Search Publications
Machine learning for fast transients for the Deeper, Wider, Faster programme with the Removal Of BOgus Transients (ROBOT) pipeline
Mahabal, Ashish; Zhang, Jielai; Cooke, Jeff +3 more
The Deeper, Wider, Faster (DWF) programme is optimized to detect fast transients that show luminosity changes on time-scales of sub-second to days using fast cadence simultaneous observations and rapid response follow up. One of the significant bottlenecks in DWF is the time required to assess candidates for rapid follow up and to manually inspect…
Optical and near-infrared data and modelling of nova V5668 Sgr
Lawrence, S. S.; Sokolovsky, K. V.; Diaz, M. +4 more
We present Hubble Space Telescope optical images, Keck-OSIRIS near-infrared (NIR) integral field spectroscopy data cubes and Keck-Near InfraRed Camera-2 (NIRC2) NIR images of nova V5668 Sgr from 2016 to 2019. The observations indicate enhanced emission at the polar caps and equatorial torus for low-ionization lines, and enhanced high-ionization em…
Spatiokinematic models of five nova remnants: correlations between nova shell axial ratio, expansion velocity, and speed class
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +3 more
We present long-slit intermediate-dispersion spectroscopic observations and narrow-band direct imaging of four classical nova shells, namely T Aur, HR Del, DQ Her, and QU Vul, and the nova-like source CK Vul. These are used to construct models of their nebular remnants using the morphokinematic modelling tool SHAPE to reveal their 3D shape. All th…
Polarization, polarizing efficiency, and grain alignment towards the direction of the cluster NGC 2345
Hoang, Thiem; Pandey, Jeewan C.; Singh, Sadhana
We have investigated the grain alignment and dust properties towards the direction of the cluster NGC 2345 using the multiband optical polarimetric observations. For the majority of the stars, the observed polarization is found to be due to the interstellar medium with average values of maximum polarization and wavelength corresponding to it as 1.…
The transient ultraluminous X-ray source, ULX-4, in M51
Akyuz, A.; Aksaker, N.; Avdan, S. +6 more
We present the results of a temporal and spectral analysis of the transient source ULX-4 in the galaxy M51. The data used were drawn from Chandra, XMM-Newton, and Swift-XRT archives, spanning the years 2000-2019.. The X-ray flux of the source is seen to vary by two orders of magnitudes within a month but a short-term variability was not observed o…
The cycle of metals in the infalling elliptical galaxy NGC 1404
Simionescu, A.; Mernier, F.; Pinto, C. +6 more
Hot atmospheres pervading galaxy clusters, groups, and early-type galaxies are rich in metals, produced during epochs and diffused via processes that are still to be determined. While this enrichment has been routinely investigated in clusters, metals in lower mass systems are more challenging to probe with standard X-ray exposures and spectroscop…
APOGEE detection of N-rich stars in the tidal tails of Palomar 5
Cohen, Roger E.; Majewski, Steven R.; Horta, Danny +15 more
Recent results from chemical tagging studies using Apache Point Observatory Galactic Evolution Experiment data suggest a strong link between the chemical abundance patterns of stars found within globular clusters (GC), and chemically peculiar populations in the Galactic halo field. In this paper, we analyse the chemical compositions of stars withi…
The star formation rates of QSOs
Andreani, P.; Ivison, R. J.; Clements, D. L. +13 more
We examine the far-infrared (FIR) properties of a sample of 5391 optically selected QSOs in the 0.5 < z < 2.65 redshift range down to log [νLν, 2500(erg s-1)] > 44.7, using SPIRE data from Herschel-ATLAS. We split the sample in a grid of 74 luminosity-redshift bins and compute the average optical-IR spectral energy d…
High resolution X-ray spectroscopy of V4641 Sgr during its 2020 outburst
Heinke, C. O.; Miller, J. M.; Gandhi, P. +7 more
We observed the Galactic black hole X-ray binary V4641 Sgr with the high resolution transmission gratings on Chandra during the source's 2020 outburst. Over two epochs of Chandra gratings observations, we see numerous highly ionized metal lines, superimposed on a hot, disc-dominated X-ray continuum. The measured inner disc temperatures and luminos…
SHARP - VIII. J0924+0219 lens mass distribution and time-delay prediction through adaptive-optics imaging
Treu, Tommaso; Lagattuta, David J.; Fassnacht, Christopher D. +6 more
Strongly lensed quasars can provide measurements of the Hubble constant (H0) independent of any other methods. One of the key ingredients is exquisite high-resolution imaging data, such as Hubble Space Telescope (HST) imaging and adaptive-optics (AO) imaging from ground-based telescopes, which provide strong constraints on the mass dist…