Polarization observation of compact extragalactic objects

Babadzhanyants, M. K.; Hagen-Thorn, V. A.

doi:10.1007/bf01002591

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…The image reduction process included bias, flat-field corrections, cosmic ray removal, 2D wavelength linearization, background subtraction, stacking of the spectra for every set up, and flux calibration. Neizvestny (1986); large filled circles -photometry (present paper); open squares - Yee & Oke (1981); small filled circles - Babadzhanyants et al (1973Babadzhanyants et al ( , 1974Babadzhanyants et al ( , 1975Babadzhanyants et al ( , 1976Babadzhanyants et al ( , 1984; crosses - Cannon et al (1971), Scott et al (1976), Selmes et al (1975), Pica et al (1980); plusses -spectral continuum (present paper); open triangles - Dietrich et al (1998); filled trianglesspectral cont. from Perez et al (1988) and Lawrence et al (1996).…”

Section: Observationsmentioning

confidence: 85%

Intermediate Resolution Hβ Spectroscopy and Photometric Monitoring of 3C 390.3. I. Further Evidence of a Nuclear Accretion Disk

Shapovalova¹,

Буренков²,

Spiridonova³

et al. 2002

International Astronomical Union Colloquium

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We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-Band light curve dating back to 1966, shows a large increase in brightness during 1970 -1971, followed by a gradual decrease down to a minimum in 1982. During the 1995-2000 lapse the broad Hβ emission and the continuum flux varied by a factor of ≈ 3. Two large amplitude outbursts, of different duration, in continuum and Hβ light were observed ie.: in October 1994 a brighter flare that lasted ≈1000 days and in July 1997 another one that lasted ≈ 700 days were detected. The response time lag of the emission lines relative to flux changes of the continuum, has been found to vary with time ie. during 1995-1997 a lag of about 100 days is evident, while during 1998-1999 a double valued lag of ≈ 100 days and ≈ 35 days is present in our data. The flux in the Hβ wings and line core vary simultaneously, a behavior indicative of predominantly circular motions in the BLR. Important changes of the Hβ emission profiles were detected: at times, we found profiles with prominent asymmetric wings, as those normaly seen in Sy1s, while at other times, we observe profiles with weak almost symmetrical wings, similar to those of Sy1.8s. We further dismiss the hypothesis that the double peaked Hβ profiles in this object originate in a massive binary BH. Instead, we found that the radial velocity difference between the red and blue bumps is anticorrelated with the light curves of Hβ and continuum radiation. This implies that the zone that contributes with most of the energy to the emitted line, changes in radius within the disk. The velocity difference increases, corresponding to smaller radii, as the continuum flux decreases. When the continuum flux increases the hump velocity difference decreases. These transient phenomena are expected to result from the variable accretion rate close to the central source. The optical continuum and the Hβ flux variations might be related to changes in X-ray emission modulated by a variable accretion rate, changing the surface temperature of the disk, as a result of a variable X-ray irradiation ( Ulrich, 2000). Theoretical Hβ profiles were computed for an accretion disk, the observed profiles are best reproduced by an inclined disk (25 • ) whose region of maximum emission is located roughly at 200 Rg. The mass of the black hole in 3C 390.3, estimated from the reverberation analysis is Mrev ≈ 2.1 × 10 9 M ⊙ , 5 times larger than previous estimates (Wandel et al.1999).

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Section: Observationsmentioning

confidence: 85%

Intermediate Resolution Hβ Spectroscopy and Photometric Monitoring of 3C 390.3. I. Further Evidence of a Nuclear Accretion Disk

Shapovalova¹,

Буренков²,

Spiridonova³

et al. 2002

International Astronomical Union Colloquium

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“…It was therefore natural to search for polarization of the optical emission of Seyfert galaxies (Dibai & Shakhovskoy 1966). Optical polarization of NGC 4151 was discovered by Babadzhanyants & Hagen-Thorn (1969) who also reported that the polarization was variable. The polarization was studied in more detail by Kruszewski (1971) who found that the polarization in the V band varied by a factor of four over a nine-month period.…”

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confidence: 94%

Discovery of Polarization Reverberation in NGC 4151

Gaskell

Goosmann

Меркулова

et al. 2012

ApJ

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Observations of the optical polarization of NGC 4151 in 1997NGC 4151 in -2003 show variations of an order of magnitude in the polarized flux while the polarization position angle remains constant. The amplitude of variability of the polarized flux is comparable to the amplitude of variability of the total U -band flux, except that the polarized flux follows the total flux with a lag of 8 ± 3 days. The time lag and the constancy of the position angle strongly favor a scattering origin for the variable polarization rather than a non-thermal synchrotron origin. The orientation of the position angle of the polarized flux (parallel to the radio axis) and the size of the lag imply that the polarization arises from electron scattering in a flattened region within the low-ionization component of the broad-line-region. Polarization from dust scattering in the equatorial torus is ruled out as the source of the lag in polarized flux because it would produce a larger lag and, unless the half-opening angle of the torus is >53 • , the polarization would be perpendicular to the radio axis. We note a long-term change in the percentage of polarization at similar total flux levels and this could be due either to changing non-axisymmetry in the optical continuum emission, or a change in the number of scatterers on a timescale of years.

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“…Another important property of AGN is their variability, a property first discovered in the late 1960s (Cannon et al 1968;Kinman 1968;Pacholczyk and Wyemann 1968;Barnes 1968;Selove 1969;Zaitseva and Lyutyi 1969;Babadzhanyants and Hagen-Thorn 1969) in the optical, and a couple years later in the radio (Stull 1970;Ross 1970). This variability has since been found to extend to all wavebands (see Ulrich et al 1997 for a review), in both continuum and line emission.…”

Section: Variabilitymentioning

confidence: 97%

Planets, Stars and Stellar Systems

Oswalt¹,

Keel²

2013

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Polarization observation of compact extragalactic objects

Cited by 5 publications

References 4 publications

Intermediate Resolution Hβ Spectroscopy and Photometric Monitoring of 3C 390.3. I. Further Evidence of a Nuclear Accretion Disk

Intermediate Resolution Hβ Spectroscopy and Photometric Monitoring of 3C 390.3. I. Further Evidence of a Nuclear Accretion Disk

Discovery of Polarization Reverberation in NGC 4151

Planets, Stars and Stellar Systems

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