Search Publications
Improving the selection of changing-look AGNs through multiwavelength photometric variability
Stern, D.; Salvato, M.; Merloni, A. +13 more
We present second epoch optical spectra for 30 changing-look (CL) candidates found by searching for Type-1 optical variability in a sample of active galactic nuclei (AGNs) spectroscopically classified as Type 2. We use a random-forest-based light-curve classifier and spectroscopic follow-up, confirming 50 per cent of candidates as turning-on CLs. …
Low-ionization structures in planetary nebulae - II. Densities, temperatures, abundances, and excitation of six PNe
Gonçalves, Denise R.; Akras, Stavros; Mari, M. Belén
Here we present the spatially resolved study of six Galactic planetary nebulae (PNe), namely IC 4593, Hen 2-186, Hen 2-429, NGC 3918, NGC 6543, and NGC 6905, from intermediate-resolution spectra of the 2.5 m Isaac Newton Telescope and the 1.54 m Danish telescope. The physical conditions (electron densities, Ne, and temperatures, Te…
Revised orbits of the two nearest Jupiters
Butler, R. Paul; Vogt, Steven S.; Holden, Bradford +2 more
With its near-to-mid-infrared high-contrast imaging capabilities, JWST is ushering us into a golden age of directly imaging Jupiter-like planets. As the two closest cold Jupiters, ɛ Ind A b and ɛ Eridani b have sufficiently wide orbits and adequate infrared emissions to be detected by JWST. To detect more Jupiter-like planets for direct imaging, w…
Testing the evolutionary pathways of galaxies and their supermassive black holes and the impact of feedback from active galactic nuclei via large multiwavelength data sets
Mountrichas, George; Shankar, Francesco
It is still a matter of intense debate how supermassive black holes (SMBHs) grow and the role played by feedback from active galactic nuclei (AGN) in the coevolution of SMBHs and galaxies. To test the coevolution proposed by theoretical models, we compile a large AGN sample of 5639 X-ray detected AGN, over a wide redshift range, spanning nearly th…
A T-dwarf candidate from JWST early release NIRCam data
Hashimoto, Tetsuya; Goto, Tomotsugu; Kim, Seong Jin +6 more
We present a distant T-type brown dwarf candidate at ≈2.55 kpc discovered in the Cosmic Evolution Early Release Science (CEERS) fields by JWST NIRCam. In addition to the superb sensitivity, we utilized seven filters from JWST in near-infrared and thus is advantageous in finding faint, previously unseen brown dwarfs. From the model spectra in new J…
Improved radius determinations for the transiting brown dwarf population in the era of Gaia and TESS
Carmichael, Theron W.
I report updates to the substellar mass-radius diagram for 11 transiting brown dwarfs (BDs) and low-mass stars published before the third data release from the Gaia mission (Gaia DR3). I re-analyse these transiting BD systems whose physical parameters were published between 2008 and 2019 and find that when using the parallax measurements from Gaia…
MUSE-ALMA Haloes XI: gas flows in the circumgalactic medium
Kacprzak, Glenn G.; Nelson, Dylan; Kulkarni, Varsha P. +12 more
The flow of gas into and out of galaxies leaves traces in the circumgalactic medium which can then be studied using absorption lines towards background quasars. We analyse 27 ${{\log [N({\textrm {H}}\, {\small {I}})/\rm {cm}^{-2}]}} > 18.0$ H I absorbers at z = 0.2 to 1.4 from the MUSE-ALMA Haloes survey with at least one galaxy counterpart wit…
Measuring Galactic dark matter through unsupervised machine learning
Lim, Sung Hak; Buckley, Matthew R.; Shih, David +1 more
Measuring the density profile of dark matter in the Solar neighbourhood has important implications for both dark matter theory and experiment. In this work, we apply autoregressive flows to stars from a realistic simulation of a Milky Way-type galaxy to learn - in an unsupervised way - the stellar phase space density and its derivatives. With thes…
Stellar classification with convolutional neural networks and photometric images: a new catalogue of 50 million SDSS stars without spectra
Luo, A. -Li; Kong, Xiao; Shi, Jing-Hang +3 more
Stellar classification is a central topic in astronomical research that relies mostly on the use of spectra. However, with the development of large sky surveys, spectra are becoming increasingly scarce compared to photometric images. Numerous observed stars lack spectral types. In Sloan Digital Sky Survey (SDSS), there are more than hundreds of mi…
Spectroscopic follow-up of black hole and neutron star candidates in ellipsoidal variables from Gaia DR3
El-Badry, Kareem; Nagarajan, Pranav; Rodriguez, Antonio C. +2 more
We present multi-epoch spectroscopic follow-up of a sample of ellipsoidal variables selected from Gaia Data Release 3 (DR3) as candidates for hosting quiescent black holes (BHs) and neutron stars (NSs). Our targets were identified as BH/NS candidates because their optical light curves - when interpreted with models that attribute variability to ti…