V. A. Fawcett
A5041983019- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Cosmology and Gravitation Theories
- CCD and CMOS Imaging Sensors
- Remote Sensing in Agriculture
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
Newcastle University
2023-2025
Newcastle upon Tyne Hospital
2024
Durham University
2020-2023
University of Warwick
2022
The Dark Energy Spectroscopic Instrument (DESI) has embarked on an ambitious five-year survey to explore the nature of dark energy with spectroscopy 40 million galaxies and quasars. DESI will determine precise redshifts employ Baryon Acoustic Oscillation method measure distances from nearby universe z > 3.5, as well growth structure probe potential modifications general relativity. In this paper we describe significant instrumentation developed for survey. new includes a wide-field, 3.2-deg...
Abstract The Dark Energy Spectroscopic Instrument (DESI) completed its 5 month Survey Validation in 2021 May. Spectra of stellar and extragalactic targets from constitute the first major data sample DESI survey. This paper describes public release those spectra, catalogs derived properties, intermediate products. In total, includes good-quality spectral information 466,447 objects targeted as part Milky Way Survey, 428,758 Bright Galaxy 227,318 Luminous Red sample, 437,664 Emission Line...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...
The Dark Energy Spectroscopic Instrument (DESI) completed its five-month Survey Validation in May 2021. Spectra of stellar and extragalactic targets from constitute the first major data sample DESI survey. This paper describes public release those spectra, catalogs derived properties, intermediate products. In total, includes good-quality spectral information 466,447 objects targeted as part Milky Way Survey, 428,758 Bright Galaxy 227,318 Luminous Red sample, 437,664 Emission Line 76,079...
Abstract A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) optical spectroscopic data to quantify metrics. In this paper we present results from VI quasar using deep coadded SV spectra. We show that majority (≈70%) main-survey targets are spectroscopically confirmed as quasars, with ≈16% galaxies, ≈6% stars, and ≈8% low-quality spectra lacking reliable features. nonnegligible fraction quasars misidentified by...
Abstract Changing-look active galactic nuclei (CL AGNs) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines (BELs), associated with a transient timescale (about 100 ∼ 5000 days) that is much shorter than predicted traditional accretion disk models. We carry out systematic CL AGN search crossmatching spectra coming from Dark Energy Spectroscopic Instrument and Sloan Digital Sky Survey. Following previous studies, we identify AGNs based on...
Abstract The Dark Energy Spectroscopic Instrument (DESI) cosmology survey includes a Bright Galaxy Survey (BGS), which will yield spectra for over 10 million bright galaxies ( r < 20.2 AB mag). resulting sample be valuable both cosmological and astrophysical studies. However, the star/galaxy separation criterion implemented in nominal BGS target selection algorithm excludes quasar host addition to bona fide stars. While this excluded population is comparatively rare (∼3–4 per square...
Abstract Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a fourfold increase in number known quasars. High-accuracy classification is essential tighten constraints on cosmological parameters measured at highest redshifts DESI observes ( z > 2.0). We present spectral templates for identification and redshift estimation quasars Year 1 data release. The are comprised two eigenspectra sets, trained from Sloan Digital Sky Survey. sets...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...
Fundamental differences in the radio properties of red quasars (QSOs), as compared to blue QSOs, have been recently discovered, positioning them a potential key population evolution galaxies and black holes across cosmic time. To elucidate their nature, we exploited rich compilation photometry spectroscopic data model spectral energy distributions (SEDs) from UV FIR characterise emission-line properties. Following systematic comparison approach, infer AGN accretion, obscuration, host galaxy...
ABSTRACT We have recently used the Faint Images of Radio Sky at Twenty-centimeters (FIRST) survey to show that red quasars fundamentally different radio properties typical blue quasars: a significant (factor ≈3) enhancement in radio-detection fraction, which arises from systems around radio-quiet threshold with compact (&lt;5 arcsec) morphologies. To gain greater insight into these physical differences, here we use DR14 Sloan Digital Survey (SDSS) and more sensitive, higher resolution...
Abstract We present findings of the detection Magnesium II (Mg ii , λ = 2796, 2803 Å) absorbers from early data release Dark Energy Spectroscopic Instrument (DESI). DESI is projected to obtain spectroscopy approximately 3 million quasars (QSOs), which over 99% are anticipated be at redshifts greater than z > 0.3, such that would able observe an associated or intervening Mg absorber illuminated by background QSO. have developed autonomous supplementary spectral pipeline detects these...
ABSTRACT We have recently found fundamental differences in the radio properties of red quasars when compared to typical blue quasars. In this paper, we use data from X-shooter spectrograph on Very Large Telescope, providing spectral coverage ∼3000–$25\,000\,$ Å, a sample 40 and luminous at 1.45 &lt; z 1.65 explore connections between radio, emission-line, accretion-disc properties. fit various dust-extinction curves find that dust reddening can fully explain observed colours for majority...
Abstract Recent studies have found a striking positive correlation between the amount of dust obscuration and enhanced radio emission in quasi-stellar objects (QSOs). However, what causes this connection remains unclear. In paper we analyse uGMRT Band-3 (400 MHz) Band-4 (650 data sample 38 1.0 &lt; z 1.5 QSOs with existing high-resolution 0${_{.}^{\prime\prime}}$2 e-MERLIN 1.4 GHz imaging. combination archival data, constructed sensitive 4–5 band SEDs across 0.144–3 to further...
Red quasi-stellar objects (QSOs) are a subset of the luminous end cosmic population active galactic nuclei (AGN), most which reddened by intervening dust along line-of-sight towards their central engines. In recent work from our team, we developed systematic technique to select red QSOs Sloan Digital Sky Survey (SDSS), and demonstrated that they have distinctive radio properties using Faint Images Radio at Twenty centimeters (FIRST) survey. Here expand study low-frequency data LOFAR...
The origin of radio emission in different populations radio-quiet quasars is relatively unknown, but recent work has uncovered various drivers increased radio-detection fraction. In this work, we pull together three known factors: optical colour ($g-i$), \CIV Distance (a proxy for $L/L_{Edd}$) and whether or not the quasar contains broad absorption lines (BALQSOs) which signify an outflow. We use SDSS DR14 spectra along with LOFAR Two Metre Sky Survey Data Release 2 find that each these...
ABSTRACT We present the first eight months of data from our secondary target programme within ongoing Dark Energy Spectroscopic Instrument (DESI) survey. Our uses a mid-infrared and optical colour selection to preferentially dust-reddened quasi-stellar objects (QSOs) that would have otherwise been missed by nominal DESI QSO selection. So far, we obtained spectra for 3038 candidates, which ∼70 per cent high-quality (those with robust redshifts) are visually confirmed be Type 1 QSOs,...
ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the quasar population with colours consistent reddening due to intervening dust. Recent work has demonstrated that red QSOs show special radio properties fundamentally distinguish them from normal blue QSOs, specifically higher incidence low-power emission (1.4 GHz luminosities L1.4 ≈ 1025–1027 W Hz−1) is physically compact when imaged by arcsecond-resolution surveys such as FIRST. In this work, we present e-MERLIN imaging set...
Abstract We present a catalog of hard X-ray serendipitous sources detected in the first 80 months observations by Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR survey month (NSS80) has an unprecedented ∼62 Ms effective exposure time over 894 unique fields (a factor 3 increase 40 catalog, NSS40), with areal coverage ∼36 deg 2 , larger than all extragalactic surveys. NSS80 provides 1274 3−24 keV band (822 new detections compared to previous NSS40). Approximately 76% have...
We present the identification of changing-look active galactic nuclei (CL-AGNs) from Dark Energy Spectroscopic Instrument First Data Release and Sloan Digital Sky Survey 16 at z \leq 0.9. To confirm CL-AGNs, we utilize spectral flux calibration assessment via an [O\,{\sc iii}]-based calibration, pseudo-photometry examination, visual inspection. This rigorous selection process allows us to compile a statistical catalog 561 encompassing 527 $\rm H\beta$, 149$\rm H\alpha$, 129 Mg II CL...
The observed optical colors of quasars are generally interpreted in one two frameworks: unified models which attribute color to random orientation the accretion disk along line-of-sight, and evolutionary invoke connections between quasar systems their environments. We test these schema by probing dark matter halo environments optically-selected as a function $g-i$ measuring two-point correlation functions $\sim$ 0.34 million eBOSS well gravitational deflection cosmic microwave background...
ABSTRACT Broad absorption line quasars (BALQSOs) show strong signatures of powerful outflows, with the potential to alter cosmic history their host galaxies. These are only seen in ∼10 per cent optically selected quasars, although fraction significantly increases IR and radio samples. A proven physical explanation for this observed has yet be found, along a determination why at wavelengths. We present largest sample matched BALQSOs using LOFAR Two-metre Sky Survey Data Release 2 employ it...
We present a comprehensive study of the physical origin radio emission in optical quasars at redshifts z < 2.5. focus particularly on associations between compact emission, dust reddening, and outflows identified our earlier work. Leveraging deepest low-frequency data available to date (LoTSS Deep DR1), we achieve detection fractions up 94%, demonstrating virtual ubiquity quasars, continuous distribution loudness. Through analysis properties, combined with spectral energy modeling...
A non-negligible fraction of quasars are red at optical wavelengths, indicating (in the majority cases) that accretion disc is obscured by a column dust which extinguishes shorter-wavelength blue emission. In this paper, we summarize recent work our group, where find fundamental differences in radio properties SDSS optically-selected quasars. We also present new analyses, using consistent color-selected quasar parent sample matched to four surveys (FIRST, VLA Stripe 82, COSMOS 3 GHz, and...
ABSTRACT We present an analysis of XMM–Newton observations four stars in the young (670 Myr) open cluster Praesepe. The planets hosted by these all lie close radius–period space to valley and/or Neptunian desert, two features that photoevaporation X-ray and extreme ultraviolet (EUV) photons could be driving. Although are no longer saturated regime, strong irradiation is still ongoing. Based on EUV time evolution slopes, we derived a previous paper, cases, two-thirds their come. compare light...