- ID:
- ivo://CDS.VizieR/J/ApJ/889/49
- Title:
- The ELM Survey. VIII. Final double WD binaries
- Short Name:
- J/ApJ/889/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final sample of 98 detached double white dwarf (WD) binaries found in the Extremely Low Mass (ELM) Survey, a spectroscopic survey targeting <0.3M_{sun}_ He-core WDs completed in the Sloan Digital Sky Survey footprint. Over the course of the survey we observed ancillary low-mass WD candidates like GD 278, which we show is a P=0.19d double WD binary, as well as candidates that turn out to be field blue straggler/subdwarf A-type stars with luminosities too high to be WDs given their Gaia parallaxes. Here, we define a clean sample of ELM WDs that is complete within our target selection and magnitude range 15<g_0_<20mag. The measurements are consistent with 100% of ELM WDs being 0.0089<P<1.5d double WD binaries, 35% of which belong to the Galactic halo. We infer that these are mostly He+CO WD binaries given the measurement constraints. The merger rate of the observed He+CO WD binaries exceeds the formation rate of stable mass-transfer AM CVn binaries by a factor of 25, and so the majority of He+CO WD binaries must experience unstable mass transfer and merge. The systems with the shortest periods, such as J0651+2844, are signature LISA verification binaries that can be studied with gravitational waves and light.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/818/155
- Title:
- The ELM survey. VII. 15 new ELM white dwarf cand.
- Short Name:
- J/ApJ/818/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 15 extremely low-mass (5<logg<7) white dwarf (WD) candidates, 9 of which are in ultra-compact double-degenerate binaries. Our targeted extremely low-mass Survey sample now includes 76 binaries. The sample has a lognormal distribution of orbital periods with a median period of 5.4hr. The velocity amplitudes imply that the binary companions have a normal distribution of mass with 0.76 M_{sun}_ mean and 0.25M_{sun}_ dispersion. Thus extremely low-mass WDs are found in binaries with a typical mass ratio of 1:4. Statistically speaking, 95% of the WD binaries have a total mass below the Chandrasekhar mass, and thus are not type Ia supernova progenitors. Yet half of the observed binaries will merge in less than 6Gyr due to gravitational wave radiation; probable outcomes include single massive WDs and stable mass transfer AM CVn binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/167
- Title:
- The ELM survey. VI. 11 new ELM WD binaries
- Short Name:
- J/ApJ/812/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 11 new double degenerate systems containing extremely low-mass white dwarfs (ELM WDs). Our radial velocity observations confirm that all of the targets have orbital periods <=1 day. We perform spectroscopic fits and provide a complete set of physical and binary parameters. We review and compare recent evolutionary calculations and estimate that the systematic uncertainty in our mass determinations due to differences in the evolutionary models is small (~0.01M_{sun}_). Five of the new systems will merge due to gravitational wave radiation within a Hubble time, bringing the total number of merger systems found in the ELM Survey to 38. We examine the ensemble properties of the current sample of ELM WD binaries, including the period distribution as a function of effective temperature, and the implications for the future evolution of these systems. We also revisit the empirical boundaries of instability strip of ELM WDs and identify new pulsating ELM WD candidates. Finally, we consider the kinematic properties of our sample of ELM WDs and estimate that a significant fraction of the WDs from the ELM Survey are members of the Galactic halo.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/66
- Title:
- The ELM survey. V. White dwarf binaries
- Short Name:
- J/ApJ/769/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P<=1 day) binaries. Our sample includes four objects with remarkable logg=~5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times <10Gyr. Four have >~0.9M_{sun}_ companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the Extremely low mass (ELM) Survey to 54; 31 of these binaries will merge within a Hubble time.
- ID:
- ivo://CDS.VizieR/J/ApJ/863/144
- Title:
- The ELQS in SDSS footprint. II. North Gal. Cap
- Short Name:
- J/ApJ/863/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the North Galactic Cap sample of the Extremely Luminous Quasar Survey (ELQS-N), which targets quasars with M_1450_{<}-27 at 2.8<=z<5 in an area of ~7600deg^2^ of the Sloan Digital Sky Survey (SDSS) footprint with 90{deg}<RA<270{deg}. Based on a near-infrared/infrared JKW2 color cut, the ELQS selection efficiently uses random forest methods to classify quasars and to estimate photometric redshifts; this scheme overcomes some of the difficulties of pure optical quasar selection at z~3. As a result, we retain a completeness of >70% over z~3.0-5.0 at m_i_<~17.5, limited toward fainter magnitudes by the depth of the Two Micron All Sky Survey. The presented quasar catalog consists of a total of 270 objects, of which 39 are newly identified in this work with spectroscopy obtained at the Vatican Advanced Technology Telescope and the MMT 6.5m telescope. In addition to the high completeness, which allowed us to discover new quasars in the already well-surveyed SDSS North Galactic Cap, the efficiency of our selection is relatively high at ~79%. Using 120 objects of this quasar sample we are able to extend the previously measured optical quasar luminosity function (QLF) by one magnitude toward the bright end at 2.8<=z<=4.5. A first analysis of the QLF suggests a relatively steep bright-end slope of {beta}~-4 for this sample. This result contrasts with previous results in the same redshift range, which find a much flatter slope around {beta}~-2.5, but agrees with recent measurements of the bright-end slope at lower and higher redshifts. Our results constrain the bright-end slope at z=2.8-4.5 to {beta}{<}-2.94 with a 99% confidence.
- ID:
- ivo://CDS.VizieR/J/ApJS/243/5
- Title:
- The ELQS in the PS1 footprint (PS-ELQS)
- Short Name:
- J/ApJS/243/5
- Date:
- 08 Mar 2022 13:10:17
- Publisher:
- CDS
- Description:
- We present the results of the Extremely Luminous Quasar Survey in the 3{pi} survey of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; PS1). This effort applies the successful quasar selection strategy of the Extremely Luminous Survey in the Sloan Digital Sky Survey footprint (~12000deg^2^) to a much larger area (~21486deg^2^). This spectroscopic survey targets the most luminous quasars (M_1450_<=-26.5; m_i_<=18.5) at intermediate redshifts (z>=2.8). Candidates are selected based on a near-infrared JKW2 color cut using WISE AllWISE and 2MASS photometry to mainly reject stellar contaminants. Photometric redshifts (z_reg_) and star-quasar classifications for each candidate are calculated from near-infrared and optical photometry using the supervised machine learning technique random forests. We select 806 quasar candidates at z_reg_>=2.8 from a parent sample of 74318 sources. After exclusion of known sources and rejection of candidates with unreliable photometry, we have taken optical identification spectra for 290 of our 334 good PS-ELQS candidates. We report the discovery of 190 new z>=2.8 quasars and an additional 28 quasars at lower redshifts. A total of 44 good PS-ELQS candidates remain unobserved. Including all known quasars at z>=2.8, our quasar selection method has a selection efficiency of at least 77%. At lower declinations, -30<=DEC<=0, we approximately treble the known population of extremely luminous quasars. We provide the PS-ELQS quasar catalog with a total of 592 luminous quasars (m_i_<=18.5, z>=2.8). This unique sample will not only be able to provide constraints on the volume density and quasar clustering of extremely luminous quasars, but also offers valuable targets for studies of the intergalactic medium.
21657. The ENACS Catalogue. V.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/399
- Title:
- The ENACS Catalogue. V.
- Short Name:
- J/A+AS/129/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalogue resulting from the ESO Nearby Abell Cluster Survey (the ENACS), which contains redshifts and magnitudes for 5634 galaxies in the directions of 107 rich, nearby southern Abell cluster candidates. We describe the contents of the catalogue and discuss the results of a comparison between the ENACS catalogue and the COSMOS Galaxy Catalogue. When cross-correlating the two catalogues we find that, at least in the areas of the ENACS clusters, the completeness of the COSMOS catalogue is somewhat lower than was estimated previously for the carefully analyzed and well-calibrated part of the COSMOS catalogue known as the Edinburgh-Durham Southern Galaxy Survey (EDSGC). The galaxy positions in the COSMOS and ENACS catalogues are found to be on the same system to within about one arcsecond. For the clusters for which the photometry in the ENACS and COSMOS catalogues is based on the same survey plates, the two magnitude scales agree very well. We confirm that the photometric calibration in the EDSGC subset of the COSMOS catalogue is of higher quality than in the EDSGC complement. The ENACS galaxy samples are unbiased subsets of the COSMOS catalogue as far as the projected galaxy distribution is concerned, except in only a few cases. We summarize how the ENACS galaxy samples are subsets of the COSMOS catalogues in the ENACS apertures, with respect to magnitude. For the ENACS catalogue as a whole, we describe the apparent incompleteness at faint magnitudes and towards higher redshifts. Finally, we provide some detailed information about the ENACS catalogue that is essential for its proper statistical use and we summarize some facts that must be remembered when selecting subsets of galaxies from it. Objects:
21658. The epoch ICRF
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/2633
- Title:
- The epoch ICRF
- Short Name:
- J/MNRAS/430/2633
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The epoch International Celestial Reference Frame (epoch ICRF) is proposed as a new concept in order to consider the effect of apparent proper motion of the position of a radio source due to acceleration of the spatial origin of the ICRF, the centre of mass of the Solar system. This apparent proper motion has a magnitude of approximately 5.8-microarcsec ({mu}as) per year, and for the 30-year very long baseline interferometry (VLBI) observational history these position variations will exceed 100{mu}as. We show that the dipole structure of the apparent proper motions leads to global rotation in the ICRF2 and the main term, the shift of direction of the origin of right ascension, reaches 25{mu}as per century. The 'epoch ICRF' is constructed using epoch positions at J2000.0 and apparent proper motions of radio sources, which are reported here for 295 ICRF2-defining sources.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A76
- Title:
- The ESO DIBs Large Exploration Survey
- Short Name:
- J/A+A/606/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The carriers of the diffuse interstellar bands (DIBs) are largely unidentified molecules ubiquitously present in the interstellar medium (ISM). After decades of study, two strong and possibly three weak near-infrared DIBs have recently been attributed to the C^+^_60_ fullerene based on observational and laboratory measurements. There is great promise for the identification of the over 400 other known DIBs, as this result could provide chemical hints towards other possible carriers. In an effort to systematically study the properties of the DIB carriers, we have initiated a new large-scale observational survey: the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES). The main objective is to build on and extend existing DIB surveys to make a major step forward in characterising the physical and chemical conditions for a statistically significant sample of interstellar lines-of-sight, with the goal to reverse-engineer key molecular properties of the DIB carriers. EDIBLES is a filler Large Programme using the Ultraviolet and Visual Echelle Spectrograph at the Very Large Telescope at Paranal, Chile. It is designed to provide an observationally unbiased view of the presence and behaviour of the DIBs towards early-spectral-type stars whose lines-of-sight probe the diffuse-to-translucent ISM. Such a complete dataset will provide a deep census of the atomic and molecular content, physical conditions, chemical abundances and elemental depletion levels for each sightline. Achieving these goals requires a homogeneous set of high-quality data in terms of resolution (R~70000-100000), sensitivity (S/N up to 1000 per resolution element), and spectral coverage (305-1042nm), as well as a large sample size (100+ sightlines). In this first paper the goals, objectives and methodology of the EDIBLES programme are described and an initial assessment of the data is provided.
- ID:
- ivo://CDS.VizieR/J/A+A/310/8
- Title:
- The ESO Nearby Abell Cluster Survey I.
- Short Name:
- J/A+A/310/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of the ESO Key-programme on "Structure and Dynamics of Rich Galaxy Clusters" (which we will henceforth refer to as the ESO Nearby Abell Cluster Survey - or ENACS). We discuss the sample of clusters for which data were obtained, and the observational programme of spectroscopy and photometry that we carried out. The final database contains a total of 5634 galaxies in the directions of 107 clusters from the catalogue by Abell, Corwin and Olowin 1989 (ACO hereafter) with richness R>=1 and mean redshifts z<=0.1.
