The optical and near-infrared polarization properties of the OVV quasar 3C 345

Smith, Paul S.; Balonek, T. J.; Heckert, P. A.; Elston, R.

doi:10.1086/164261

Cited by 40 publications

(25 citation statements)

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“…Broad‐band polarization and flux density spectra for this object do show the presence of two emission components (Wills 1991): one polarized, probably synchrotron jet radiation; and a second unpolarized, possibly from a disc. Optical and near‐infrared polarimetric and photometric monitoring also support the two‐continuum emission in this source (Smith et al 1986).…”

Section: Statistical Resultsmentioning

confidence: 69%

Is there a disc in the superluminal quasars?

Rokaki

Lawrence

Economou

et al. 2003

Monthly Notices of the Royal Astronomical Society

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We look for the expected signature of an accretion disc by examining the properties of the Hα emission line versus viewing angle in a sample of 22 superluminal (SL) quasars. The Doppler factor δ, jet velocity γ and viewing angle θ towards the jet are derived from published radio and X‐ray data. Most of the Hα spectra (14) have been observed at the United Kingdom Infrared Telescope (UKIRT) and are reported here. About a quarter of the SL objects have weak or absent Hα emission lines, with small equivalent widths (EW). These have high optical polarization, radio core dominance and Doppler factor, and most of them have high apparent SL velocity and low viewing angles. Therefore these weak‐EW objects almost certainly have relativistically beamed optical continua. The strong‐EW objects also show a clear beaming effect, but a much weaker one, with line EW varying by only a factor of 3 while radio core dominance varies by a factor of several hundred. The correlation of EW with θ is quantitatively in good agreement with the prediction of a flat accretion disc with limb darkening. The weak‐ and strong‐EW sources also show an anticorrelation of line velocity width with the various beaming indicators. Again, the correlation with the derived viewing angle θ shows a quantitative agreement with the effect expected for an axisymmetric structure with velocity dominated by rotation. The line emission cannot come from the surface of the disc, or the line beaming would cancel the continuum beaming. However, it could come from an axisymmetric system of clouds corotating with the accretion disc.

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Section: Statistical Resultsmentioning

confidence: 69%

Is there a disc in the superluminal quasars?

Rokaki

Lawrence

Economou

et al. 2003

Monthly Notices of the Royal Astronomical Society

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“…A possible candidate is the big blue bump (BBB) that dominates the UV-optical continuum of most strong broad emission-line AGNs (see, e.g., Malkan & Sargent 1982;Malkan 1983). The effect of the BBB (plus the smaller ''3000 8 bump''; Wills et al 1985) on the synchrotron polarization spectrum has been demonstrated for several optically violent variable quasars and 3C 273 (see, e.g., Smith et al 1986;Impey et al 1989;Wills et al 1992;Smith et al 1993b). In all of these cases, P decreases into the blue as the BBB becomes increasingly more important relative to the redder synchrotron spectrum.…”

Section: Effectiveness Of Bl Lac Object Selection From the Sdssmentioning

confidence: 99%

Highly Polarized Optically Selected BL Lacertae Objects

Smith

Williams

Schmidt

et al. 2007

ApJ

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Observations of candidate BL Lacertae objects spectroscopically selected from the Sloan Digital Sky Survey (SDSS) reveal a large fraction of objects with high polarizations (P > 3%). This result confirms that synchrotron radiation makes an important contribution to the observed optical continuum for most objects in the sample. The SDSS sample can be divided into separate categories, with objects of undetermined redshift generally having the highest optical polarization. Polarization as high as 23% and the lack of spectral features suggests that the synchrotron continuum completely dominates the spectra of these sources. The mean polarization levels observed for objects that have measured redshifts is much lower, with the maximum observed polarization for this group being $10%. The lower polarizations of these objects are reminiscent of the less spectacular polarization levels shown by BL Lac objects discovered in X-ray surveys. We find no SDSS BL Lac candidates at z k 1 with P > 3%, which calls their classification as BL Lac objects into question. In addition, the existence of radio-quiet BL Lac objects is not verified, since none of the 10 potentially radio-weak BL Lac candidates observed are highly polarized. Regardless of whether the high-redshift and radio-weak objects are included in this optical sample, the overall levels of polarization observed are intermediate between those seen for X-ray-and radio-selected BL Lac objects.

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“…Instead, many of these objects within the sample (e.g., PKS 0736+01, OJ248, PKS 1222+216, PKS 1510-08, B2 1633+382, 3C 454.3) are seen to harbor a blue, unpolarized continuum because of the fact that there is a systematic increase in P with wavelength (e.g., [12]). An observation of PKS 1222+216 made during a period of extremely high polarization that illustrates the polarization signature seen in many FSRQs is displayed in Figure 4b.…”

Section: Polarization As a Function Of Wavelengthmentioning

confidence: 99%

Sharp Polarimetric Eyes: More Trees than Forest?

Smith

2016

Galaxies

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Abstract:The Fermi Gamma-ray Space Telescope (Fermi) has focused the intensive multi-wavelength and international observational effort on blazars since it was launched in 2008. Part of this effort involves systematic monitoring of the highly variable polarization of the continuum emission from these objects. These observations are valuable in that they provide direct information on the degree of ordering and orientation on the sky of the magnetic field within the non-thermal emission region(s). Unfortunately, it is not yet possible to measure the polarization of the inverse-Compton continuum, only that of the lower-energy synchrotron emission. The inability to directly compare the polarization of the two dominant continuum sources in blazars is a drawback and leads to more ambiguities in determining their relative locations. There are many compelling examples of strong connections between γ-ray, X-ray, UV/optical/IR, and radio behavior in blazars that suggest the same region produces much of the observed emission at all wavelengths at least some of the time. However, the wealth of polarization behavior seen relative to flux changes invariably results in a complex situation that is difficult to interpret and model. The long-term blazar monitoring program undertaken at Steward Observatory is designed to primarily obtain accurate optical polarimetry of γ-ray-bright blazars during the Fermi mission with the goal of gaining important insights into the jet structure and physics of these objects. Data from this program are available to all researchers as soon as reductions are completed. I briefly detail the current status and progress of the program and the data products available. Although the wide variety of polarization behavior in blazars adds another layer of complexity to an already difficult problem, I summarize several important conclusions that can be drawn from the polarization information gathered during the Fermi era.

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The optical and near-infrared polarization properties of the OVV quasar 3C 345

Cited by 40 publications

References 0 publications

Is there a disc in the superluminal quasars?

Is there a disc in the superluminal quasars?

Highly Polarized Optically Selected BL Lacertae Objects

Sharp Polarimetric Eyes: More Trees than Forest?

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