Related papers: VLTI-GRAVITY observations of blazars
(Shortened)Context: We analyze the optical variability of the FSRQ Ton 599 using BVRI photometry from the WEBT collaboration (2011-2023), complemented by photometric and spectroscopic data from the Steward Observatory.\\ Aims: To…
We study the broad emission line blazars detected in the gamma-ray band by the Large Area Telescope onboard the Fermi satellite and with the optical spectrum studied by Shaw et al. (2012, 2013). The observed broad line strength provides a…
Blazars are known to emit exceptionally variable non-thermal emission over the wide range (from radio to $\gamma$-rays) of electromagnetic spectrum. We present here the results of our $\gamma$-ray flux and spectral variability study of the…
Blazars represent the most abundant class of high-energy extragalactic $\gamma$-ray sources. The subset of blazars known as BL Lac objects is on average closer to Earth and characterized by harder spectra at high energy than the whole…
We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of gamma-ray sources in the Fermi 2FGL…
GRAVITY is the four-beam, near- infrared, AO-assisted, fringe tracking, astrometric and imaging instrument for the Very Large Telescope Interferometer (VLTI). It is requiring the development of one of the most complex instrument software…
We present Very Long Baseline Array (VLBA) images of 20 TeV blazars (HBLs) not previously well-studied on the parsec scale. Observations were made between August and December 2013, at a frequency of 8.4 GHz. These observations represent the…
Context : The properties of the inner disks of bright Herbig AeBe stars have been studied with near infrared (NIR) interferometry and high resolution spectroscopy. The continuum and a few molecular gas species have been studied close to the…
In this paper, we study the feasibility of obtaining near-infrared spectra of bright extrasolar planets with the 2nd generation VLTI Spectro-Imager instrument (VSI), which has the required angular resolution to resolve nearby hot Extrasolar…
The extragalactic high-energy $\gamma$-ray sky is dominated by blazars, which are active galactic nuclei with their jets pointing towards us. Distance measurements are of fundamental importance yet for some of these sources are challenging…
TeV-emitting BL Lac type blazars represent the extreme end of the blazar population. They are characterized by relatively weak jets and radiatively inefficient accretion disks. Particles accelerated in these jets experience fewer radiative…
Ever since the discovery by the Fermi mission that active galactic nuclei (AGN) produce copious amounts of high-energy emission, its origin has remained elusive. Using high-frequency radio interferometry (VLBI) polarization imaging, we…
The extragalactic gamma-ray sky is dominated by relativistic jets aligned to the observer's line of sight, i.e., blazars. A few of their misaligned counterparts, e.g., radio galaxies, are also detected with the Fermi-Large Area Telescope…
The production site and process responsible for the highly variable high-energy emission observed from blazar jets are still debated. Gravitational lenses can be used as microscopes to investigate the nature of such sources. We study the…
We present analysis of the flux and polarization variability of parsec scale radio jets from a dual-frequency, six-epoch, VLBA polarization experiment monitoring 12 blazars. The observations were made at 15 and 22 GHz at bimonthly intervals…
We present new VLTI/GRAVITY near-infrared interferometric measurements of the angular size of the innermost hot dust continuum for 14 type 1 AGNs. The angular sizes are resolved on scales of ~0.7 mas and the inferred ring radii range from…
The dominant fraction of the extragalactic $\gamma$-ray sources are blazars, active galactic nuclei with jets inclined at a small angle to the line of sight. Apart from blazars, a few dozen narrow-line Seyfert 1 galaxies (NLS1) and a number…
We give a progress report on a snapshot 86 GHz-VLBI survey of the EGRET blazars with the observatories of the CMVA. A high fraction (17/18) of the EGRET blazars were detected on the Pico Veleta-Onsala baseline with a baseline length on the…
We present a new gravitational lens modelling technique designed to model high-resolution interferometric observations with large numbers of visibilities without the need to pre-average the data in time or frequency. We demonstrate the…
The variability in the infrared to millimetre emission from microquasar GRS 1915+105 is believed to be dominated by the system's relativistic jet. In this paper we develop a time-dependent version of the Blandford & Koenigl (1979) jet…