Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
Black Hole

Lensing of space time around a black hole. At Oxford we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Prof. Matt Jarvis

Professor of Astrophysics

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Cosmology
  • Galaxy formation and evolution
  • Hintze Centre for Astrophysical Surveys
  • MeerKAT
  • Rubin-LSST
  • The Square Kilometre Array (SKA)
Matt.Jarvis@physics.ox.ac.uk
Telephone: 01865 (2)83654
Denys Wilkinson Building, room 703
  • About
  • Publications

The radio loudness of SDSS quasars from the LOFAR Two-metre Sky Survey: ubiquitous jet activity and constraints on star formation

Monthly Notices of the Royal Astronomical Society Royal Astronomical Society 506:4 (2021) 5888-5907

Authors:

C Macfarlane, Pn Best, J Sabater, G Gürkan, Matt Jarvis, Hja Röttgering, Rd Baldi, G Calistro Rivera, Kj Duncan, Lk Morabito, I Prandoni, E Retana-Montenegro

Abstract:

We examine the distribution of radio emission from ∼42 000 quasars from the Sloan Digital Sky Survey, as measured in the LOFAR Two-metre Sky Survey (LoTSS). We present a model of the radio luminosity distribution of the quasars that assumes that every quasar displays a superposition of two sources of radio emission: active galactic nuclei (jets) and star formation. Our two-component model provides an excellent match to the observed radio flux density distributions across a wide range of redshifts and quasar optical luminosities; this suggests that the jet-launching mechanism operates in all quasars but with different powering efficiency. The wide distribution of jet powers allows for a smooth transition between the ‘radio-quiet’ and ‘radio-loud’ quasar regimes, without need for any explicit bimodality. The best-fitting model parameters indicate that the star formation rate of quasar host galaxies correlates strongly with quasar luminosity and also increases with redshift at least out to z ∼ 2. For a model where star formation rate scales as Lαbol(1+z)β⁠, we find α = 0.47 ± 0.01 and β = 1.61 ± 0.05, in agreement with far-infrared studies. Quasars contribute ≈0.15 per cent of the cosmic star formation rate density at z = 0.5, rising to 0.4 per cent by z ∼ 2. The typical radio jet power is seen to increase with both increasing optical luminosity and black hole mass independently, but does not vary with redshift, suggesting intrinsic properties govern the production of the radio jets. We discuss the implications of these results for the triggering of quasar activity and the launching of jets.
More details from the publisher
Details from ORA
More details
More details

Deep Extragalactic VIsible Legacy Survey (DEVILS): consistent multiwavelength photometry for the DEVILS regions (COSMOS, XMMLSS, and ECDFS)

Monthly Notices of the Royal Astronomical Society Oxford University Press 506:1 (2021) 256-287

Authors:

Ljm Davies, Je Thorne, Asg Robotham, S Bellstedt, Sp Driver, Nj Adams, M Bilicki, Raa Bowler, M Bravo, L Cortese, C Foster, Mw Grootes, B Haussler, A Hashemizadeh, Bw Holwerda, P Hurley, Mj Jarvis, C Lidman, N Maddox, M Meyer, M Paolillo, S Phillipps, M Radovich, M Siudek, M Vaccari, Ra Windhorst

Abstract:

The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y < 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the PROFOUND image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 μm. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.
More details from the publisher
Details from ORA
More details

HELP: the Herschel Extragalactic Legacy Project

Monthly Notices of the Royal Astronomical Society Oxford University Press 507:1 (2021) 129-155

Authors:

R Shirley, K Duncan, Mc Campos Varillas, Pd Hurley, K Malek, Y Roehlly, Mwl Smith, H Aussel, T Bakx, V Buat, D Burgarella, N Christopher, S Duivenvoorden, S Eales, A Efstathiou, Ea Gonzalez Solares, M Griffin, M Jarvis, B Lo Faro, L Marchetti, I McCheyne, A Papadopoulos, K Penner, E Pons, M Prescott, E Rigby, H Rottgering, A Saxena, J Scudder, M Vaccari, L Wang, Sj Oliver

Abstract:

We present the Herschel Extragalactic Legacy Project (HELP). This project collates, curates, homogenizes, and creates derived data products for most of the premium multiwavelength extragalactic data sets. The sky boundaries for the first data release cover 1270 deg2 defined by the Herschel SPIRE extragalactic survey fields; notably the Herschel Multi-tiered Extragalactic Survey (HerMES) and the Herschel Atlas survey (H-ATLAS). Here, we describe the motivation and principal elements in the design of the project. Guiding principles are transparent or 'open' methodologies with care for reproducibility and identification of provenance. A key element of the design focuses around the homogenization of calibration, meta data, and the provision of information required to define the selection of the data for statistical analysis. We apply probabilistic methods that extract information directly from the images at long wavelengths, exploiting the prior information available at shorter wavelengths and providing full posterior distributions rather than maximum-likelihood estimates and associated uncertainties as in traditional catalogues. With this project definition paper, we provide full access to the first data release of HELP; Data Release 1 (DR1), including a monolithic map of the largest SPIRE extragalactic field at 385 deg2 and 18 million measurements of PACS and SPIRE fluxes. We also provide tools to access and analyse the full HELP data base. This new data set includes far-infrared photometry, photometric redshifts, and derived physical properties estimated from modelling the spectral energy distributions over the full HELP sky. All the software and data presented is publicly available.
More details from the publisher
Details from ORA
More details
More details

HI intensity mapping with the MIGHTEE survey: power spectrum estimates

Monthly Notices of the Royal Astronomical Society Oxford University Press 505:2 (2021) 2039-2050

Authors:

Sourabh Paul, Mario G Santos, Junaid Townsend, Matt J Jarvis, Natasha Maddox, Jordan D Collier, Bradley S Frank, Russ Taylor

Abstract:

Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large-scale structure of the Universe. In this paper, we demonstrate that using the 64-dish MeerKAT radio telescope as a connected interferometer, it is possible to make a statistical detection of H I in the post-reionization Universe. With the MIGHTEE (MeerKAT International GHz Tiered Extragalactic Exploration) survey project observing in the L-band (856 MHz < ν < 1712 MHz, z < 0.66), we can achieve the required sensitivity to measure the H I IM power spectrum on quasi-linear scales, which will provide an important complementarity to the single-dish IM MeerKAT observations. We present a purpose-built simulation pipeline that emulates the MIGHTEE observations and forecasts the constraints that can be achieved on the H I power spectrum at z = 0.27 for k > 0.3 Mpc−1 using the foreground avoidance method. We present the power spectrum estimates with the current simulation on the COSMOS field that includes contributions from H I, noise, and point-source models constructed from the observed MIGHTEE data. The results from our visibility-based pipeline are in qualitative agreement to the already available MIGHTEE data. This paper demonstrates that MeerKAT can achieve very high sensitivity to detect H I with the full MIGHTEE survey on quasi-linear scales (signal-to-noise ratio >7 at k = 0.49 Mpc−1⁠) that are instrumental in probing cosmological quantities such as the spectral index of fluctuation, constraints on warm dark matter, the quasi-linear redshift space distortions, and the measurement of the H I content of the Universe up to z ∼ 0.5.
More details from the publisher
Details from ORA
More details
More details

Low-frequency radio spectra of submillimetre galaxies in the Lockman Hole

Astronomy and Astrophysics European Southern Observatory 648 (2021) A14

Authors:

J Ramasawmy, Je Geach, Mj Hardcastle, Pn Best, M Bonato, M Bondi, G Calistro Rivera, Rk Cochrane, Je Conway, K Coppin, Kj Duncan, Js Dunlop, M Franco, C Garcia-Vergara, Matt Jarvis, R Kondapally, I McCheyne, I Prandoni, Hja Rottgering, Djb Smith, C Tasse, L Wang

Abstract:

Aims. We investigate the radio properties of a sample of 850 μm-selected sources from the SCUBA-2 Cosmology Legacy Survey (S2CLS) using new deep, low-frequency radio imaging of the Lockman Hole field from the Low Frequency Array. This sample consists of 53 sources, 41 of which are detected at >5σ at 150 MHz.
Methods. Combining these data with additional observations at 324 MHz, 610 MHz, and 1.4 GHz from the Giant Metrewave Radio Telescope and the Jansky Very Large Array, we find a variety of radio spectral shapes and luminosities (L1.4 GHz ranging from ~4 × 1023−1 × 1025) within our sample despite their similarly bright submillimetre flux densities (>4 mJy). We characterise their spectral shapes in terms of multi-band radio spectral indices. Finding strong spectral flattening at low frequencies in ~20% of sources, we investigate the differences between sources with extremely flat low-frequency spectra and those with ‘normal’ radio spectral indices (α > −0.25).
Results. As there are no other statistically significant differences between the two subgroups of our sample as split by the radio spectral index, we suggest that any differences are undetectable in galaxy-averaged properties that we can observe with our unresolved images, and likely relate to galaxy properties that we cannot resolve, on scales ≲1 kpc. We attribute the observed spectral flattening in the radio to free–free absorption, proposing that those sources with significant low-frequency spectral flattening have a clumpy distribution of star-forming gas. We estimate an average spatial extent of absorbing material of at most several hundred parsecs to produce the levels of absorption observed in the radio spectra. This estimate is consistent with the highest-resolution observations of submillimetre galaxies in the literature, which find examples of non-uniform dust distributions on scales of ~100 pc, with evidence for clumps and knots in the interstellar medium. Additionally, we find two bright (>6 mJy) S2CLS sources undetected at all other wavelengths. We speculate that these objects may be very high redshift sources, likely residing at z > 4.
More details from the publisher
Details from ORA
More details

Pagination

  • First page First
  • Previous page Prev
  • …
  • Page 10
  • Page 11
  • Page 12
  • Page 13
  • Current page 14
  • Page 15
  • Page 16
  • Page 17
  • Page 18
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet