Н. В. Ефимова
A5037638872- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Particle physics theoretical and experimental studies
- Gyrotron and Vacuum Electronics Research
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Mechanics and Biomechanics Studies
- Atomic and Subatomic Physics Research
Pulkovo Observatory
2015-2024
St Petersburg University
2006-2016
Institute of Applied Astronomy
2006-2015
Southampton City Council
2015
Russian Academy of Sciences
2008-2009
We present the results of one-year long observational campaign type II plateau SN 2005cs, which exploded in nearby spiral galaxy M51 (the Whirlpool galaxy). This extensive data set makes 2005cs best observed low-luminosity, 56Ni-poor event so far and one core-collapse supernovae ever. The optical near-infrared spectra show narrow P-Cygni lines characteristic this family, are indicative a very low expansion velocity (about 1000 km s−1) ejected material. light curves cover both phase late-time...
We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during first two years Fermi Gamma-ray Space Telescope mission. While investigating previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that emission appears delayed with respect to gamma-ray about 10 days. X-ray reveal pair `isolated' flares separated ~90 days, only weak counterparts. The spectral structure measured...
We analyze the multifrequency behavior of quasar 3C 454.3 during three prominent \gamma-ray outbursts: 2009 Autumn, 2010 Spring, and Autumn. The data reveal a repeating pattern, including triple flare structure, in properties each outburst, which implies similar mechanism(s) location for all events. multi-frequency indicates that lower frequency events are co-spatial with outbursts, although emission varies on shortest timescales. determine variability from UV to IR wavelengths an outburst...
ABSTRACT We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multiwavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters ( BVRI and ugriz ). Combined with ultraviolet the Hubble Space Telescope Swift , we confirm significant time delays between continuum bands as a function wavelength, extending wavelength coverage 1158 Å z band (~9160 Å). find that lags at wavelengths longer...
Since the launch of Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when source started a series strong flares. The exceptional sampling achieved by GLAST-AGILE Support Program (GASP) Whole Earth Blazar Telescope (WEBT) in collaboration with Steward Observatory allows us to perform detailed comparison daily gamma-ray observations Fermi. Discrete correlation analysis between emission reveals time lag 0 +- 1 d, which suggests...
The radio quasar 3C 454.3 underwent an exceptional optical outburst lasting more than 1 year and culminating in spring 2005. maximum brightness detected was R = 12.0, which represents the most luminous state thus far observed (M_B ~ -31.4). In order to follow emission behaviour of source detail, a large multiwavelength campaign organized by Whole Earth Blazar Telescope (WEBT). Continuous optical, near-IR monitoring performed several bands. ToO pointings Chandra INTEGRAL satellites provided...
BL Lacertae has been the target of four observing campaigns by Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present $UBVRI$ light curves obtained WEBT from 1994 to 2002, including last, extended Lac 2001 campaign. A total about 7500 optical observations performed 31 telescopes Japan Mexico have collected, be added $\sim 15600$ Campaign 2000. All these data allow one follow source emission behaviour with unprecedented detail. The analysis colour indices reveals that...
We present optical, X-ray, high energy ($\lessapprox 30$ GeV) and very ($\gtrapprox 100$ GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 June 23. A $\gamma$-ray signal was detected by AGILE with \sqrt{TS}=4.5 on 9--15, $F(E>100 \mathrm{MeV})= 42^{+14}_{-12}\times 10^{-8}$ photons cm$^{-2}$ s$^{-1}$. This flaring state is brighter than average flux observed EGRET a factor $\sim$3, but still consistent highest flux. In hard X-rays (20-60 keV)...
Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during last four years it exhibited more than one γ-ray flare per year, becoming most active in sky. We present for first time multi-wavelength AGILE, Swift, INTEGRAL, GASP-WEBT data collected order to explain extraordinary of which occurred 2010 November. On November 20 (MJD 55520), reached a peak flux (E >100 MeV) Fpγ = (6.8 ± 1.0) × 10−5 photons cm−2 s−1 on timescale about 12 hr, factor six...
Context. Over the past few years, on several occasions, large, continuous rotations of electric vector position angle (EVPA) linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy γ-ray flares and they attracted considerable attention, since could allow us to probe magnetic field structure in emitting region jet. The flat-spectrum radio quasar 3C 279 is one most prominent examples showing this behaviour.
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved almost daily cadence with observations from five ground-based telescopes. H$\beta$ He II $\lambda$4686 broad emission-line light curves lag that 5100 $\AA$ continuum by $4.17^{+0.36}_{-0.36}$ days $0.79^{+0.35}_{-0.34}$ days, respectively. relative to 1158 ultraviolet curve measured Hubble Space...
The blazar 3C 454.3 underwent an unprecedented optical outburst in spring 2005. This was first followed by a mm and then cm radio outburst, which peaked February 2006. We report on follow-up observations the WEBT to study multiwavelength emission post-outburst phase. XMM-Newton July December 2006 added information X-ray UV fluxes. source faint state. flux at higher frequencies showed fast decreasing trend, represents tail of big outburst. It quiescent state, common all frequencies. In...
We present the results of polarimetric (R-band) and multicolor photometric (BH RI J H K) observations blazar AO 0235+16 during an outburst in 2006 December. The data reveal a short timescale variability (several hours), which increases from optical to near-IR wavelengths; even shorter variations are detected polarization. flux density correlates with degree polarization, at maximum polarization electric vector tends align parsec-scale jet direction. find that variable component steady...
The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, Fermi. We analyse these data with particular attention to calibration Swift UV data, apply a helical jet model interpret source broad-band variability. GASP-WEBT show an flare 2008 February-March, oscillations several tenths mag on few-day time scale...
We present multiwavelength observations of 3C 454.3 from April 2008 to March 2010. The radio optical data are mostly the GASP-WEBT, UV and X-ray Swift, gamma-ray AGILE Fermi satellites. improved calibration optical-UV UVOT OM instruments estimated Lyalpha flux disentangle contributions different components in this spectral region. reveal prominent variability above 8 GHz. In band, amplitude decreases with increasing frequency due a steadier radiation both broad line region an accretion disc....
The quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum. We present results of low-energy multifrequency monitoring by GASP project WEBT consortium and collaborators, as well those spectropolarimetric/spectrophotometric at Steward Observatory. also analyse high-energy observations Swift Fermi satellites. In optical-UV band, several indicate that there is contribution from QSO-like emission...
ABSTRACT During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert 1 galaxy NGC 5548 performed from 2014 February to July, normally highly correlated far continuum and broad emission line variations decorrelated for ∼60–70 days, starting ∼75 days after first HST /COS observation. Following this anomalous state, flux variability lines returned a more normal state. This transient behavior, characterized by significant deficits in...
We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate temperature structure its accretion disk. The 19 overlapping light curves (1158 9157 angstroms) combine simultaneous HST , Swift and ground-based observations over 180 day period from 2014 January July. Light-curve is interpreted as reverberation response disk irradiation by central time-varying point source. Our model yields inclination, i, T1 at black hole, temperature-radius slope,...
A multifrequency campaign on the BL Lac object PG 1553+113 was organized by Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim to study source behaviour at low energies during around high-energy observations Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes April-July. We also analyse UV X-ray data acquired Swift XMM-Newton satellites same period. WEBT satellite allow us detail synchrotron emission...
Aims.A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by Whole Earth Blazar Telescope (WEBT) in 2003–2005 to study variability properties of source.
Context.Some intra-day variable, compact extra-galactic radio sources show brightness temperatures severely exceeding 1012 K, the limit set by catastrophic inverse-Compton (IC) cooling in of incoherent synchrotron radiation. The violation IC limit, actually possible under non-stationary conditions, would lead to avalanches soft-γ-ray energy band during transient periods.