- ID:
- ivo://CDS.VizieR/J/ApJ/804/114
- Title:
- Parameter-estimation performance with LIGO
- Short Name:
- J/ApJ/804/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Advanced ground-based gravitational-wave (GW) detectors begin operation imminently. Their intended goal is not only to make the first direct detection of GWs, but also to make inferences about the source systems. Binary neutron-star mergers are among the most promising sources. We investigate the performance of the parameter-estimation (PE) pipeline that will be used during the first observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) in 2015: we concentrate on the ability to reconstruct the source location on the sky, but also consider the ability to measure masses and the distance. Accurate, rapid sky localization is necessary to alert electromagnetic (EM) observatories so that they can perform follow-up searches for counterpart transient events. We consider PE accuracy in the presence of non-stationary, non-Gaussian noise. We find that the character of the noise makes negligible difference to the PE performance at a given signal-to-noise ratio. The source luminosity distance can only be poorly constrained, since the median 90% (50%) credible interval scaled with respect to the true distance is 0.85 (0.38). However, the chirp mass is well measured. Our chirp-mass estimates are subject to systematic error because we used gravitational-waveform templates without component spin to carry out inference on signals with moderate spins, but the total error is typically less than 10^-3^M_{sun}_. The median 90% (50%) credible region for sky localization is ~600deg^2^ (~150deg^2^), with 3% (30%) of detected events localized within 100deg^2^. Early aLIGO, with only two detectors, will have a sky-localization accuracy for binary neutron stars of hundreds of square degrees; this makes EM follow-up challenging, but not impossible.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/899/55
- Title:
- Parameters of protoplanetary disks in 5 SFRs
- Short Name:
- J/ApJ/899/55
- Date:
- 14 Mar 2022 07:11:43
- Publisher:
- CDS
- Description:
- Spatial correlations among protoplanetary disk orientations carry unique information on physics of multiple-star formation processes. We select five nearby star-forming regions that comprise a number of protoplanetary disks with spatially resolved images with ALMA and Hubble Space Telescope, and we search for the mutual alignment of the disk axes. Specifically, we apply the Kuiper test to examine the statistical uniformity of the position angle (PA: the angle of the major axis of the projected disk ellipse measured counterclockwise from the north) distribution. The disks located in the star-forming regions, except the Lupus clouds, do not show any signature of the alignment, supporting the random orientation. Rotational axes of 16 disks with spectroscopic measurement of PA in the LupusIII cloud, a subregion of the Lupus field, however, exhibit a weak and possible departure from the random distribution at a 2{sigma} level, and the inclination angles of the 16 disks are not uniform as well. Furthermore, the mean direction of the disk PAs in the LupusIII cloud is parallel to the direction of its filament structure and approximately perpendicular to the magnetic field direction. We also confirm the robustness of the estimated PAs in the Lupus clouds by comparing the different observations and estimators based on three different methods, including sparse modeling. The absence of the significant alignment of the disk orientation is consistent with the turbulent origin of the disk angular momentum. Further observations are required to confirm/falsify the possible disk alignment in the Lupus III cloud.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1623
- Title:
- PHASES diff. astrometry data archive. II.
- Short Name:
- J/AJ/140/1623
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture measurements covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits for 20 binary stars. In some cases, radial velocity observations exist to constrain the full three-dimensional orbit and determine component masses. The visual orbit of one of these binaries - {alpha} Com (HD 114378) - shows that the system is likely to have eclipses, despite its very long period of 26 years. The next eclipse is predicted to be within a week of 2015 January 24.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1657
- Title:
- PHASES diff. astrometry data archive. V.
- Short Name:
- J/AJ/140/1657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Palomar High-precision Astrometric Search for Exoplanet Systems monitored 51 subarcsecond binary systems to evaluate whether tertiary companions as small as Jovian planets orbited either the primary or secondary stars, perturbing their otherwise smooth Keplerian motions. Six binaries are presented that show evidence of substellar companions orbiting either the primary or secondary star. Of these six systems, the likelihoods of two of the detected perturbations to represent real objects are considered to be "high confidence," while the remaining four systems are less certain and will require continued observations for confirmation.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1579
- Title:
- PHASES differential astrometry data archive
- Short Name:
- J/AJ/140/1579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) monitored 51 subarcsecond binary systems to determine precision binary orbits, study the geometries of triple and quadruple star systems, and discover previously unknown faint astrometric companions as small as giant planets. PHASES measurements made with the Palomar Testbed Interferometer (PTI) from 2002 until PTI ceased normal operations in late 2008 are presented. Infrared differential photometry of several PHASES targets were measured with Keck Adaptive Optics and are presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/768/74
- Title:
- PHIBSS: CO observations of star-forming galaxies
- Short Name:
- J/ApJ/768/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present PHIBSS, the IRAM Plateau de Bure high-z blue sequence CO(3-2) survey of the molecular gas properties in massive, main-sequence star-forming galaxies (SFGs) near the cosmic star formation peak. PHIBSS provides 52 CO detections in two redshift slices at z~1.2 and 2.2, with log(M_*_(M_{sun}_))>=10.4 and log(SFR(M_{sun}_/yr))>=1.5. Including a correction for the incomplete coverage of the M_*_-SFR plane, and adopting a "Galactic" value for the CO-H_2_ conversion factor, we infer average gas fractions of ~0.33 at z~1.2 and ~0.47 at z~2.2. Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong star formation feedback. Most of the z~1-3 SFGs are rotationally supported turbulent disks. The sizes of CO and UV/optical emission are comparable. The molecular-gas-star-formation relation for the z=1-3 SFGs is near-linear, with a ~0.7Gyr gas depletion timescale; changes in depletion time are only a secondary effect. Since this timescale is much less than the Hubble time in all SFGs between z~0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years. At given z and M_*_, gas fractions correlate strongly with the specific star formation rate (sSFR). The variation of sSFR between z~0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.
- ID:
- ivo://CDS.VizieR/J/AJ/148/72
- Title:
- Photometry & interferometry of nearby secondaries
- Short Name:
- J/AJ/148/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To improve the statistics of hierarchical multiplicity, secondary components of wide nearby binaries with solar-type primaries were surveyed at the SOAR telescope for evaluating the frequency of subsystems. Images of 17 faint secondaries were obtained with the SOAR Adaptive Module that improved the seeing; one new 0.2'' binary was detected. For all targets, photometry in the g', i', z' bands is given. Another 46 secondaries were observed by speckle interferometry, resolving 7 close subsystems. Adding literature data, the binarity of 95 secondary components is evaluated. We found that the detection-corrected frequency of secondary subsystems with periods in the well-surveyed range from 10^3^ to 10^5^ days is 0.21+/-0.06--same as the normal frequency of such binaries among solar-type stars, 0.18. This indicates that wide binaries are unlikely to be produced by dynamical evolution of N-body systems, but are rather formed by fragmentation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/395/907
- Title:
- PISCO speckle observations in 2007
- Short Name:
- J/MNRAS/395/907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present relative astrometric measurements of visual binaries made during the first semester of 2007, with the Pupil Interferometry Speckle camera and COronagraph (PISCO) at the 102-cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 226 new measurements of 214 objects, with angular separations in the range 0.15-4.5arcsec, and an average accuracy of 0.013arcsec. The mean error on the position angles is. Most of the position angles could be determined without the usual 180{deg} ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files. We also present the new orbits we have computed for ADS 7871, 7982 and 8128, for which our measurements lead to large residuals and/or for which the revision is justified by the significant number of observations made since the publication of the previous orbit.
- ID:
- ivo://CDS.VizieR/J/AN/330/55
- Title:
- PISCO speckle observations in 2006
- Short Name:
- J/AN/330/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present relative astrometric measurements of visual binaries made during the second semester of 2006, with the speckle camera PISCO at the 102cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 175 new measurements of 169 objects, with angular separations in the range 0.1"-4.2", and an average accuracy of 0.01". The mean error on the position angles is 0.6{deg}. Most of the position angles could be determined without the usual 180{deg} ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files.We also present the new orbits we have computed for ADS 11479, 11584 and 16538, for which our measurements lead to large residuals and/or for which the revision was justified by the significant number of observations made since the last orbit computation.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A64
- Title:
- Position difference vectors and of the jets
- Short Name:
- J/A+A/651/A64
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We aim to study the relative positions of quasar emission centers at different wavelengths in order to help link the various realizations of the International Celestial Reference System (ICRS), and to unveil systematic uncertainties and individual source behavior at different wavelengths. We based our study on four catalogs representing the ICRS, the ICRF3 positions in the three VLBI bands X, K, and Ka, and the Gaia EDR3 catalog in optical wavelengths. We complemented radio source positions with jet kinematics results from the MOJAVE team, allowing us to obtain jet directions on the sky. A six-parameter deformation model was used to remove systematic uncertainties present in the different catalogs. For a set of 194 objects common to the four catalogs and to the objects whose jet kinematics was studied by the MOJAVE team, we computed the orientation between positions at the different wavelengths and with respect to the directions of the jets. We find that the majority of these objects have their radio-to-optical vector along the jet, with the optical centroid downstream from the radio centroids, and that the K and Ka centroids are preferably upstream in the jet with respect to the X centroid, which is consistent with the paradigm of a simple core-jet model. For a population of multiwavelength positions aligned along the jet, astrometric information can therefore be used to measure the direction of the jet independently of imaging. In addition, we find several sources for which the optical centroid coincides with stationary radio features with a relatively high fraction of polarization, indicating optical emission dominated by a synchrotron process in the jet.
