (2.24 +/- 0.05) x 10(exp -2) photons /sq cm keV at 1 keV. The source showed a moderate amount of optical variability as observed with the OMC onboard INTEGRAL. No evidence for variability at X-rays and gamma-rays could be reported, which may have been a result of insufficient photon statistics. The X-/gamma-ray spectrum observed in our 2003 observations is consistent with previously measured and modelled broadband spectral energy distributions of 3C 273. It has been included in the U.S. lead Col's work on spectral and variability modelling of gamma-ray blazars, supporting the trend of flat-spectrum radio quasars such as 3C 273 being 7-ray dominated due to a strong contribution from Compton upscattering of external radiation by ultrarelativistic electrons in a relativistic jet. 3C 273 is a particularly convincing example for such a picture since it provides very direct evidence for a strong external radiation field by virtue of its obvious big blue bump, most likely originating in a very luminous accretion disk.

Courvoisier, T.↗

Jet-Intracluster Medium Interactions of the Head Tail Radio Galaxy 3C 129

The 50 ksec XMM observations of the galaxy cluster 3C 129 were taken as scheduled, and the data are of good quality. We analyzed the data in the following way. After standard cleaning, we flat-fielded the XMM surface brightness maps. Combining the data from the EPIC MOS and PN Camera CCDs, we performed a cross-correlation analysis of the X-ray surface brightness distribution with the 1.4 GHz VLA radio map. We found evidence for cavities in the X-ray emitting Intra-Cluster Medium (ICM) associated with the radio tail of the head-tail radio galaxy 3C 129. This discovery is very interesting as it excludes the presence of a large fraction of thermal plasma in the radio tail. Together with the observation of an apparent pressure mismatch between the radio plasma and the ICM, and an upper limit on the magnetic field inside the radio tail (from the radio spectral indices map) the observation implies that the tail pressure is dominated either by low-energy electrons/positrons, or, by relativistic protons. Furthermore, we studied the energy spectrum of an X-ray "hot-spot" associated with the head of the radio galaxy 3C 129. It seems likely that the X-ray hot-spot originates from shocked gas in front of the radio galaxy. , The analysis turned out to be much more difficult than anticipated. The main reason is the lack of a comprehensive, publicly available background model that is key for the analysis of extended sources. Small groups like our do not have the man-power to come up with a background model themselves. We used the model from Read & Ponman (A&A 409, 395, 2003). However, the background subtracted X-ray surface brightness maps show a bright ring in the outer 20% of the camera. We tried to get rid of this ring and contacted the XMM helpdesk and Read & Ponman, the authors of the background paper. However, up to this day, we did not entirely succeed to remove the brightness enhancement at the outer parts of the camera. Unfortunately, our results are somewhat sensitive to the uncertainty, as the radio galaxy 3C 129 is very large and occupies a rather large fraction of the XMM field of view. We are now working on a paper describing the results. The paper will include a detailed discussion of the uncertainties associated with the non- perfect background subtraction.

Krawczynski, Henric S. W.↗

Chandra Detection of a Parsec Scale Wind in the Broad Line Radio Galaxy 3C 382

We present unambiguous evidence for a parsec scale wind in the Broad-Line Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN whereby an outflow has been measured with X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C 382 has revealed the presence of several high ionization absorption lines in the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are blue-shifted with respect to the systemic velocity of 3C 382 by -840+/-60 km/s and are resolved by Chandra with a velocity width of sigma = 340+/-70 km/s. The outflow appears to originate from a single zone of gas of column density N(sub H) = 1.3 x 10(exp 21)/sq cm and ionization parameter log(E/erg/cm/s) = 2.45. From the above measurements we calculate that the outflow is observed on parsec scales, within the likely range from 10-1000 pc, i.e., consistent with an origin in the Narrow Line Region. Finally we also discuss the possibility of a much faster (0.1c) outflow component, based on a blue-shifted iron K(alpha) emission line in the Suzaku observation of 3C 382, which could have an origin in an accretion disk wind.

Reeves, J. N.↗