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On the simultaneous modelling of dust and stellar populations for interpretation of galaxy properties
Stanway, Elizabeth R.; Carnall, Adam C.; Jones, Gareth T.
The physical properties of galaxies are encoded within their spectral energy distribution and require comparison with models to be extracted. These models must contain a synthetic stellar population and, where infrared data are to be used, also consider prescriptions for energy reprocessing and re-emission by dust. While many such models have been…
Hubble Space Telescope Imaging Reveals That SN 2015bh Is Much Fainter than Its Progenitor
Smith, Nathan; Strader, Jay; Sand, David J. +5 more
We present Hubble Space Telescope (HST) imaging of the site of SN 2015bh in the nearby spiral galaxy NGC 2770 taken between 2017 and 2019, nearly four years after the peak of the explosion. In 2017-2018, the transient fades steadily in optical filters before declining more slowly to F814W = -7.1 mag in 2019, ≈4 mag below the level of its eruptive …
Variable mass accretion and failed wind explain changing-look phenomena in NGC 1365
Stalin, C. S.; Hryniewicz, K.; Adhikari, T. P. +2 more
Changing-look active galactic nuclei (CLAGNs) show a complex nature in their X-ray spectral shape and line-of-sight column-density variation. The physical mechanisms responsible for these variations are unclear. Here, we study the spectral properties of a CLAGN, NGC 1365 using combined XMM-Newton and NuSTAR observations to understand the CL behavi…
The Close AGN Reference Survey (CARS). Tracing the circumnuclear star formation in the super-Eddington NLS1 Mrk 1044
Jahnke, K.; Gaspari, M.; Combes, F. +11 more
Context. The host galaxy conditions for rapid supermassive black hole growth are poorly understood. Narrow-line Seyfert 1 (NLS1) galaxies often exhibit high accretion rates and are hypothesized to be prototypes of active galactic nuclei (AGN) at an early stage of their evolution.
Aims: We present adaptive optics (AO) assisted VLT MUSE NFM obs…
Uniform Recalibration of Common Spectrophotometry Standard Stars onto the CALSPEC System Using the SuperNova Integral Field Spectrograph
Aldering, G.; Kim, A. G.; Kowalski, M. +35 more
We calibrate spectrophotometric optical spectra of 32 stars commonly used as standard stars, referenced to 14 stars already on the Hubble Space Telescope-based CALSPEC flux system. Observations of CALSPEC and non-CALSPEC stars were obtained with the SuperNova Integral Field Spectrograph over the wavelength range 3300-9400 Å as calibration for the …
An Exceptional Dimming Event for a Massive, Cool Supergiant in M51
Smith, Nathan; Strader, Jay; Sand, David J. +6 more
We present the discovery of an exceptional dimming event in a cool supergiant star in the Local Volume spiral M51. The star, dubbed M51-DS1, was found as part of a Hubble Space Telescope (HST) search for failed supernovae (SNe). The supergiant, which is plausibly associated with a very young (≲6 Myr) stellar population, showed clear variability (a…
A Systematic Exploration of Kilonova Candidates from Neutron Star Mergers during the Third Gravitational-wave Observing Run
Fong, W.; Sand, D. J.; Rastinejad, J. C. +9 more
We present a comprehensive analysis of 653 optical candidate counterparts reported during the third gravitational-wave (GW) observing run. Our sample concentrates on candidates from the 15 events (published in GWTC-2, GWTC-3, or not retracted on GraceDB) that had a >1% chance of including a neutron star in order to assess their viability as tru…
SN 1987A: Tracing the flux decline and spectral evolution through a comparison of SRG/eROSITA and XMM-Newton observations
Haberl, F.; Freyberg, M. J.; Maggi, P. +3 more
Context. SN 1987A is the supernova closest to us observed in the past four centuries. It provides the unique opportunity of witnessing the birth and evolution of a supernova remnant. Monitoring the source in X-rays provides insights into the physics of the shock, the X-ray emitting plasma, and the interaction of the shock with the structures in th…
How to search for mirror stars with Gaia
Matzner, Christopher D.; Curtin, David; Howe, Aaron +1 more
We show for the first time how to conduct a direct search for dark matter using Gaia observations. Its public astrometric data may contain the signals of mirror stars, exotic compact objects made of atomic dark matter with a tiny kinetic mixing between the dark and SM photon. Mirror stars capture small amounts of interstellar material in their cor…
Constraining the overcontact phase in massive binary evolution. II. Period stability of known O+O overcontact systems
Mahy, Laurent; Abdul-Masih, Michael; Marchant, Pablo +2 more
Context. Given that mergers are often invoked to explain many exotic phenomena in massive star evolution, understanding the evolutionary phase directly preceding a merger, the overcontact phase, is of crucial importance. Despite this, large uncertainties exist in our understanding of the evolution of massive overcontact binaries.
Aims: We aim…