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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

Hi intensity mapping with the MIGHTEE Survey: first results of the Hi power spectrum

Monthly Notices of the Royal Astronomical Society Oxford University Press 541:1 (2025) 476-493

Authors:

Aishrila Mazumder, Laura Wolz, Zhaoting Chen, Sourabh Paul, Mario G Santos, Matt Jarvis, Junaid Townsend, Srikrishna Sekhar, Russ Taylor

Abstract:

We present the first results of the H i intensity mapping power spectrum analysis with the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) survey. We use data covering 4 square degrees in the COSMOS field using a frequency range of 962.5–1008.42 MHz, equivalent to H i emission in . The data consist of 15 pointings with a total of 94.2 h on-source. We verify the suitability of the MIGHTEE data for H i intensity mapping by testing for residual systematics across frequency, baselines, and pointings. We also vary the window used for H i signal measurements and find no significant improvement using stringent Fourier mode cuts. We compute the H i power spectrum at scales in autocorrelation as well as cross-correlation between observational scans using power spectrum domain averaging for pointings. We report consistent upper limits of 29.8 mK Mpc from the 2 cross-correlation measurements and 25.82 mK Mpc from autocorrelation at 2 Mpc.The low signal-to-noise ratio in this data potentially limits our ability to identify residual systematics, which will be addressed in the future by incorporating more data in the analysis.
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On the relationship between the cosmic web and the alignment of galaxies and AGN jets

Monthly Notices of the Royal Astronomical Society Oxford University Press 539:3 (2025) 2362-2379

Authors:

S Lyla Jung, IH Whittam, MJ Jarvis, CL Hale, MN Tudorache, T Yasin

Abstract:

The impact of active galactic nuclei (AGNs) on the evolution of galaxies explains the steep decrease in the number density of the most massive galaxies in the Universe. However, the fuelling of the AGN and the efficiency of this feedback largely depend on their environment. We use data from the Low Frequency Array Two-metre Sky Survey Data Release 2 (DR2), the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys, and the Sloan Digital Sky Survey DR12 to make the first study of the orientations of radio jets and their optical counterpart in relation to the cosmic web environment. We find that close to filaments (), galaxies tend to have their optical major axes aligned with the nearest filaments. On the other hand, radio jets, which are generally aligned perpendicularly to the optical major axis of the host galaxy, show more randomized orientations with respect to host galaxies within of filaments. These results support the scenario that massive galaxies in cosmic filaments grow by numerous mergers directed along the orientation of the filaments while experiencing chaotic accretion of gas on to the central black hole. The AGN-driven jets consequently have a strong impact preferentially along the minor axes of dark matter haloes within filaments. We discuss the implications of these results for large-scale radio jet alignments, intrinsic alignments between galaxies, and the azimuthal anisotropy of the distribution of circumgalactic medium and anisotropic quenching.
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Looking at the Distant Universe with the MeerKAT Array: The H i Mass Function in the Local Universe

Astrophysical Journal American Astronomical Society 981:2 (2025) 208

Authors:

Amir Kazemi-Moridani, Andrew J Baker, Marc Verheijen, Eric Gawiser, Sarah-Louise Blyth, Danail Obreschkow, Laurent Chemin, Jordan D Collier, Kyle W Cook, Jacinta Delhaize, Ed Elson, Bradley S Frank, Marcin Glowacki, Kelley M Hess, Benne W Holwerda, Zackary L Hutchens, Matt J Jarvis, Melanie Kaasinen, Sphesihle Makhathini, Abhisek Mohapatra, Hengxing Pan, Anja C Schröder, Leyya Stockenstroom, Mattia Vaccari

Abstract:

We present measurements of the neutral atomic hydrogen (H i) mass function (HiMF) and cosmic H i density (ΩH I) at 0 ≤ z ≤ 0.088 from the Looking at the Distant Universe with MeerKAT Array (LADUMA) survey. Using LADUMA Data Release 1 (DR1), we analyze the HiMF via a new “recovery matrix” method that we benchmark against a more traditional modified maximum likelihood (MML) method. Our analysis, which implements a forward modeling approach, corrects for survey incompleteness and uses extensive synthetic source injections to ensure robust estimates of the HiMF parameters and their associated uncertainties. This new method tracks the recovery of sources in mass bins different from those in which they were injected and incorporates a Poisson likelihood in the forward modeling process, allowing it to correctly handle uncertainties in bins with few or no detections. The application of our analysis to a high-purity subsample of the LADUMA DR1 spectral line catalog in turn mitigates any possible biases that could result from the inconsistent treatment of synthetic and real sources. For the surveyed redshift range, the recovered Schechter function normalization, low-mass slope, and “knee” mass are ϕ*=3.56−1.92+0.97×10−3 Mpc−3 dex−1, α=−1.18−0.19+0.08 , and log(M*/M⊙)=10.01−0.12+0.31 , respectively, which together imply a comoving cosmic H i density of ΩHI=3.09−0.47+0.65×10−4 . Our results show consistency between recovery matrix and MML methods and with previous low-redshift studies, giving confidence that the cosmic volume probed by LADUMA, even at low redshifts, is not an outlier in terms of its H i content.
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MIGHTEE: Exploring the relationship between spectral index, redshift and radio luminosity

Monthly Notices of the Royal Astronomical Society (2025) staf209

Authors:

Siddhant Pinjarkar, Martin J Hardcastle, Dharam V Lal, Daniel JB Smith, José Afonso, Davi Barbosa, Catherine L Hale, Matt J Jarvis, Sthabile Kolwa, Eric Murphy, Mattia Vaccari, Imogen H Whittam
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The Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX) Active Galactic Nuclei Catalog: The Fourth Data Release

The Astrophysical Journal: Supplement Series American Astronomical Society 276:2 (2025) 72

Authors:

Chenxu Liu, Karl Gebhardt, Erin Mentuch Cooper, Dustin Davis, Donald P Schneider, Matt J Jarvis, Daniel J Farrow, Steven L Finkelstein, Óscar A Chávez Ortiz

Abstract:

We present the active galactic nuclei (AGN) catalog from the fourth data release (HDR4) of the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). HETDEX is an untargeted spectroscopic survey. HDR4 contains 345,874 Integral Field Unit observations from 2017 January to 2023 August covering an effective area of 62.9 deg2. With no imaging preselection, our spectroscopic confirmed AGN sample includes low-luminosity AGN, narrow-line AGN, and/or red AGN down to g ∼ 25. This catalog has 15,940 AGN across the redshifts of z = 0.1 ∼ 4.6, giving a raw AGN number density of 253.4 deg−2. Among them, 10,499 (66%) have redshifts either confirmed by line pairs or matched to the Sloan Digital Sky Survey Quasar Catalog. For the remaining 5441 AGN, 2083 are single broad-line AGN candidates, while the remaining 3358 are single intermediate broad-line (full width at half-maximum, FWHM ∼1200 km s−1) AGN candidates. A total of 4060 (39%) of the 10,499 redshift-confirmed AGN have emission-line regions 3σ more extended than the image quality, which could be strong outflows blowing into the outskirts of the host galaxies or ionized intergalactic medium.
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