- ID:
- ivo://CDS.VizieR/J/A+A/365/409
- Title:
- ISO continuum observations of quasars
- Short Name:
- J/A+A/365/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eight luminous quasars with -30<M_B_<-27 at z=1.4-3.7 have been observed in the mid- and far-infrared using ISO. All the quasars have been detected in the mid-infrared bands of ISOCAM, while no far-infrared detections have been made with ISOPHOT. SEDs (Spectral Energy Distributions) from the UV to far-infrared have been obtained while supplementing ISO observations with photometry in the optical and near-infrared made from the ground within 17 months. The SEDs are compared with the MED (Mean spectral Energy Distributions) of low-redshift quasars with -27<M_B_<-22. It is shown that our far-infrared observations were limited by confusion noise due to crowded sources.
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- ID:
- ivo://CDS.VizieR/J/A+A/298/375
- Title:
- Jet-disk symbiosis II
- Short Name:
- J/A+A/298/375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the correlation between the accretion disk (UV) luminosity and the radio core emission of a quasar sample, containing all PG quasars, also deriving empirical conversion factors from emission line luminosities to disk luminosities. This method allows us to investigate the radio properties of AGN on the absolute scale set by the accretion power. The tables contain the quasar (and radio galaxy) sample discussed in this paper (including the complete PG quasars sample) and give the derived `disk luminosities' of the UV-bump and 5GHz radio luminosities.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A26
- Title:
- Jet models for the quasar NRAO150
- Short Name:
- J/A+A/566/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the study of the relativistic jet of the quasar NRAO150. Our study confirm that the jet is seen at an extremely small angle to the line of sight and there is not a clear region to be identify as the core of the jet. The innermost regions of the jet show a counter-clockwise jet position angle swing at a high angular rate. We have studied the kinematic of the emission features into the innermost regions by fitting a model which explain the jet position angle swing as a rotation of the jet material following the toroidal magnetic field. This could be the first direct evidences about the helical structure of the magnetic field into the innermost regions of relativistic jets.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/97
- Title:
- Jet power of blazars from the TGSS at 150MHz
- Short Name:
- J/ApJ/861/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The composition and energy dissipation in jets are two of the fundamental questions of jet physics that are not fully understood. In this paper, we attempt to constrain the composition, magnetization, and radiative efficiency for blazars with the recently released low-frequency radio catalog of the TIFR GMRT Sky Survey at 150MHz. The jet power estimated from the low-frequency radio emission is much lower than that derived from spectral energy distribution fitting assuming one proton per electron. Assuming the jet power estimated from low-frequency radio emission is physical, the fraction of electron/positron pairs can be constrained with n_pairs_/n_p_~10. By comparing the power carried by the magnetic field and radiation with the jet power estimated from the low-frequency radio emission, we find both the relatively high magnetization parameter of {sigma}~0.5 and the radiative efficiency of {eta}~0.4 in the dissipation region of blazars. These results suggest that magnetic reconnection processes may play an important role in the energy dissipation of blazars. We also explore the connection between these three parameters (n_pairs_/n_p_, {sigma}, and {eta}) and the black hole mass, disk luminosity, and Eddington ratio. No significant correlation is found, except that {sigma} shows a possible correlation with disk luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/23
- Title:
- JHK' imaging photometry of Seyfert 1. I.
- Short Name:
- J/ApJS/141/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared JHK' imaging photometry was obtained of 331 AGNs consisting mainly of Seyfert 1 active galactic nuclei (AGNs) and quasars (QSOs). This sample was selected to cover a range of radio emission strength, redshift from z=0 to 1, and absolute B magnitude from M_B_=-29mag to -18mag. Among low-z AGNs with z<0.3, Seyfert 1-1.5 AGNs are distributed over a region from a location typical of "galaxies" to a location typical of "QSOs" in the two-color J-H to H-K' diagram, but Seyfert 1.8-2 AGNs are distributed around the location of "galaxies". Moreover, bright AGNs with respect to absolute B magnitude are distributed near the location of "QSOs," while faint AGNs are near the location of "galaxies". The distribution of such low-z AGNs in this diagram was found to have little dependence on their 6 cm radio flux. The near-infrared colors of the AGNs observed with an aperture of 7 pixels (7.49") are more QSO-like than those observed with larger apertures up to 15 pixels (16.1"). This aperture effect may be explained by contamination from the light of host galaxies within larger apertures. This effect is more prominent for less luminous AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/31
- Title:
- JHK' imaging photometry of Seyfert 1. II.
- Short Name:
- J/ApJS/141/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of 226 AGNs in the near-infrared J, H, and K' bands are presented along with the analysis of the observations for variability. Our sample consists mainly of Seyfert 1 AGNs and QSOs. About a quarter of the objects in each category are radio loud. The AGNs in the entire sample have the redshifts spanning the range from z=0 to 1, and the absolute magnitudes from M_B_=-29 to -18. All the objects were observed twice, and their variability was measured by differential photometry. A reduction method of differential photometry, optimized to the analysis of extended images, has been developed. The systematic error in variability arising from AGNs of highly extended images is estimated to be less than 0.01mag in each of the J, H, and K' bands. The systematic error arising from the flat-fielding is negligible for most AGNs, although it is more than 0.1mag for some particular cases. The overall average flat-fielding error is 0.03mag for the image pairs. We find that these systematic errors are superseded by statistical errors, and the overall average total systematic and statistical errors amounts to 0.05mag in the measured variability in each band.
- ID:
- ivo://CDS.VizieR/J/A+AS/135/83
- Title:
- JK'R magnitude of QSOs and around them
- Short Name:
- J/A+AS/135/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed a sample of 15 and 8 quasars with redshifts between 0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively. Eleven of the quasars were previously known to be associated with extended emission line regions. After deconvolution of the image, substraction of the PSF when possible, and identification of companions with the help of HST archive images when available, extensions are seen for at least eleven quasars. However, average profiles are different from that of the PSF in only four objects, for which a good fit is obtained with an r^1/4^ law, suggesting that the underlying galaxies are ellipticals. Redshifts were available in the literature for surrounding objects in five quasar fields. For these objects, one to five companion galaxies were found. One quasar even belongs to a richness class 1 cluster. Most other quasars in our sample have nearby galaxies in projection which may also be companions. Environmental effects are therefore probably important to account for the properties of these objects.
- ID:
- ivo://CDS.VizieR/J/A+A/596/A106
- Title:
- 1Jy northern AGN sample
- Short Name:
- J/A+A/596/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.
- ID:
- ivo://CDS.VizieR/J/AJ/140/390
- Title:
- Karhunen-Loeve transform of SDSS QSOs
- Short Name:
- J/AJ/140/390
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Karhunen-Loeve (KL) transform can compactly represent the information contained in large, complex datasets, cleanly eliminating noise from the data and identifying elements of the dataset with extreme or inconsistent characteristics. We develop techniques to apply the KL transform to the 4000-5700{AA} region of 9800 QSO spectra with z<0.619 from the SDSS archive. Up to 200 eigenspectra are needed to fully reconstruct the spectra in this sample to the limit of their signal-to-noise (S/N). We propose a simple formula for selecting the optimum number of eigenspectra to use to reconstruct any given spectrum, based on the S/N of the spectrum, but validated by formal cross-validation tests.
- ID:
- ivo://CDS.VizieR/J/ApJ/657/409
- Title:
- K-band light curve of GRS 1915+105
- Short Name:
- J/ApJ/657/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of 7 years of K-band monitoring of the low-mass X-ray binary GRS 1915+105. Positive correlations between the infrared flux and the X-ray flux and X-ray hardness are demonstrated. Analysis of the frequency spectrum shows that the orbital period of the system is P_orb_=30.8+/-0.2days. The phase and amplitude of the orbital modulation suggests that the modulation is due to the heating of the face of the secondary star. We also report another periodic signature between 31.2 and 31.6days, most likely due to a superhump resonance. From the superhump period we then obtain a range for the mass ratio of the system, 0.05<q<0.12.
