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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.

Dr Hengxing Pan

Visitor

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Cosmology
  • Galaxy formation and evolution
  • MeerKAT
  • The Square Kilometre Array (SKA)
hengxing.pan@physics.ox.ac.uk
  • About
  • Publications

New Constraints on the Evolution of the MH i−M⋆ Scaling Relation Combining CHILES and MIGHTEE-H i Data

The Astrophysical Journal American Astronomical Society 982:2 (2025) 82

Authors:

Alessandro Bianchetti, Francesco Sinigaglia, Giulia Rodighiero, Ed Elson, Mattia Vaccari, DJ Pisano, Nicholas Luber, Isabella Prandoni, Kelley Hess, Maarten Baes, Elizabeth AK Adams, Filippo M Maccagni, Alvio Renzini, Laura Bisigello, Min Yun, Emmanuel Momjian, Hansung B Gim, Hengxing Pan, Thomas A Oosterloo, Richard Dodson, Danielle Lucero, Bradley S Frank, Olivier Ilbert, Luke JM Davies, Ali A Khostovan, Mara Salvato
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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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Deep extragalactic H i survey of the COSMOS field with FAST

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 534:1 (2024) 202-214

Authors:

Hengxing Pan, Matt J Jarvis, Ming Zhu, Yin-Zhe Ma, Mario G Santos, Anastasia A Ponomareva, Ian Heywood, Yingjie Jing, Chen Xu, Ziming Liu, Yogesh Chandola, Yipeng Jing
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MIGHTEE-H i: deep spectral line observations of the COSMOS field

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 534:1 (2024) 76-96

Authors:

I Heywood, AA Ponomareva, N Maddox, MJ Jarvis, BS Frank, EAK Adams, M Baes, A Bianchetti, JD Collier, RP Deane, M Glowacki, SL Jung, H Pan, SHA Rajohnson, G Rodighiero, I Ruffa, MG Santos, F Sinigaglia, M Vaccari
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MIGHTEE-HI: HI galaxy properties in the large scale structure environment at z ∼ 0.37 from a stacking experiment

Monthly Notices of the Royal Astronomical Society Oxford University Press 529:4 (2024) 4192-4209

Authors:

Francesco Sinigaglia, Giulia Rodighiero, Ed Elson, Alessandro Bianchetti, Mattia Vaccari, Natasha Maddox, Anastasia A Ponomareva, Bradley S Frank, Matt J Jarvis, Barbara Catinella, Luca Cortese, Sambit Roychowdhury, Maarten Baes, Jordan D Collier, Olivier Ilbert, Ali A Khostovan, Sushma Kurapati, Hengxing Pan, Isabella Prandoni, Sambatriniaina HA Rajohnson, Mara Salvato, Srikrishna Sekhar, Gauri Sharma

Abstract:

We present the first measurement of HI mass of star-forming galaxies in different large scale structure environments from a blind survey at z ∼ 0.37. In particular, we carry out a spectral line stacking analysis considering 2875 spectra of colour-selected star-forming galaxies undetected in HI at 0.23 < z < 0.49 in the COSMOS field, extracted from the MIGHTEE-HI Early Science datacubes, acquired with the MeerKAT radio telescope. We stack galaxies belonging to different subsamples depending on three different definitions of large scale structure environment: local galaxy overdensity, position inside the host dark matter halo (central, satellite, or isolated), and cosmic web type (field, filament, or knot). We first stack the full star-forming galaxy sample and find a robust HI detection yielding an average galaxy HI mass of MHI = (8.12 ± 0.75) × 109 M⊙ at ∼11.8σ. Next, we investigate the different subsamples finding a negligible difference in MHI as a function of the galaxy overdensity. We report an HI excess compared to the full sample in satellite galaxies (MHI = (11.31 ± 1.22) × 109, at ∼10.2σ) and in filaments (MHI = (11.62 ± 0.90) × 109. Conversely, we report non-detections for the central and knot galaxies subsamples, which appear to be HI-deficient. We find the same qualitative results also when stacking in units of HI fraction (fHI). We conclude that the HI amount in star-forming galaxies at the studied redshifts correlates with the large scale structure environment.
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