- ID:
- ivo://CDS.VizieR/J/ApJ/813/39
- Title:
- LIGO gravitational-wave (GW) searches from SNRs
- Short Name:
- J/ApJ/813/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering F-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4x10^-25^ on intrinsic strain, 2x10^-7^ on fiducial ellipticity, and 4x10^-5^ on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/879/10
- Title:
- 2015-2017 LIGO obs. analysis for 221 pulsars
- Short Name:
- J/ApJ/879/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a search for gravitational waves from 221 pulsars with rotation frequencies >~10Hz. We use advanced LIGO data from its first and second observing runs spanning 2015-2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l=m=2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l=2, m=1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l=m=2 mode search, we provide updated upper limits on the gravitational-wave amplitude, mass quadrupole moment, and fiducial ellipticity for 167 pulsars, and the first such limits for a further 55. For 20 young pulsars these results give limits that are below those inferred from the pulsars' spin-down. For the Crab and Vela pulsars our results constrain gravitational-wave emission to account for less than 0.017% and 0.18% of the spin-down luminosity, respectively. For the recycled millisecond pulsar J0711-6830 our limits are only a factor of 1.3 above the spin-down limit, assuming the canonical value of 10^38^kg.m^2^ for the star's moment of inertia, and imply a gravitational-wave-derived upper limit on the star's ellipticity of 1.2x10^-8^. We also place new limits on the emission amplitude at the rotation frequency of the pulsars.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/12
- Title:
- LIGO/Virgo gravitational-wave (GW) bursts with GRBs
- Short Name:
- J/ApJ/760/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the distance to the progenitor, under the optimistic assumption of a gravitational-wave emission energy of 10^-2^M_{sun}_c^2^ at 150Hz, with a median limit of 17Mpc. For short-hard GRBs we place exclusion distances on binary neutron star and neutron-star-black-hole progenitors, using astrophysically motivated priors on the source parameters, with median values of 16Mpc and 28Mpc, respectively. These distance limits, while significantly larger than for a search that is not aided by GRB satellite observations, are not large enough to expect a coincidence with a GRB. However, projecting these exclusions to the sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015, we find that the detection of gravitational waves associated with GRBs will become quite possible.
- ID:
- ivo://cvo.naoc/data/gmg240/yfosc/conesearch
- Title:
- Lijiang 2.4m Telescope yfosc catalog
- Short Name:
- GMG240.YFOSC.CS
- Date:
- 08 May 2019 17:01:49
- Publisher:
- China-VO
- Description:
- the conesearch service for Gaomeigu 2.4m telescope, which contains the catalog of yfosc
- ID:
- ivo://CDS.VizieR/J/PASP/131/D4101
- Title:
- Likely Pleiades members with Gaia DR2
- Short Name:
- J/PASP/131/D4101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an investigation on fundamental astrophysical properties of the Pleiades cluster (M 45) using high-precision astrometric and photometric data from the Gaia Data Release 2 (Gaia-DR2). To obtain reliable cluster members, a machine-learning (ML) method is used to compute membership probabilities for 31462 sample stars within a radius of 6.5{deg} from the cluster center, both the astrometric and photometric data are taken into account. We obtain a total number of 1454 likely cluster members with membership probabilities larger than 0.6, including a well-known white dwarf (LB 1497) with a high membership probability of ~0.96. We find a well-defined relationship between the parallaxes and proper motions of the cluster members, the most likely explanation for the relationship is that the depth effect of the cluster along the line of sight must be taken into consideration. Using Monte Carlo simulations, the most likely distance, proper motion, and radial velocity of the cluster are determined to be D=136.0+/-0.1pc, (<{mu}_{alpha}_cos{delta}>, <{mu}_{delta}_>)=(+20.141+/-0.093, -45.536+/ -0.081)mas/yr, and <V_r_>=+5.8+/-0.1km/s, respectively. It is found that the likely cluster members extend outward to a limiting radius of R_lim_=310'+/-12' (12.3+/-0.5pc) from the cluster center, and the total mass of the cluster within this radius is M_tot_=721+/-93M_{sun}_. We find clear evidence for the presence of spatial mass segregation in this young cluster by analyzing the photometry and spatial positions of the likely cluster members. Interestingly, we also find that four high-mass cluster members with high membership probabilities (>0.99) are being ejected from the inner region of the cluster, they may have formed via close encounters between single and binary stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/L21
- Title:
- Limits on gamma-ray emission from galaxy clusters
- Short Name:
- J/ApJ/795/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters are predicted to produce {gamma}-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z<0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3x10^-11^ photons/cm2/s (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5x10^44^ photons/s. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and {gamma}-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.
- ID:
- ivo://CDS.VizieR/J/A+A/359/227
- Title:
- Lindroos binary systems X-ray emission
- Short Name:
- J/A+A/359/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the X-ray emission from binary systems extracted from the Lindroos catalogue (Lindroos, 1986A&A...156..223L) based on the ROSAT All-Sky survey as well as ROSAT PSPC and HRI pointings. The studied sample consists of visual binary systems comprised of early-type primaries and late-type secondaries. The ages of the systems were determined by Lindroos (1985, Cat. II/127) from uvby{beta} photometry of the primaries. These ages range between 33 and 135Myr, so if the late-type secondaries are physically bound to the early-type primaries, they could be Post-T Tauri stars (PTTS). We have found strong X-ray emission from several secondaries. This fact together with their optical and IR data, make them bona fide PTTS candidates. We have also detected X-ray emission from several early-type primaries and, in particular, from most of the late-B type stars. Because their HRI hardness ratios are similar to those from resolved late-type stars, the presence of an unresolved late-type companion seems to be the cause of this emission.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/L39
- Title:
- Lindsay 1 spectroscopy for 34 targets
- Short Name:
- J/MNRAS/465/L39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lindsay 1 is an intermediate-age (~=8Gyr) massive cluster in the Small Magellanic Cloud. Using VLT FORS2 spectra of 16 probable cluster members on the lower red giant branch of the cluster, we measure CN and CH band strengths (at ~=3883 and 4300{AA}, respectively), along with carbon and nitrogen abundances and find that a sub-population of stars has significant nitrogen enrichment. A lack of spread in carbon abundances excludes evolutionary mixing as the source of this enrichment, so we conclude that this is evidence of multiple populations. Therefore, Lindsay 1 is the youngest cluster to show such variations, implying that the process triggering the onset of multiple populations must operate until at least redshift ~1.
- ID:
- ivo://CDS.VizieR/J/AJ/146/21
- Title:
- LINEAR. II. Catalog of RR Lyrae stars
- Short Name:
- J/AJ/146/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of ~5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5kpc and 30kpc over ~8000 deg^2^ of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of ~4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q=0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.
- ID:
- ivo://CDS.VizieR/J/AJ/146/101
- Title:
- LINEAR. III. Catalog of periodic variables
- Short Name:
- J/AJ/146/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10000deg^2^ of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ~0.03mag at r=15 to ~0.20mag at r=18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ~200000 most probable candidate variables with r<17 and visually confirmed and classified ~7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars ({beta} Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median period increases from 5.9hr to 8.8hr. These large samples of robustly classified variable stars will enable detailed statistical studies of the Galactic structure and physics of binary and other stars and we make these samples publicly available.