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571. Optically thick absorbers near luminous quasars
ID:
ivo://CDS.VizieR/J/ApJ/651/61
Title:
Optically thick absorbers near luminous quasars
Short Name:
J/ApJ/651/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
With close pairs of quasars at different redshifts, a background quasar sight line can be used to study a foreground quasar's environment in absorption. We search 149 moderate-resolution background quasar spectra from Gemini, Keck, the MMT, and the SDSS to survey Lyman limit systems (LLSs) and damped Ly{alpha} systems (DLAs) in the vicinity of 1.8<z<4.0 luminous foreground quasars. A sample of 27 new quasar-absorber pairs is uncovered with column densities 10^17.2^cm^-2^<NH<10^20.9^cm^-2^ and transverse (proper) distances of 22h^-1^kpc<R<1.7h^-1^Mpc from the foreground quasars.
572. Optically thin CIII absorbers at z~2.5
ID:
ivo://CDS.VizieR/J/MNRAS/456/3509
Title:
Optically thin CIII absorbers at z~2.5
Short Name:
J/MNRAS/456/3509
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Voigt profile analysis of 132 intervening CIV+CIII components associated with optically thin HI absorbers at 2.1<z<3.4 in the 19 high-quality UVES/VLT and HIRES/Keck QSO spectra. For logN_CIV_ in [11.7, 14.1], N_CIII_{propto}N_CIV_^1.42+/-0.11^ and <N_CIII}/N_CIV>=1.0+/-0.3 with a negligible redshift evolution. For 54 CIV components tied (aligned) with HI at logN_HI_ in [12.2, 16.0] and logN_CIV_ in [11.8, 13.8], the gas temperature T_b_ estimated from absorption line widths is well approximated to a Gaussian peaking at logT_b_~4.4+/-0.3 for logT_b_ in [3.5, 5.5], with a negligible non-thermal contribution. For 32 of 54 tied HI+CIV pairs, also tied with CIII at logN_CIII_ in [11.7, 13.8], we ran both photoionization equilibrium (PIE) and non-PIE (using a fixed temperature T_b_) cloudy models for the Haardt-Madau QSOs+galaxies 2012 UV background. We find evidence of bimodality in observed and derived physical properties. High-metallicity branch absorbers have a carbon abundance [C/H]temp>=-1.0, a line-of-sight length L_temp_<=20kpc and a total (neutral and ionized) hydrogen volume density logn_H,temp_ in [-4.5, -3.3] and logT_b_ in [3.9, 4.5]. Low-metallicity branch absorbers have [C/H]temp<=-1.0, L_temp_ in [20, 480]kpc and logn_H,temp_ in [-5.2, -4.3] and logT_b_~ 4.5. High-metallicity branch absorbers seem to be originated from extended discs, inner haloes or outflowing gas of intervening galaxies, while low-metallicity absorbers are produced by galactic haloes or the surrounding intergalactic medium filament.
573. Optical microvariability in radio-quiet quasars
ID:
ivo://CDS.VizieR/J/AJ/133/303
Title:
Optical microvariability in radio-quiet quasars
Short Name:
J/AJ/133/303
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a study of optical microvariability in radio-quiet and radio-intermediate quasars. Observations were obtained on a total of seven objects: five radio-quiet quasars and two radio-intermediate quasars. No microvariability was detected in either the radio-quiet or radio-intermediate objects in our sample, despite intensive monitoring for several consecutive nights. In one object, PG 1257+346, evidence for interday variability was detected. We examined a sample of 117 radio-quiet objects found in the literature that have been studied for microvariability. This sample is discussed in terms of classification, redshift distribution, R (the ratio of the radio [5GHz] flux to the optical [4400{AA}] flux), optical magnitude, luminosity, and observing strategy.
574. Optical monitoring of extragalactic sources
ID:
ivo://CDS.VizieR/J/A+A/552/A98
Title:
Optical monitoring of extragalactic sources
Short Name:
J/A+A/552/A98
Date:
21 Oct 2021
Publisher:
CDS
Description:
The goal to this work is to observe a first set of 70 extragalactic sources at optical wavelengths that could achieve the link with the ICRF. Variations in the light curves of these targets are connected with astrophysical processes that could produce displacements of the optical photocenter. Such displacements, if they exist, are critical in the framework of the link of reference systems. Four telescope were used to observe the targets at optical wavelengths. Two of them are located in France, one in Chile, and the last in Australia. First observations were carried out during one year and a half in the R and V bands. A new method of characterizing the compactness of the targets was applied to the images obtained.
575. Optical monitoring of gamma-ray loud blazars. I
ID:
ivo://CDS.VizieR/J/A+AS/121/119
Title:
Optical monitoring of gamma-ray loud blazars. I
Short Name:
J/A+AS/121/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of the optical monitoring between November 1994 and November 1995 of twenty gamma-ray loud blazars included in the Torino blazar monitoring program are presented.
576. Optical Monitoring of Quasar 3C345
ID:
ivo://CDS.VizieR/J/AZh/72/447
Title:
Optical Monitoring of Quasar 3C345
Short Name:
J/AZh/72/447
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results of long-term monitoring of the quasar 3C345 from 1984 to 1991 are presented. Observations has been conducted on the Byurakanskii station of the St. Petersburg Astronomical Institute since 1968 in the B band, and consist of 365 brightness estimates obtained over the course of 219 nights.
577. Optical monitoring of SDSS J1004+4112
ID:
ivo://CDS.VizieR/J/ApJ/662/62
Title:
Optical monitoring of SDSS J1004+4112
Short Name:
J/ApJ/662/62
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 426 epochs of optical monitoring data spanning 1000 days from 2003 December to 2006 June for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is {Delta}t_BA_=38.4+/-2.0days ({Delta}{chi}^2^=4) in the expected sense that B leads A and the overall time ordering is C-B-A-D-E. The measured delay invalidates all published models. The models probably failed because they neglected the perturbations from cluster member galaxies. Models including the galaxies can fit the data well, but conclusions about the cluster mass distribution should await the measurement of the longer, and less substructure sensitive, delays of the C and D images. For these images, a delay of {Delta}t_CB_~=681+/-15days is plausible but requires confirmation, while delays of {delta}t_CB_>560days and {delta}t_AD_>800 days are required. We clearly detect microlensing of the A/B images, with the delay-corrected flux ratios changing from mB-mA=0.44+/-0.01mag in the first season to 0.29+/-0.01mag in the second season and 0.32+/-0.01mag in the third season.
578. Optical observations of GPS radio sources
ID:
ivo://CDS.VizieR/J/A+A/463/97
Title:
Optical observations of GPS radio sources
Short Name:
J/A+A/463/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify optical counterparts, address uncertain identifications and measure previously unknown redshifts of the host galaxies of candidate Gigahertz Peaked Spectrum (GPS) radio sources, and study their stellar populations. Long slit spectroscopy and deep optical imaging in the B, V and R bands, were obtained with the Very Large Telescope.
579. Optical outbursts of the blazar 3C 345
ID:
ivo://CDS.VizieR/J/PAZh/25/893
Title:
Optical outbursts of the blazar 3C 345
Short Name:
J/PAZh/25/893
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photographic UBV photometry of the blazar 3C 345 that were made during 79 nights in 1971-1974 and 1983-1984 as a part of the Petersburg Quasar Monitoring Program (PQMP) carried out at the Astronomical Institute of the St.-Petersburg University. These data were previously published by piecemeal (references are presented in Section 4). Now after partial revision these data are united in Table 1 that presents nightly averaged UBV magnitudes together with its rms errors (see Section 4 of the paper for the details). These data were used for the comparison of the spectral indices of the emission in the "fast" (time scales of nearly 10-20 days) and "slow" (time scales of nearly 1 yeas) outbursts in 3C 345.
580. Optical photometry for 1ES 1959+650
ID:
ivo://CDS.VizieR/J/AJ/150/67
Title:
Optical photometry for 1ES 1959+650
Short Name:
J/AJ/150/67
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the 1.56m telescope at Shanghai Observatory, China, we present the photometric results of 1ES 1959+650, which cover from 2006 June 11 to 2014 July 31. The maximum variabilities are {Delta}m_V|max_=1.74+/-0.02mag in the V band, {Delta}m_R|max_=0.97+/-0.02mag in the R band, and {Delta}m_I/max_=1.15+/-0.03mag in the I band. During the monitoring period, we obtain intraday variabilities on 2009 September 2 (JD2455077) and 2009 September 3 (JD2455078). On 2009 September 2, the intraday variabilities are {Delta}m_V_=0.36+/-0.08mag within 1.56hr, {Delta}m_R_=0.21+/-0.04mag within 23minutes, and {Delta}m_I_=0.53+/-0.03mag within 45minutes. On 2009 September 3, the intraday variabilities are {Delta}m_V_=0.40+/-0.10mag within 27minutes, {Delta}m_R_=0.48+/-0.04mag within 3.24hr, and {Delta}m_I_=0.68+/-0.06mag within 3.72hr. The two intraday variabilities occur in 24hr, which may occur in the same variable phase. Other results show that (1) no quasi-periodicity is found in the long-term light curve and (2) the correlations between the brightness and the spectrum show obvious anti-correlation, {alpha}=-(0.18+/-0.02)F_V_+(2.33+/-0.12), with the correlation coefficient r=-0.74 and the chance probability p<0.01%.