- ID:
- ivo://CDS.VizieR/J/ApJ/569/23
- Title:
- Optical polarisation of 2MASS QSOs
- Short Name:
- J/ApJ/569/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical broadband polarimetry is presented for near-infrared color-selected active galactic nuclei (AGNs) classified as quasi-stellar objects (QSOs) based on their Ks-band luminosity. More than 10% of a sample of 70 QSOs discovered in the Two Micron All Sky Survey (2MASS, Cat. <B/2mass>) with J-Ks>2 and M_Ks_<-23 show high broadband linear polarization (P>3%), and values range to a maximum of P~11%. High polarization tends to be associated with the most luminous objects at Ks and with QSOs having the highest near-IR to optical flux ratios. The 2MASS QSO sample includes objects possessing a wide range of optical spectral types. High polarization is seen in two of 22 broad emission-line (type 1) objects, but ~1/4 of the QSOs of intermediate spectral type (type 1.5-1.9) are highly polarized. None of the nine QSOs classified as type 2 exhibit P>3%.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/409/857
- Title:
- Optical polarization of 3C 279
- Short Name:
- J/A+A/409/857
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a microvariability polarization study in the violently variable quasar 3C 279. We have resolved the polarization curves in the V band for this object down to timescales of minutes. We found two main components in the evolution of the degree of linear polarization, one consisting of a flicker with timescales of several tens of minutes and other component with far more significant variations on timescales of a few days. The linear polarization descended from ~17% down to ~8% in three nights. The polarization angle underwent a sudden change of more that 10 degrees in a few hours, perhaps indicating the injection of a new shock in the jet. The amplitude of the intranight flickering in the degree of polarization is at the level of ~1%. These are probably the best sampled polarization data ever obtained for this object. We also performed IR observations and we provide a follow-up of the evolution of this source at such energies after the main polarization outburst.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/L54
- Title:
- Optical polarization properties of AGNs
- Short Name:
- J/MNRAS/493/L54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Significant positional offsets of the value from 1 mas to more than 10mas were found previously between radio (VLBI) and optical (Gaia) positions of active galactic nuclei (AGNs). They happen preferentially parallel to the parsec-scale jet direction. AGNs with VLBI-to-Gaia offsets pointed downstream the jet are found to have favourably higher optical polarization, as expected if extended optical jets dominate in the emission and shift the Gaia centroid away from the physical nucleus of the source. Upstream offsets with the suggested domination of accretion discs manifest themselves through the observed low optical polarization. Direction of linear optical polarization is confirmed to preferentially align with parsec-scale jets in AGNs with dominant jets consistent with a toroidal magnetic field structure. Our findings support the disc-jet interpretation of the observed positional offsets. These results call on an intensification of AGN optical polarization monitoring programs in order to collect precious observational data. Taken together with the continued VLBI and Gaia observations, they will allow researchers to reconstruct detailed models of the disc-jet system in AGNs on parsec scales.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1119
- Title:
- Optical properties of radio galaxies at z<0.3
- Short Name:
- J/ApJ/723/1119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extended extragalactic radio sources have traditionally been classified into Fanaroff & Riley (FR) I and II types, based on the ratio r_s_ of the separation S between the brightest regions on either sides of the host galaxy and the total size T of the radio source (r_s_~S/T). In this paper, we examine the distribution of various physical properties as a function of r_s_ of 1040 luminous (L>~L*) extended radio galaxies (RGs) at z<0.3 selected with well-defined criteria from the SDSS (Strauss et al. 2002AJ....124.1810S), NVSS (Condon et al. 1998, Cat. VIII/65), and FIRST (Becker et al. 1995+, Cat. VIII/71) surveys. About 2/3 of the RGs are lobe dominated (LD) and 1/3 have prominent jets. If we follow the original definition of the FR types, i.e., a division based solely on r_s_, FRI and FRII RGs overlap in their host galaxy properties.
- ID:
- ivo://CDS.VizieR/J/ApJ/840/97
- Title:
- Optical reverberation mapping campaign of 5 AGNs
- Short Name:
- J/ApJ/840/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-H{beta} lags, we measure black hole masses for all five targets. We also obtain H{gamma} and HeII{lambda}4686 lags for all objects except 3C 382. The HeII{lambda}4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100-300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.
- ID:
- ivo://CDS.VizieR/J/ApJS/145/199
- Title:
- Optical spectroscopic atlas of low-redshift AGN
- Short Name:
- J/ApJS/145/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectral atlas of the H{beta} region for 215 type 1 AGNs (luminous Seyfert 1/radio galaxy nuclei and low-z quasars) up to z~0.8. Line profiles and measures were derived from the database of intermediate resolution spectra (R>~1000) with average continuum level S/N ratio ~30. Parameters including rest frame equivalent width and FWHM are provided for the FeII_opt_ blend at {lambda}4570, H{beta}, HeII {lambda}4686, and the [OIII] {lambda}{lambda}4959, 5007 emission lines. We extract clean broad component H{beta} profiles and provide wavelength measurements at 0, 1/4, 1/2, 3/4, and 0.9 peak intensity levels in order to permit a quantitative definition of the H{beta} broad component for statistical studies. We also discuss sources of uncertainty, selection effects, and biases in our sample. The data are especially important for tests of the eigenvector 1 parameter space occupation and correlation. We show that the I Zw 1 template FeII_opt_ spectrum reproduces well the observed FeII_opt_ emission for a wide range of line width and strength. A detailed analysis of the data within the eigenvector 1 context is deferred to a companion paper.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/48.9
- Title:
- Optical spectroscopic atlas of MOJAVE AGNs
- Short Name:
- J/other/RMxAA/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical spectroscopic atlas for 123 core-dominated radio-loud active galactic nuclei with relativistic jets, drawn from the MOJAVE/2cm (Monitoring of Jets in AGN with VLBA Experiments) sample at 15GHz. It is the first time that spectroscopic and photometric parameters for a large sample of such type of AGN are presented.
- ID:
- ivo://CDS.VizieR/J/ApJS/191/124
- Title:
- Optical spectroscopy of ECDF-S X-ray sources
- Short Name:
- J/ApJS/191/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2Ms area. New spectroscopic redshifts, up to z=4, are measured for 283 counterparts to Chandra sources with deep exposures (t~2-9hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250ks coverage, we provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. Our redshift catalog includes 17 type-2 QSOs at 1<~z<~3.5. Based on our deepest (9 hr) VLT/VIMOS observation, we identify "elusive" optically faint galaxies (Rmag~25) at z~2-3 based upon the detection of interstellar absorption lines (e.g., OII+SiIV, CII], CIV).
- ID:
- ivo://CDS.VizieR/J/A+AS/80/103
- Title:
- Optical spectroscopy of 1Jy, S4 and S5 sources
- Short Name:
- J/A+AS/80/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/748/49
- Title:
- Optical spectroscopy of 1LAC broad-line blazars
- Short Name:
- J/ApJ/748/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on optical spectroscopy of 165 flat spectrum radio quasars (FSRQs) in the Fermi 1LAC sample, which have helped allow a nearly complete study of this population. Fermi FSRQs show significant evidence for non-thermal emission even in the optical; the degree depends on the {gamma}-ray hardness. They also have smaller virial estimates of hole mass than the optical quasar sample. This appears to be largely due to a preferred (axial) view of the {gamma}-ray FSRQ and non-isotropic (H/R ~ 0.4) distribution of broad-line velocities. Even after correction for this bias, the Fermi FSRQs show higher mean Eddington ratios than the optical population. A comparison of optical spectral properties with Owens Valley Radio Observatory radio flare activity shows no strong correlation.
