395 citations · 5.4k across the 130 of their papers we have counts for
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The radio emission in radio-quiet quasars: the VLBA perspective
Sina Chen, Ari Laor, Ehud Behar +2
The origin of the radio emission in radio-quiet quasars (RQQ) is not established yet. We present new VLBA observations at 1.6 and 4.9 GHz of ten RQQ (nine detected), which together…
Transient obscuration event captured in NGC 3227 IV. Origin of the obscuring cloud variability
S. Grafton-Waters, J. Mao, M. Mehdipour +13
Obscuration events in type I active galactic nuclei (AGN) have been detected more frequently in recent years. The strong flux decrease in the soft X-ray band between observations h…
Dependence of the Radio Emission on the Eddington Ratio of Radio-Quiet Quasars
A. Alhosani, J. D. Gelfand, I. Zaw +4
Roughly 10% of quasars are "radio-loud", producing copious radio emission in large jets. The origin of the low-level radio emission seen from the remaining 90% of quasars is unclea…
Quasi-simultaneous observations of radio and X-ray variability in three radio-quiet Seyfert galaxies
Sina Chen, Ari Laor, Ehud Behar
Radio variability in some radio-quiet (RQ) active galactic nuclei suggests emission from regions close to the central engine, possibly the outer accretion disc corona. If the origi…
Radio spectra of narrow-line Seyfert 1 galaxies observed with ATCA and VLASS
Sina Chen, Jamie B. Stevens, Philip G. Edwards +7
We present radio spectral analyses for a sample of 29 radio-quiet (RQ) and three radio-loud (RL) narrow-line Seyfert 1 galaxies (NLS1s) detected with the Australia Telescope Compac…
Transient obscuration event captured in NGC~3227 II. Warm absorbers and obscuration events in archival XMM-Newton and NuSTAR observations
Yijun Wang, Jelle Kaastra, Missagh Mehdipour +18
The relation between warm absorber (WA) outflows of AGN and nuclear obscuration activities caused by optically-thick clouds (obscurers) crossing the line of sight is unclear. NGC 3…
The Great Slump: Mrk926 reveals discrete and varying Balmer line satellite components during a drastic phase of decline
Wolfram Kollatschny, Martin W. Ochmann, Shai Kaspi +9
Mrk926 is known to be a highly variable AGN with very broad line profiles. We studied the continuum and line profile variations of this object with high temporal resolution in orde…
The PG-RQS survey. Building the radio spectral distribution of radio-quiet quasars. I. The 45-GHz data
R. D. Baldi, A. Laor, E. Behar +4
The origin of the radio emission in radio-quiet quasars (RQQs) remains unclear. Radio emission may be produced by a scaled-down version of the relativistic jets observed in radio-l…
Hard - X-rays selected Active Galactic Nuclei. I. A radio view at high-frequencies
E. Chiaraluce, F. Panessa, G. Bruni +5
A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay…
The ionic composition of the local absorber towards 3C 273
Itay Gissis, Uria Peretz, Ehud Behar
Hot ionized gas is observed in the local vicinity of our galaxy through spectral absorption features. The most common hypothesis is that this gas forms a halo surrounding our Milky…
Multi-wavelength campaign on NGC 7469 V. Analysis of the HST/COS observations: Super solar metallicity, distance, and trough variation models
N. Arav, X. Xu, G. A. Kriss +18
Aims. Our aim is to determine the distance of the UV outflow components from the central source, their abundances and total column density, and the mechanism responsible for their…
Multi-wavelength Campaign on NGC 7469 VI. Photoionisation Modelling of the Emission Line Regions and the Warm Absorber
S. Grafton-Waters, G. Branduardi-Raymont, M. Mehdipour +16
Aims. We aim to investigate and characterise the photoionised X-ray emission line regions within NGC 7469. Methods. We apply the photoionisation model, PION, within the spectral fi…
The physics and astrophysics of X-ray outflows from Active Galactic Nuclei
Sibasish Laha, Randall Smith, Panayiotis Tzanavaris +20
The highly energetic outflows from Active Galactic Nuclei detected in X-rays are one of the most powerful mechanisms by which the central supermassive black hole (SMBH) interacts w…
Direct observation of the Broad Line Region in X-rays during the low state of NGC4051
Uria Peretz, Jon M. Miller, Ehud Behar
NGC 4051 is one of the X-ray brightest and most variable Seyfert galaxies. During 2009 NGC 4051 was caught at its lowest state ever observed by . The low source continu…
The Origin of Radio Emission from Radio-Quiet AGN
Francesca Panessa, Ranieri D. Baldi, Ari Laor +3
The central nuclei of galaxies, where super-massive black holes (SMBHs) are thought to reside, can experience phases of activity when they become Active Galactic Nuclei (AGN). An A…
What drives the radio slopes in radio quiet quasars?
Ari Laor, Ranieri D. Baldi, Ehud Behar
The origin of the radio emission in Radio Quiet (RQ) quasars is not established yet. Important hints can be provided by the spectral slope, and its relation to other emission prope…
Classifying AGN by X-ray Hardness Variability
Uria Peretz, Ehud Behar
The physics behind the dramatic and unpredictable X-ray variability of Active Galactic Nuclei (AGN) has eluded astronomers since it was discovered. We present an analysis of Swift…
The mm-wave compact component of AGN
Ehud Behar, Stuart Vogel, Ranieri D. Baldi +2
mm-wave emission from Active Galactic Nuclei (AGN) may hold the key to understanding the physical origin of their radio cores. The correlation between radio/mm and X-ray luminosity…
Observational Evidence Linking Interstellar UV Absorption to PAH Molecules
Avi Blasberger, Ehud Behar, Hagai B. Perets +2
The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by Polycyclic Aromatic Hydrocarbon…
Radio-loud Narrow Line Seyfert 1 under a different perspective: a revised black hole mass estimate from optical spectropolarimetry
Ranieri D. Baldi, Alessandro Capetti, Andrew Robinson +2
Several studies indicate that radio-loud (RL) Active Galactic Nuclei (AGN) are produced only by the most massive black holes (BH), -. This id…
Millimeter-band variability of the radio-quiet nucleus of NGC7469
Ranieri D. Baldi, Ehud Behar, Ari Laor +1
We report short-cadence monitoring of a radio-quiet Active Galactic Nuclei (AGN), NGC7469, at 95 GHz (3 mm) over a period of 70 days with the CARMA telescope. The AGN varies signif…
Discovery of Millimeter-Wave Excess Emission in Radio-Quiet Active Galactic Nuclei
Ehud Behar, Ranieri D. Baldi, Ari Laor +3
The physical origin of radio emission in Radio Quiet Active Galactic Nuclei (RQ AGN) remains unclear, whether it is a downscaled version of the relativistic jets typical of Radio L…
Anatomy of the AGN in NGC 5548: II. The Spatial, Temporal and Physical Nature of the Outflow from HST/COS Observations
N. Arav, C. Chamberlain, G. A. Kriss +30
(Abridged) Our deep multiwavelength campaign on NGC 5548 revealed an unusually strong X-ray obscuration. The resulting dramatic decrease in incident ionizing flux allowed us to con…
The Herschel Planetary Nebula Survey (HerPlaNS) I. Data Overview and Analysis Demonstration with NGC 6781
T. Ueta, D. Ladjal, K. M. Exter +30
This is the first of a series of investigations into far-IR characteristics of 11 planetary nebulae (PNs) under the Herschel Space Observatory Open Time 1 program, Herschel Planeta…