- ID:
- ivo://CDS.VizieR/J/MNRAS/439/1556
- Title:
- ACT high significance 148 and 218GHz sources
- Short Name:
- J/MNRAS/439/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 and/or 218GHz in the 2008 Southern survey. Flux densities span 14 -1700mJy, and we use source spectral indices derived using ACT-only data to divide our sources into two subpopulations: 167 radio galaxies powered by central active galactic nuclei (AGN) and 24 dusty star-forming galaxies (DSFGs). We cross-identify 97 percent of our sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogues. When combined with flux densities from the Australia Telescope 20GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spectral energy distribution from 20 to 148GHz, with the trend continuing to 218GHz. The ACT dust-dominated source population has a median spectral index, {alpha}_148-218_, of 3.7^+0.62^_-0.86_, and includes both local galaxies and sources with redshift around 6. Dusty sources with no counterpart in existing catalogues likely belong to a recently discovered subpopulation of DSFGs lensed by foreground galaxies or galaxy groups.
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- ID:
- ivo://CDS.VizieR/J/ApJ/850/207
- Title:
- Action dynamics of the Local Supercluster
- Short Name:
- J/ApJ/850/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fully nonlinear gravitationally induced trajectories of a nearly complete set of galaxies, groups, and clusters in the Local Supercluster are constructed in a numerical action method model constrained by data from the CosmicFlows survey and various distance indicators. We add the gravity field due to inhomogeneities external to the sample sphere by making use of larger-scale peculiar flow measurements. Assignments of total masses were made to find the best overall set of mutual attractions, as determined by a goodness criterion based on present-day radial velocities, individually for the Virgo Cluster, M31, and the Milky Way (MW), and via a mass-to-light ratio relationship for other masses. The low median chi-square found indicates that the model fits the present-day velocity flow well, but a slightly high mean chi-square may indicate that some masses underwent complex orbits. The best fit, when setting the value of H_0_ to the CosmicFlows value of 75km/s/Mpc and the WMAP value for {Omega}_m_=0.244 consistent with that H_0_, occurs with the following parameters: {Omega}_orphan_=0.077+/-0.016, M/L_K_=40+/-2L_10_^0.15^M_{sun}_/L_{sun}_ (L_10_ is the K-band luminosity in units of 10^10^L_{sun}_), a Virgo mass of 6.3+/-0.8x10^14^M_{sun}_ (M/L_K_=113+/-15M_{sun}_/L_{sun}_), and a mass for the MW plus M31 of 5.15+/-0.35x10^12^M_{sun}_. The best constant mass-to-light ratio is M/L_K_=58+/-3M_{sun}_/L_{sun}_. The Virgocentric turnaround radius is 7.3+/-0.3Mpc. We explain several interesting trends in peculiar motions for various regions now that we can construct the 3D orbital histories.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/369
- Title:
- 10 active binary radial velocities
- Short Name:
- J/A+AS/137/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital elements have been determined for 10 chromospherically active binaries from a combination of new velocities and velocities in the literature. First orbits for three binaries, HD 33363, HD 152178, and HD 208472, are presented, as well as updated orbits for seven other binaries. Two of the latter systems, LN Peg and HD 106225 were discovered to be triple, and both short- and long-period orbits have been computed for each. Fundamental properties have been determined for the chromospherically active primary in each system.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A122
- Title:
- Active deep learning in large spectros. surveys
- Short Name:
- J/A+A/643/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Current archives of the LAMOST telescope contain millions of pipeline-processed spectra that have probably never been seen by human eyes. Most of the rare objects with interesting physical properties, however, can only be identified by visual analysis of their characteristic spectral features. A proper combination of interactive visualisation with modern machine learning techniques opens new ways to discover such objects. We apply active learning classification methods supported by deep convolutional neural networks to automatically identify complex emission-line shapes in multi-million spectra archives. We used the pool-based uncertainty sampling active learning method driven by a custom-designed deep convolutional neural network with 12 layers. The architecture of the network was inspired by VGGNet, AlexNet, and ZFNet, but it was adapted for operating on one-dimensional feature vectors. The unlabelled pool set is represented by 4.1 million spectra from the LAMOST data release 2 survey. The initial training of the network was performed on a labelled set of about 13000 spectra obtained in the 400{AA} wide region around H{alpha} by the 2m Perek telescope of the Ondrejov observatory, which mostly contains spectra of Be and related early-type stars. The differences between the Ondrejov intermediate-resolution and the LAMOST low-resolution spectrographs were compensated for by Gaussian blurring and wavelength conversion. After several iterations, the network was able to successfully identify emission-line stars with an error smaller than 6.5%. Using the technology of the Virtual Observatory to visualise the results, we discovered 1013 spectra of 948 new candidates of emission-line objects in addition to 664 spectra of 549 objects that are listed in SIMBAD and 2644 spectra of 2291 objects identified in an earlier paper of a Chinese group led by Wen Hou. The most interesting objects with unusual spectral properties are discussed in detail.
- ID:
- ivo://CDS.VizieR/J/AJ/87/739
- Title:
- Active extragalactic objects I.
- Short Name:
- J/AJ/87/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As one part of a program to detect complete samples of active extragalactic objects, the 3.36x10^-3^sr field centered on alpha=12h04min, delta=+11deg30' (1950.0) was mapped with the Very Large Array at 1411MHz. Sixty-seven maps cover this field so that no point is more than 15arcmin from the nearest map center. The median map noise is 0.6mJy, and the 6sigma completeness limit is less than 6mJy over half of the survey field. The synthesized point-source response is an elliptical Gaussian 22x18arcsec between half-intensity points. The rms source-position uncertainties are ~1arcsec in each coordinate so that reliable optical identifications can be made on the basis of radio-optical position coincidence alone. The sky density of sources with flux densities 5<=S<150mJy and the angular-size distribution of sources between 30 and 150mJy were determined.
- ID:
- ivo://CDS.VizieR/J/AJ/87/1429
- Title:
- Active extragalactic objects II.
- Short Name:
- J/AJ/87/1429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A single primary-beam area centered on alpha=08h52m16s, Delta=+17d16' (1950.0) was surveyed with the Very Large Array at 1.452 GHz. The rms map noise is 0.030 + 0.001 mJy, and the resulting source list is complete to a map peak flux density S_p = 0.2 mJy within 25 arcmin of the field center. Source counts between 0.2 and 5 mJy were determined. Our best-fit model for the counts suggests that the faintest sources have absolute radio luminosities L < 10^24 W/Hz and do not evolve significantly. Sources stronger than 0.2 mJy appear to account for most of the radio-source background. The rms sky-temperature fluctuation in the central 10'x10' of the map is less than 0.029 K (>99% confidence) on an angular scale ~19 arcsec. This limit constrains theories which attribute the cosmic microwave background to thermalized radiation from massive pregalactic stars or bursts of star formation in young galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/90/1437
- Title:
- Active Extragalactic Objects III
- Short Name:
- J/AJ/90/1437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Three selected fields were observed with the Very Large Array (VLA) at 1411MHz as part of an ongoing project to compile complete samples of active extragalactic objects. The radio-source list for the field "A" centered on alpha=08h54m, delta=+17d30' is presented. 67 maps cover the area 3x3deg so that every point lies within at least one primary half-power beamwidth. The median map noise is 0.5mJy and the 6{sigma} completeness level is less than 6mJy over half the field. The synthesized point-source response is an elliptical Gaussian approximately 20x17" between half-intensity points. The areal density of sources with flux densities in the range 5<S<150mJy was determined. Optical identifications based on position coincidences with 90 objects brighter than B=~21.5 in the A and B survey fields are reported.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2879
- Title:
- Active galactic nuclei from HeII
- Short Name:
- J/MNRAS/466/2879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the HeII {lambda}4685 emission line diagnostic diagram by Shirazi & Brinchmann (2012, Cat. J/MNRAS/421/1043) in addition to the standard methods based on other optical emission lines. The HeII-based diagnostics is more sensitive to AGN ionization in the presence of strong star formation than conventional line diagnostics. We survey a magnitude-limited sample of 63915 galaxies from the Sloan Digital Sky Survey Data Release 7 at 0.02<z<0.05 and use both the conventional BPT emission line diagnostic diagrams, as well as the HeII diagram to identify AGN. In this sample, 1075 galaxies are selected as AGN using the BPT diagram, while additional 234 galaxies are identified as AGN using the HeII diagnostic diagram, representing a 22 per cent increase of AGN in the parent galaxy sample. We explore the host galaxy properties of these new HeII-selected AGN candidates and find that they are most common in star-forming galaxies on the blue cloud and on the main sequence where ionization from star formation is most likely to mask AGN emission in the BPT lines. We note in particular a high He II AGN fraction in galaxies above the high-mass end of the main sequence where quenching is expected to occur. We use archival Chandra observations to confirm the AGN nature of candidates selected through He II-based diagnostic. Finally, we discuss how this technique can help inform galaxy/black hole coevolution scenarios.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A65
- Title:
- Active Kepler stars differential rotation
- Short Name:
- J/A+A/583/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In addition to the discovery of hundreds of exoplanets, the high-precision photometry from the CoRoT and Kepler satellites has led to measurements of surface rotation periods for tens of thousands of stars, which can potentially be used to infer stellar ages via gyrochronology. Our main goal is to derive ages of thousands of field stars using consistent rotation period measurements derived by different methods. Multiple rotation periods are interpreted as surface differential rotation (DR). We study the dependence of DR with rotation period and effective temperature. We reanalyze a previously studied sample of 24,124 Kepler stars using different approaches based on the Lomb- Scargle periodogram. Each quarter (Q1-Q14) is treated individually using a prewhitening approach. Additionally, the full time series and their different segments are analyzed.
- ID:
- ivo://CDS.VizieR/J/AZh/79/963
- Title:
- Active radio galaxies in cluster A569
- Short Name:
- J/AZh/79/963
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nature of bright radio sources with known radio spectra in the direction of the nearby cluster of galaxies A569 (z=0.0193) is investigated. The optical identifications of the sources were provided. 45% of these radio sources are associated with compact galaxies. A substantial fraction of these galaxies have active nuclei. Some of them have radio halos.
