- ID:
- ivo://CDS.VizieR/J/ApJ/848/L16
- Title:
- Counterpart of GW170817. I. DECam obs.
- Short Name:
- J/ApJ/848/L16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Dark Energy Camera (DECam) discovery of the optical counterpart of the first binary neutron star merger detected through gravitational-wave emission, GW170817. Our observations commenced 10.5hr post-merger, as soon as the localization region became accessible from Chile. We imaged 70deg^2^ in the i and z bands, covering 93% of the initial integrated localization probability, to a depth necessary to identify likely optical counterparts (e.g., a kilonova). At 11.4hr post-merger we detected a bright optical transient located 10.6" from the nucleus of NGC 4993 at redshift z=0.0098, consistent (for H_0_=70km/s/Mpc) with the distance of 40+/-8Mpc reported by the LIGO Scientific Collaboration and the Virgo Collaboration (LVC). At detection the transient had magnitudes of i=17.3 and z=17.4, and thus an absolute magnitude of Mi=-15.7, in the luminosity range expected for a kilonova. We identified 1500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC 4993 as the only remaining plausible counterpart, and reject chance coincidence at the 99.5% confidence level. We therefore conclude that the optical counterpart we have identified near NGC 4993 is associated with GW170817. This discovery ushers in the era of multi-messenger astronomy with gravitational waves and demonstrates the power of DECam to identify the optical counterparts of gravitational-wave sources.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/203/15
- Title:
- Counterparts to 1.4GHz sources in ECDF-S
- Short Name:
- J/ApJS/203/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a sample of 883 sources detected in a deep Very Large Array survey at 1.4GHz in the Extended Chandra Deep Field South. This paper focuses on the identification of their optical and infrared (IR) counterparts. We use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. We find a reliable counterpart for 95% of our radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, we are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). We also investigate the X-ray properties of the radio sources using the Chandra 4Ms and 250ks observations. In particular, we use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of our analysis are collected in a new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population.
- ID:
- ivo://CDS.VizieR/J/A+A/461/631
- Title:
- Counterparts to massive X-ray binaries
- Short Name:
- J/A+A/461/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-ray and gamma-ray observatory INTEGRAL has discovered large numbers of new hard X-ray sources, many of which are believed to be high mass X-ray binaries. However, for a significant fraction, their counterparts remain unidentified. We explore the use of photometric catalogues to find optical counterparts to high mass X-ray binaries and search for objects likely to be early-type stars within the error circles of several INTEGRAL sources. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
- ID:
- ivo://CDS.VizieR/J/ApJ/405/498
- Title:
- Counts and spectral indices at 8.44GHz
- Short Name:
- J/ApJ/405/498
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the VLA to make deep images of two 7x7' fields at 8.44 GHz with 10" resolution. With an rms noise of 3.2 and 5.1 {micro}Jy, respectively, in the two fields, we compiled a catalog of 82 sources. The normalized differential 8.44 GHz counts are similar to those at 1.41 and 4.86 GHz. All show a similarly steep submillijansky slope, which is only somewhat flatter than that expected for a nonevolving Euclidean population ({gamma}=2.5). Microjansky radio sources at 4.86 GHz have been identified with faint blue galaxies (18<~V<~28 mag). We argue that their expected median redshift is about 0.5-0.75. Hence, cosmological evolution may be needed to explain the steep slope of the microjansky counts. The 8.44 GHz counts must converge with slope {gamma}<2.0 below S(8.44)~300 nJy, or they would exceed the available field galaxy counts down to V~28 mag, and they must permanently converge below S(8.44)~20 nJy, or their integrated sky brightness would distort the observed thermal cosmic background radiation spectrum at centimeter wavelengths. The estimated 31.5 GHz sky brightness from nanojansky to jansky levels is <36 {micro}K (3{sigma}). Even if weak radio sources cluster on scales of degrees as faint galaxies do, their anisotropic contribution to the COBE DMR experiment (with 7deg FWHM-beam) would not exceed ~1.2{micro}K.
- ID:
- ivo://CDS.VizieR/J/A+A/600/A1
- Title:
- Coupling factors of 5166 KIC
- Short Name:
- J/A+A/600/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The power of asteroseismology relies on the capability of global oscillations to infer the stellar structure. For evolved stars, we benefit from unique information directly carried out by mixed modes that probe their radiative cores. This third article of the series devoted to mixed modes in red giants focuses on their coupling factors, which have remained largely unexploited up to now. With the measurement of coupling factors, we intend to give physical constraints on the regions surrounding the radiative core and the hydrogen-burning shell of subgiants and red giants. A new method for measuring the coupling factor of mixed modes was implemented, which was derived from the method recently implemented for measuring period spacings. This new method was automated so that it could be applied to a large sample of stars. Coupling factors of mixed modes were measured for thousands of red giants. They show specific variation with mass and evolutionary stage. Weak coupling is observed for the most evolved stars on the red giant branch only; large coupling factors are measured at the transition between subgiants and red giants as well as in the red clump. The measurement of coupling factors in dipole mixed modes provides a new insight into the inner interior structure of evolved stars. While the large frequency separation and the asymptotic period spacings probe the envelope and core, respectively, the coupling factor is directly sensitive to the intermediate region in between and helps determine its extent. Observationally, the determination of the coupling factor is a prior to precise fits of the mixed-mode pattern and can now be used to address further properties of the mixed-mode pattern, such as the signature of buoyancy glitches and core rotation.
- ID:
- ivo://CDS.VizieR/J/ApJS/160/319
- Title:
- COUP: observations and source lists
- Short Name:
- J/ApJS/160/319
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a description of the data reduction methods and the derived catalog of more than 1600 X-ray point sources from the exceptionally deep 2003 January Chandra X-Ray Observatory (Chandra) observation of the Orion Nebula Cluster and embedded populations around OMC-1. The observation was obtained with Chandra's Advanced CCD Imaging Spectrometer (ACIS) and has been nicknamed the Chandra Orion Ultradeep Project (COUP). With an 838ks exposure made over a continuous period of 13.2 days, the COUP observation provides the most uniform and comprehensive data set on the X-ray emission of normal stars ever obtained in the history of X-ray astronomy.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1602
- Title:
- Cousins RI photometry in IC 348
- Short Name:
- J/AJ/127/1602
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The extremely young cluster IC 348 has been monitored photometrically over five observing seasons from 1998 December 10 to 2003 March 26 in Cousins I with a 0.6m telescope at Van Vleck Observatory. Twenty-eight periodic variables and 16 irregular variables have been identified. The variability study is most sensitive for stars with I<14.3mag; at that brightness level, we find that 24 of the 27 known pre-main-sequence (PMS) cluster members in the monitored field are variables, illustrating the value of photometric monitoring for identifying PMS cluster members. Among this brighter sample, 14 of the 16 known K or M-type weak-line T Tauri stars (WTTS) were found to be periodic variables, while all five of the known classical T Tauri stars (CTTS) were found to be irregular variables. In the full sample, which includes 150 stars with I as faint as 18, we find that 40% of the 63 WTTS are detected as variables, nearly all of them periodic, while 55% of the 20 CTTS are also detected as variable, with none of them periodic.
- ID:
- ivo://CDS.VizieR/J/MNRAS/376/580
- Title:
- Cousins RI photometry of NGC 2169
- Short Name:
- J/MNRAS/376/580
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used Cousins RI CCD photometry from the Isaac Newton telescope and intermediate-resolution spectroscopy from the Gemini North telescope to identify and characterize low-mass (0.15<M/M_{sun}_<1.3) pre-main-sequence stars in the young open cluster NGC 2169. Isochrone fitting to the high- and low-mass populations yields an intrinsic distance modulus of 10.13^+0.06^_-0.09_mag and a model-dependent age of 9+/-2Myr. Compared to the nearby, kinematically defined groups of a similar age, NGC 2169 has a large low-mass population which potentially offers a more precise statistical investigation of several aspects of star formation and early stellar evolution. By modelling the distribution of low-mass stars in the IC versus RC IC diagram, we find that any age spread among cluster members has a Gaussian full width at half-maximum (FWHM) 2.5Myr. A young age and a small age spread (<10Myr) are supported by the lack of significant lithium depletion in the vast majority of cluster members. There is no clear evidence for accretion or warm circumstellar dust in the low-mass members of NGC 2169, bolstering the idea that strong accretion has ceased and inner discs have dispersed in almost all low-mass stars by ages of 10Myr.
- ID:
- ivo://CDS.VizieR/J/A+A/417/107
- Title:
- CO velocities in southern HII regions
- Short Name:
- J/A+A/417/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ^12^CO(1-0), ^12^CO(2-1) and/or ^13^CO(1-0) observations in the direction of HII regions located in the southern Galactic plane. The CO lines have been fitted with gaussian lines. For each direction (indicated by the galactic coordinates put in the source identification) we detect several components. The parameter, central position, line width and intensity of every component are listed in tables 2 and 3. In addition, we indicate, in the last two columns the velocity from radio and H{alpha} data of the pointed HII region.
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/3445
- Title:
- Covering factor of warm dust in quasars
- Short Name:
- J/MNRAS/430/3445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By combining newly obtained infrared photometric data from the All-Sky Data Release of the Wide-field Infrared Survey Explorer with spectroscopic data from the Seventh Data Release of the Sloan Digital Sky Survey, we study the covering factor of warm dust (CFWD) for a large quasar sample, as well as the relations between CFWD and other physical parameters of quasars. We find a strong correlation between the flux ratio in the mid-infrared to near-ultraviolet and the slope of the near-ultraviolet spectra, which is interpreted as a dust extinction effect. After correcting for dust extinction utilizing the above correlation, we examine the relations between CFWD and active galactic nucleus properties: bolometric luminosity (L_bol_), black hole mass (M_BH_) and Eddington ratio (L/L_Edd_). We confirm the anticorrelation between CFWD and L_bol_. Further, we find that CFWD is anticorrelated with M_BH_ but is independent of L/L_Edd_. Radio-loud quasars are found to follow the same correlations as radio-quiet quasars. Monte Carlo simulations show that the anisotropy of the UV-optical continuum of the accretion disc can have a significant effect, but is not likely to dominate the CFWD-L_bol_ correlation.
