- ID:
- ivo://CDS.VizieR/J/ApJ/549/155
- Title:
- [OIII] emission in a sample of AGNs
- Short Name:
- J/ApJ/549/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The emission-line flux ratio of [OIII]4363/[OIII]5007 (R_OIII_) is a useful diagnostic for the ionization mechanism and physical properties of emission-line regions in active galactic nuclei (AGNs). However, it is known that simple photoionization models underpredict the [OIII]4363 intensity, being inconsistent with observations. In this paper we report on several pieces of evidence that a large fraction of the [OIII]4363 emission arises from the dense gas obscured by putative tori: (1) the visibility of high-R_OIII_ regions is correlated to that of broad-line regions, (2) higher R_OIII_ objects show hotter mid-infrared colors, (3) higher R_OIII_ objects show stronger highly ionized emission lines such as [FeVII] 6087 and [FeX]6374, and (4) higher R_OIII_ objects have broader line width of [OIII]4363 normalized by that of [OIII]5007.
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- ID:
- ivo://CDS.VizieR/J/ApJ/883/94
- Title:
- Optical and UV follow-up of 1ES 1927+654
- Short Name:
- J/ApJ/883/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the sudden optical and ultraviolet (UV) brightening of 1ES1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of "true Type-2" AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., CIV{lambda}1549, CIII]{lambda}1909, MgII{lambda}2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a "changing look" AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.
- ID:
- ivo://CDS.VizieR/J/A+A/310/384
- Title:
- Optical brightness of 3 ROSAT Seyfert galaxies
- Short Name:
- J/A+A/310/384
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The printed version of this paper describes the X-ray and optical properties of four new active galaxies discovered in the ROSAT All-Sky Survey. While one object (RX J1257.5+2412) is identified as a BL Lac object, the other three (RX J1239.3+2431, RX J1225.7+2055, and RX J1250.2+1923) are narrow line Seyfert 1 galaxies. Three of these four objects are bright enough to be studied on archival photographic plates of Sonneberg Observatory. The present list contains the individual brightness measurements of these objects all of which turned out to be variable on timescales of weeks to years. Some lightcurves (long-term as well as short-term) are given in the printed version.
- ID:
- ivo://CDS.VizieR/J/ApJ/641/140
- Title:
- Optical counterparts in the NDWFS Bootes field
- Short Name:
- J/ApJ/641/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XBootes Survey is a 5ks Chandra survey of the Bootes Field of the NOAO Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest (9.3{deg}^2^) contiguous region imaged in X-ray with complementary deep optical and near-infrared (near-IR) observations. We present a catalog of the optical counterparts to the 3213 X-ray point sources detected in the XBootes survey. Using a Bayesian identification scheme, we successfully identified optical counterparts for 98% of the X-ray point sources.
- ID:
- ivo://CDS.VizieR/VII/178
- Title:
- Optical Extragalactic Emission-line Objects
- Short Name:
- VII/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of 935 galaxies which have optical properties similar to those of QSOs is given. A subsidiary table of cross-identifications enables the reader to relate the name of a given object to its coordinate name. Most of the objects appear to be nonstellar. The majority, more than 700, have redshifts z<=0.2, and have mostly been classified as Seyfert galaxies, N systems, or radio galaxies. The Hubble diagram for all of the objects with z<=0.2 is shown. The redshift distribution peaks at z ~ 0.025, but there are about 200 powerful radio galaxies in the extended tail of the distribution which have z>0.2. There is a separate and distinct peak in the redshift distribution at z=0.06.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/32
- Title:
- Optical/{gamma}-ray flares for Fermi-LAT blazars
- Short Name:
- J/ApJ/880/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Even with several thousand Fermi-Large Area Telescope (LAT) blazar detections, the {gamma}-ray emission mechanism is poorly understood. We explore correlated optical/{gamma}-ray flux variations for 178 Fermi-LAT blazars regularly monitored by the Katzman Automatic Imaging Telescope, the Small and Moderate Aperture Research Telescope System, and the Steward Observatory. Out of the 178 sources, 121 show a measurable (>1{sigma}) discrete correlation function peak. Using the derived time lags and Bayesian block light-curve decompositions, we measure the fraction of common and orphan flares between the two bands. After accounting for sampling and sensitivity limitations we quantify for the first time the true orphan flare rates of optical and {gamma}-ray flares: 54.5% of optical and 20% of {gamma}-ray flares are orphan events. Both the intraband temporal relation and the small orphan {gamma}-ray flare fraction point toward leptonic processes as the likely mechanisms for the high-energy emission. Motivated to discriminate between synchrotron self-Compton (SSC) and external-Compton dominance in individual sources, we use the flux-flux variations to determine the slope m of the log fopt-log f{gamma} dependence. The slope distribution suggests a bimodal population with high and intermediate synchrotron peak objects showing larger m than low synchrotron peak objects. We find that m is naturally decreased through pollution from the orphan (typically optical) flares and develop a method to statistically recover, given the sources' measured orphan flare rate, the intrinsic m. While source classes show composite behavior, the majority of BL Lac objects favor m=2, indicating an SSC origin for the {gamma}-rays. No preference for either m is found in flat spectrum radio quasars.
- ID:
- ivo://CDS.VizieR/J/other/PABei/30.106
- Title:
- Optical identification of ROSAT AGN
- Short Name:
- J/other/PABei/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The completeness of sample is especially important for the research of quasar and using data in one wavelength, such as in radio, infrared, optical or X-ray selection, to make candidate selection always suffers significant selection effect to some extent. Fortunately, some large area surveys have become increasingly prevalent across all wavelengths over the past decade, such as SDSS, NVSS, FIRST, RASS, etc. These surveys make it possible to select candidates in multiple wavelengths and the resulting sample is more complete.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/1
- Title:
- Optical identification of S5 catalog
- Short Name:
- J/A+AS/115/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications, magnitudes, and redshifts have been compiled for the 185 radio sources of the S5 catalogue, representing its current optical identification status. Reliable optical counterparts are found for more than 75% of the sources, nearly 50% of which have measured redshifts. Our tabulation also includes radio positions, radio fluxes, and radio spectral indices. References to other catalogues and detailed supplementary notes are given for a large fraction of the sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/11
- Title:
- Optical identifications of radio sources
- Short Name:
- J/A+AS/115/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD images of the fields of 115 radio sources from the 1Jy, S4 and S5 catalogues are presented. New optical counterparts have been found for a total of 34 sources, a large fraction of which had as yet only been described as empty fields on Sky Survey Plates. Of the 54 radio sources with previously published identifications, 50 optical counterparts have been confirmed while for 4 sources new identifications are proposed. R band magnitudes, derived from the CCD images, are provided for all but a few identified optical counterparts. The fields at the positions of 27 radio sources are still empty down to a limiting magnitude of at least m_R_=22mag, requiring much deeper optical as well as additional infrared images for establishing their optical counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/26
- Title:
- Optical light curves of PHL1811 and 3C273
- Short Name:
- J/ApJS/213/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability is one of the most observable characteristics of active galactic nuclei, and it is important when considering the emission mechanism. In this paper, we report optical photometry monitoring of two nearby brightest quasars, PHL 1811 and 3C 273, using the ST-6 camera attached to the Newtonian focus and the Ap6E CCD camera attached to the primary focus of the 70cm meniscus telescope at the Abastumani Observatory, Georgia. PHL 1811 was monitored during the period from 2002 September to 2012 December, while 3C 273 was monitored during the period from 1998 February to 2008 May. During our monitoring period, the two sources did not show any significant intra-day variability. The largest detected variations are {Delta}R=0.112+/-0.010mag. for PHL 1811, {Delta}B=0.595+/-0.099mag, {Delta}V=0.369+/-0.028mag, {Delta}R=0.495+/-0.076mag, and {Delta}I=0.355+/-0.009mag for 3C 273. When the periodicity analysis methods are adopted for the observations of the sources, a period of p=5.80+/-1.12yr is obtained for PHL 1811 in the R light curve in the present work, and periods of p=21.10+/-0.14, 10.00+/-0.14, 7.30+/-0.09, 13.20+/-0.09, 2.10+/-0.06, and 0.68+/-0.05yr are obtained for 3C 273 based on the data in the present work combined with historical works.
