A5020885808- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Dark Matter and Cosmic Phenomena
- Calibration and Measurement Techniques
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Magnetic confinement fusion research
- Particle physics theoretical and experimental studies
- Astro and Planetary Science
- Neutrino Physics Research
- Atmospheric Ozone and Climate
- Gyrotron and Vacuum Electronics Research
- Optical and Acousto-Optic Technologies
- Optical Systems and Laser Technology
- Particle Detector Development and Performance
National Institute of Astrophysics, Optics and Electronics
2015-2024
Center for Astrophysics Harvard & Smithsonian
2022-2024
L. A. Orbeli Institute of Physiology NAS RA
2023-2024
Laboratório Nacional de Astrofísica
2002-2014
University of Belgrade
2013
Max Planck Institute for Astrophysics
2013
Special Astrophysical Observatory
1997-2013
Astronomical Observatory
2013
Universidad Nacional Autónoma de México
2006-2008
Byurakan Astrophysical Observatory
1997-1998
ABSTRACT OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in binary black hole model. The model predicted major outburst 2015 December. We found the did occur within expected time range, peaking on December 5 at magnitude 12.9 R -band. Based Swift /XRT satellite measurements and polarization data, we find it included thermal component. Its timing provides an accurate estimate for spin of primary hole, . present also...
Abstract We present the results of prompt optical follow-up electromagnetic counterpart gravitational-wave event GW170817 by Transient Optical Robotic Observatory South Collaboration. detected highly significant dimming in light curves ( mag, mag) over course only 80 minutes observations obtained ∼35 hr after trigger with T80-South telescope. A second epoch observations, ∼59 EABA 1.5 m telescope, confirms fast fading nature transient. The observed colors suggest that this was a “blue...
Abstract Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission gravitational waves (GWs). We show that observations associated binary black hole (BBH) central engine blazar OJ 287 demand inclusion radiation reaction effects beyond quadrupolar order. It turns out even certain hereditary contributions to GW required predict impact flare timings 287. develop an approach incorporates this effect into BBH...
We present the final installment of an intensive 13 year study variations optical continuum and broad Hβ emission line in Seyfert 1 galaxy NGC 5548. The database consists 1530 measurements 1248 measurements. follow closely, with a typical time delay about 20 days. However, year-by-year analysis shows that magnitude emission-line is correlated mean flux. argue data are consistent simple model prediction between size broad-line region ionizing luminosity, r ∝ L. Moreover, apparently linear...
We report the detection of a statistically significant flare-like event in Mg II\lambda 2800\AA\ emission line 3C 454.3 during outburst autumn 2010. The highest levels flux recorded over monitoring period (2008 - 2011) coincide with superluminal jet component traversing through radio core. This finding crucially links broad-emission fluctuations to non-thermal continuum produced by relativistically moving material and hence presence broad-line region clouds surrounding If core were located...
We present optical and near infrared (NIR) imaging data of the radio-loud Narrow-line Seyfert 1 galaxy 1H 0323+342, which shows intense variable gamma-ray activity discovered by Fermi satellite with Large Area Telescope. NIR images are used to investigate structural properties host 0323+342; this together spectroscopy allowed us examine its black hole mass. Based on 2D multiwavelength surface brightness modeling, we find that, statistically, best model fit is a combination nuclear component...
We present two catalogs of radio-loud candidate blazars whose WISE mid-infrared colors are selected to be consistent with the confirmed gamma-ray emitting blazars. The first catalog is improved and expanded release WIBRaLS presented by D'Abrusco et al. (2014): it includes sources detected in all four filters, spatially cross-matched radio source one three surveys based on their q22 spectral parameter. WIBRaLS2 9541 classified as BL Lacs, FSRQs or mixed candidates colors. second catalog,...
Blazars, one of the most extreme class active galaxies, constitute so far largest known population $\gamma$-ray sources and their number is continuously growing in Fermi catalogs. However latest release catalog there still a large fraction that are classified as blazar candidate uncertain type (BCUs) for which optical spectroscopic observations necessary to confirm nature associations. In addition about 1/3 point listed Third Fermi-LAT Source Catalog (3FGL) unassociated lacking an assigned...
<i>Aims. <i/>We present the results of a long-term monitoring (11 years, between 1996 and 2006) H<i>α<i/> H<i>β<i/> line variations active galactic nucleus NGC 4151.<i>Methods. <i/>High quality spectra (<i>S<i/>/<i>N<i/> > 50 <i>R<i/><i>≈<i/> 8 Å) were investigated. During period, we analyzed profile variations. Comparing profiles H<i>β<i/>, studied different details (bumps, absorbtion features) in profiles. The segments We also Balmer decrement for entire lines segments. <i>Results. found...
A significant fraction ($\sim 30$ %) of the gamma-ray sources listed in second $\textit{Fermi}$ LAT (2FGL) catalog is still unknown origin, being not yet associated with counterparts at lower energies. Using available information energies and optical spectroscopy on selected these objects we can pinpoint their exact nature. Here present a pilot project pointing to assess effectiveness several classification methods developed select blazar candidates. To this end, report spectroscopic...
The extragalactic $\gamma$-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei (AGNs). Many the sources included in Fermi -Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidate uncertain type (BCU) because there no optical spectra available literature to confirm their nature. In 2013 we started spectroscopic campaign look for counterparts BCUs and Unidentified Sources. main goal our investigation nature these having...
The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in 2010 February and the Fermi-LAT 2-Year (2FGL) appeared 2012 April, based on data from 24 months of operation. Since they were released, many follow up observations unidentified γ-ray sources have been performed new procedures for associating with potential counterparts at other wavelengths developed. Here we review characterize all associations as published 1FGL 2FGL catalogs basis multifrequency archival...
We present an analysis of 43 years (1972 to 2015) spectroscopic observations the Seyfert 1 galaxy NGC 5548. This includes 12 new unpublished (2003 2015). compiled about 1600 H$\beta$ spectra and analyzed long-term spectral variations 5100 \AA\ continuum line. Our is based on standard procedures including Lomb-Scargle method, which known be rather limited such heterogeneous data sets, method developed specifically for this project that more robust reveals a $\sim$5700 day periodicity in light...
Here we present the long-term optical spectral monitoring of a changing-look active galactic nuclei (AGN) NGC 3516 that covers 22 years (from 1996 to 2018). We explore variability in broad lines and continuum, finding continuum is changing by more than factor 2, while are varying 10. The minimum activity observed 2014, when almost disappeared. confirm AGN, absorption seen UV X-ray may indicate there an obscuring region which responsible for this. line profiles also changing. mean Halpha...
Abstract The flat spectrum radio quasar PKS 1510−089 is one of the most active blazars across entire electromagnetic spectrum, displaying periods flaring activity. This study explores its spectral variability over a decade. By employing nonthermal dominance parameter, we analyze H β and λ 5100 continuum light curves, as well FWHM emission line, to identify whether primary source accretion disk or jet during activity periods. Our results show an anticorrelation between luminosity line all...
The flat spectrum radio quasar 3C 454.3 is known for its high variability across the electromagnetic spectrum, showing structural and flux in parsec-scale jet correlated among frequency bands. This study aims to identify structure, dynamics, radiative processes common innermost regions of blazar 454.3. We investigate whether any component can be associated with γ-ray emission variability. Additionally, we compare components found VLBA observations emission. analyzed relationship between...
(abridged) Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among detected sources. Here we continue our identification program selecting probable optical candidates using positional cross-correlation with soft X-ray, radio, and/or archives, and performing spectroscopy on them. As result, identified or more accurately characterized 44 counterparts sources: 32 active galactic nuclei, redshift 0.019 < z 0.6058,...
Within the framework of our program assessment nature unidentified or poorly known <i>INTEGRAL<i/> sources, we present here spectroscopy optical objects, selected through positional cross-correlation with soft X-ray detections (afforded satellites such as <i>Swift<i/>, <i>ROSAT<i/>, <i>Chandra<i/> and/or <i>XMM-Newton<i/>) putative counterparts hard sources detected IBIS instrument onboard <i>INTEGRAL<i/>. Using 6 telescopes various sizes and archival data from two on-line spectroscopic...
The mechanism and the region of generation variable continuum emission are poorly understood for radio-loud active galactic nuclei because complexity nuclear region. High-resolution radio very long baseline interferometry (VLBI) observations have allowed us to zoom into a subparsec-scale jet in galaxy 3C 390.3. We combined VLBI optical data covering time period 14 yr order look link between flares parsec-scale jet. identified two stationary nine moving features innermost All ejections...
We report Hubble Space Telescope imaging, obtained 155 and 449 days after the 2006 outburst of recurrent nova RS Ophiuchi, together with ground-based spectroscopic observations, from Observatorio Astron\'omico Nacional en San Pedro M\'artir, Baja California, M\'exico at Astrof\'isico Guillermo Haro, Cananea, Sonora, M\'exico. The observations first epoch were used as inputs to model geometry kinematic structure evolving Oph nebular remnant. find that modeled remnant comprises two distinct...
We present the results of a long-term (1999--2010) spectral optical monitoring campaign active galactic nucleus (AGN) Ark 564, which shows strong Fe II line emission in optical. This AGN is narrow Seyfert 1 (NLS1) galaxies, group AGNs with specific characteristics. analyze light curves permitted Ha, Hb, fluxes, and continuum flux order to search for time lag between them. Additionally, estimate contribution iron lines from different multiplets, we fit Hb sum Gaussian components. found that...
Within the framework of our program (running since 2004) identification hard X-ray INTEGRAL sources through optical spectroscopy, we present results concerning nature 33 high-energy objects. The data were acquired with use six telescopes different sizes and from one on-line archive. indicate that majority these objects (23 out 33) are active galactic nuclei (AGNs), whereas 10 in local Universe eight which Galaxy two Small Magellanic Cloud (SMC). Among identified AGNs, 13 Type 1 (i.e., broad...
Supermassive black holes launching plasma jets at close to speed of light, producing gamma-rays, have ubiquitously been found be hosted by massive elliptical galaxies. Since galaxies are generally believed built through galaxy mergers, active galactic nuclei (AGN) relativistic associated the latest stages evolution. We discovered a pseudo-bulge morphology in host gamma-ray AGN PKS 2004-447. This is first emitter radio loud launched from system where both hole and actively growing via secular...
Until recently, relativistic jets were ubiquitously found to be launched from giant elliptical galaxies. However, the detection by Fermi-LAT of gamma-ray emission radio-loud narrow-line Seyfert 1 (RL-NLSy1) galaxies raised doubts on this relation. Here, we morphologically characterize a sample 29 RL-NLSy1s (including 12 emitters, gamma-NLSy1s) in order find clues conditions needed AGN produce jets. We use deep near-infrared images Nordic Optical Telescope and ESO VLT analyze surface...