Search Publications
The distances to Novae as seen by Gaia
Schaefer, Bradley E.
The Gaia spacecraft has just released a large set of parallaxes, including 41 novae for which the fractional error is <30 per cent. I have used these to evaluate the accuracy and bias of the many prior methods for getting nova distances. The best of the prior methods is the geometrical parallaxes from Hubble Space Telescope for just four novae,…
New constraints on time-dependent variations of fundamental constants using Planck data
Chluba, Jens; Hart, Luke
Observations of the cosmic microwave background (CMB) today allow us to answer detailed questions about the properties of our Universe, targeting both standard and non-standard physics. In this paper, we study the effects of varying fundamental constants (i.e. the fine-structure constant, αEM, and electron rest mass, me) arou…
The nature of luminous Ly α emitters at z ∼ 2-3: maximal dust-poor starbursts and highly ionizing AGN
Smail, Ian; Sobral, David; Mobasher, Bahram +8 more
Deep narrow-band surveys have revealed a large population of faint Ly α emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources ({L}_{Lyα } ≳ 10^{42.7} erg s-1; L_{Lyα }≳ L^*_{Lyα }). Here we present the spectroscopic follow-up of 21 luminous LAEs at z ∼ 2-3 found with panoramic narrow-ban…
The XMM-SERVS survey: new XMM-Newton point-source catalogue for the XMM-LSS field
Smail, I.; Kelson, D. D.; Häußler, B. +28 more
We present an X-ray point-source catalogue from the XMM-Large Scale Structure (XMM-LSS) survey region, one of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields. We target the XMM-LSS region with 1.3 Ms of new XMM-Newton AO-15 observations, transforming the archival X-ray coverage in this region into a 5.3 deg2
Ultrafast outflow in tidal disruption event ASASSN-14li
Reynolds, C. S.; Kara, E.; Kallman, T. +1 more
At only 90 Mpc, ASASSN-14li is one of the nearest tidal disruption events (TDE) ever discovered, and because of this, it has been observed by several observatories at many wavelengths. In this paper, we present new results on archival XMM-Newton observations, three of which were taken at early times (within 40 d of the discovery), and three of whi…
Physical properties and H-ionizing-photon production rates of extreme nearby star-forming regions
Feltre, Anna; Charlot, Stéphane; Chevallard, Jacopo +7 more
Measurements of the galaxy UV luminosity function at z ≳ 6 suggest that young stars hosted in low-mass star-forming galaxies produced the bulk of hydrogen-ionizing photons necessary to reionize the intergalactic medium (IGM) by redshift z ∼ 6. Whether star-forming galaxies dominated cosmic reionization, however, also depends on their stellar popul…
Connecting young star clusters to CO molecular gas in NGC 7793 with ALMA-LEGUS
Gallagher, J. S.; Dale, D. A.; Calzetti, D. +20 more
We present an investigation of the relationship between giant molecular cloud (GMC) properties and the associated stellar clusters in the nearby flocculent galaxy NGC 7793. We combine the star cluster catalogue from the HST LEGUS (Legacy ExtraGalactic UV Survey) programme with the 15 pc resolution ALMA CO(2-1) observations. We find a strong spatia…
The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae
Belokurov, V.; Koposov, S. E.; Iorio, G. +3 more
We exploit the first Gaia data release to study the properties of the Galactic stellar halo as traced by RR Lyrae. We demonstrate that it is possible to select a pure sample of RR Lyrae using only photometric information available in the Gaia+2MASS catalogue. The final sample contains about 21 600 RR Lyrae covering an unprecedented fraction ( ∼ 60…
Imprints of cosmic rays in multifrequency observations of the interstellar emission
Orlando, E.
Ever since the discovery of cosmic rays (CRs), significant advancements have been made in modelling their propagation in the Galaxy and in the Heliosphere. However, propagation models suffer from degeneracy of many parameters. To complicate the picture, the precision of recent data have started challenging existing models. To tackle these issues, …
An automatic taxonomy of galaxy morphology using unsupervised machine learning
Geach, James E.; Hocking, Alex; Sun, Yi +1 more
We present an unsupervised machine learning technique that automatically segments and labels galaxies in astronomical imaging surveys using only pixel data. Distinct from previous unsupervised machine learning approaches used in astronomy we use no pre-selection or pre-filtering of target galaxy type to identify galaxies that are similar. We demon…