- ID:
- ivo://CDS.VizieR/J/A+A/643/A113
- Title:
- iz photometry of S190814bv ctp candidates
- Short Name:
- J/A+A/643/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg^2^ (23 deg^2^) - despite the relatively large distance of 267 52 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope (ENGRAVE) collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r 22 (resp. K 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total 50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M>~0:1M_{sun}_ to a high (>90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxytargeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/479/141
- Title:
- Iz photometry, RV and EW(Li) in IC 4665
- Short Name:
- J/A+A/479/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The so-called lithium depletion boundary (LDB) provides a secure and independent tool for deriving the ages of young open clusters. In this context, our goal is to determine membership for a sample of 147 photometrically selected candidates of the young open cluster IC 4665 and to use confirmed members to establish an age based on the LDB. Employing the FLAMES multi-object spectrograph on VLT/UT2, we have obtained intermediate-resolution spectra of the cluster candidates. The spectra were used to measure radial velocities and to infer the presence of the LiI 670.8nm doublet and H{alpha} emission.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A2
- Title:
- J-band variability of AGN
- Short Name:
- J/A+A/555/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral energy distribution and its variability are basic tools for understanding the physical processes operating in active galactic nuclei (AGN). In this paper we report the results of a one-year near infra red (NIR) and optical monitoring of a sample of 22 AGN known to be {gamma}-ray emitters, aimed at discovering correlations between optical and {gamma}-ray emission. We observed our objects with the Rapid Eye Mount (REM) telescope in J, H, K, and R bands nearly twice every month during their visibility window and derived light curves and spectral indexes. We also analyzed the {gamma}-ray data from the Fermi {gamma}-ray Space Telescope, making weekly averages.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1551
- Title:
- JCMT Gould Belt Survey: Serpens MWC 297
- Short Name:
- J/MNRAS/448/1551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450 and 850{mu}m observations of the Serpens MWC 297 region, part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey of nearby star-forming regions. Simulations suggest that radiative feedback influences the star formation process and we investigate observational evidence for this by constructing temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two-component model of the JCMT beam for a fixed dust opacity spectral index of {beta}=1.8. Within 40-arcsec of the B1.5Ve Herbig star MWC 297, the submillimetre fluxes are contaminated by free-free emission with a spectral index of 1.03+/-0.02, consistent with an ultracompact HII region and polar winds/jets. Contamination accounts for 73+/-5 per cent and 82+/-4 per cent of peak flux at 450{mu}m and 850 {mu}m, respectively. The residual thermal disc of the star is almost undetectable at these wavelengths. Young stellar objects (YSOs) are confirmed where SCUBA-2 850{mu}m clumps identified by the fellwalker algorithm coincide with Spitzer Gould Belt Survey detections. We identify 23 objects and use T_bol_ to classify nine YSOs with masses 0.09 to 5.1M_{sun}_. We find two Class 0, one Class 0/I, three Class I and three Class II sources. The mean temperature is 15+/-2K for the nine YSOs and 32+/-4K for the 14 starless clumps. We observe a starless clump with an abnormally high mean temperature of 46+/-2K and conclude that it is radiatively heated by the star MWC 297. Jeans stability provides evidence that radiative heating by the star MWC 297 may be suppressing clump collapse.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/4150
- Title:
- JCMT Gould Belt Survey: W40 complex
- Short Name:
- J/MNRAS/460/4150
- Date:
- 14 Jan 2022 11:14:19
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450{mu}m and 850{mu}m observations of the W40 complex in the Serpens-Aquila region as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) of nearby star-forming regions. We investigate radiative heating by constructing temperature maps from the ratio of SCUBA-2 fluxes using a fixed dust opacity spectral index, {beta}=1.8, and a beam convolution kernel to achieve a common 14.8-arcsec resolution. We identify 82 clumps ranging between 10 and 36K with a mean temperature of 20+/-3K. Clump temperature is strongly correlated with proximity to the external OB association and there is no evidence that the embedded protostars significantly heat the dust. We identify 31 clumps that have cores with densities greater than 10^5^cm^-3^. 13 of these cores contain embedded Class 0/I protostars. Many cores are associated with bright-rimmed clouds seen in Herschel 70{mu}m images. From JCMT HARP observations of the ^12^CO 3-2 line, we find contamination of the 850{mu}m band of up to 20 per cent. We investigate the free-free contribution to SCUBA-2 bands from large-scale and ultracompact HII regions using archival VLA data and find the contribution is limited to individual stars, accounting for 9 per cent of flux per beam at 450{mu}m or 12 per cent at 850{mu}m in these cases. We conclude that radiative heating has potentially influenced the formation of stars in the Dust Arc sub-region, favouring Jeans stable clouds in the warm east and fragmentation in the cool west.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/98
- Title:
- Jet kinematics of blazars at 43GHz with the VLBA
- Short Name:
- J/ApJ/846/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of {gamma}-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. Approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5pc (projected) of the core, and knots in BLLacs tending to decelerate near the core. Using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. We calculate the intrinsic brightness temperatures of the cores, T_b,int_^core^, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ~30% of T_b,int_^core^ measurements in the quasars and BLLacs deviate from equipartition values by a factor >10. This probably occurs during transient events connected with active states.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A122
- Title:
- JHK and IRAC photometry of Sh2-90 YSOs
- Short Name:
- J/A+A/566/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the star formation activity in the molecular complex associated with the Galactic HII region Sh2-90. We obtain the distribution of the ionized and cold neutral gas using radio-continuum and Herschel observations. We use near-infrared and Spitzer data to investigate the stellar content of the complex. We discuss the evolutionary status of embedded massive young stellar objects (MYSOs) using their spectral energy distribution.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/23
- Title:
- JHK' imaging photometry of Seyfert 1. I.
- Short Name:
- J/ApJS/141/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared JHK' imaging photometry was obtained of 331 AGNs consisting mainly of Seyfert 1 active galactic nuclei (AGNs) and quasars (QSOs). This sample was selected to cover a range of radio emission strength, redshift from z=0 to 1, and absolute B magnitude from M_B_=-29mag to -18mag. Among low-z AGNs with z<0.3, Seyfert 1-1.5 AGNs are distributed over a region from a location typical of "galaxies" to a location typical of "QSOs" in the two-color J-H to H-K' diagram, but Seyfert 1.8-2 AGNs are distributed around the location of "galaxies". Moreover, bright AGNs with respect to absolute B magnitude are distributed near the location of "QSOs," while faint AGNs are near the location of "galaxies". The distribution of such low-z AGNs in this diagram was found to have little dependence on their 6 cm radio flux. The near-infrared colors of the AGNs observed with an aperture of 7 pixels (7.49") are more QSO-like than those observed with larger apertures up to 15 pixels (16.1"). This aperture effect may be explained by contamination from the light of host galaxies within larger apertures. This effect is more prominent for less luminous AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/31
- Title:
- JHK' imaging photometry of Seyfert 1. II.
- Short Name:
- J/ApJS/141/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of 226 AGNs in the near-infrared J, H, and K' bands are presented along with the analysis of the observations for variability. Our sample consists mainly of Seyfert 1 AGNs and QSOs. About a quarter of the objects in each category are radio loud. The AGNs in the entire sample have the redshifts spanning the range from z=0 to 1, and the absolute magnitudes from M_B_=-29 to -18. All the objects were observed twice, and their variability was measured by differential photometry. A reduction method of differential photometry, optimized to the analysis of extended images, has been developed. The systematic error in variability arising from AGNs of highly extended images is estimated to be less than 0.01mag in each of the J, H, and K' bands. The systematic error arising from the flat-fielding is negligible for most AGNs, although it is more than 0.1mag for some particular cases. The overall average flat-fielding error is 0.03mag for the image pairs. We find that these systematic errors are superseded by statistical errors, and the overall average total systematic and statistical errors amounts to 0.05mag in the measured variability in each band.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/464
- Title:
- JHK lightcurves of red giants in the SMC
- Short Name:
- J/MNRAS/448/464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long-term JHK light curves have recently become available for large numbers of the more luminous stars in the Small Magellanic Cloud (SMC). We have used these JHK light curves, along with OGLE (Optical Gravitational Lensing Experiment) V and I light curves, to examine the variability of a sample of luminous red giants in the SMC which show prominent long secondary periods (LSPs). The origin of the LSPs is currently unknown. In oxygen-rich stars, we found that while most broad-band colours (e.g. V- I) get redder when an oxygen-rich star dims during its LSP cycle, the J-K colour barely changes and sometimes becomes bluer. We interpret the J-K colour changes as being due to increasing water vapour absorption during declining light caused by the development of a layer of dense cool gas above the photosphere. This result and previous observations which indicate the development of a chromosphere between minimum to maximum light suggest that the LSP phenomenon is associated with the ejection of matter from the stellar photosphere near the beginning of light decline. We explore the possibility that broad-band light variations from the optical to the near-infrared regions can be explained by either dust absorption by ejected matter or large spots on a rotating stellar surface. However, neither model is capable of explaining the observed light variations in a variety of colour-magnitude diagrams. We conclude that some other mechanism is responsible for the light variations associated with LSPs in red giants.
