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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.

Andrew Bunker

Professor of Astrophysics

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Galaxy formation and evolution
Andy.Bunker@physics.ox.ac.uk
Telephone: 01865 (2)83126
Denys Wilkinson Building, room 702
  • About
  • Publications

Author Correction: A small and vigorous black hole in the early Universe

Nature Springer Nature 630:8015 (2024) e2-e2

Authors:

Roberto Maiolino, Jan Scholtz, Joris Witstok, Stefano Carniani, Francesco D’Eugenio, Anna de Graaff, Hannah Übler, Sandro Tacchella, Emma Curtis-Lake, Santiago Arribas, Andrew Bunker, Stéphane Charlot, Jacopo Chevallard, Mirko Curti, Tobias J Looser, Michael V Maseda, Timothy D Rawle, Bruno Rodríguez del Pino, Chris J Willott, Eiichi Egami, Daniel J Eisenstein, Kevin N Hainline, Brant Robertson, Christina C Williams, Christopher NA Willmer, William M Baker, Kristan Boyett, Christa DeCoursey, Andrew C Fabian, Jakob M Helton, Zhiyuan Ji, Gareth C Jones, Nimisha Kumari, Nicolas Laporte, Erica J Nelson, Michele Perna, Lester Sandles, Irene Shivaei, Fengwu Sun
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The Galaxies Missed by Hubble and ALMA: The Contribution of Extremely Red Galaxies to the Cosmic Census at 3 < z < 8

The Astrophysical Journal American Astronomical Society 968:1 (2024) 34

Authors:

Christina C Williams, Stacey Alberts, Zhiyuan Ji, Kevin N Hainline, Jianwei Lyu, George Rieke, Ryan Endsley, Katherine A Suess, Fengwu Sun, Benjamin D Johnson, Michael Florian, Irene Shivaei, Wiphu Rujopakarn, William M Baker, Rachana Bhatawdekar, Kristan Boyett, Andrew J Bunker, Alex J Cameron, Stefano Carniani, Stephane Charlot, Emma Curtis-Lake, Christa DeCoursey, Anna de Graaff, Eiichi Egami, Aayush Saxena

Abstract:

Using deep JWST imaging from JADES, JEMS, and SMILES, we characterize optically faint and extremely red galaxies at z > 3 that were previously missing from galaxy census estimates. The data indicate the existence of abundant, dusty, and poststarburst-like galaxies down to 108 M ⊙, below the sensitivity limit of Spitzer and the Atacama Large Millimeter/submillimeter Array (ALMA). Modeling the NIRCam and Hubble Space Telescope (HST) photometry of these red sources can result in extremely high values for both stellar mass and star formation rate (SFR); however, including seven MIRI filters out to 21 μm results in decreased masses (median 0.6 dex for log10(M∗/M⊙) > 10) and SFRs (median 10× for SFR > 100 M ⊙ yr−1). At z > 6, our sample includes a high fraction of “little red dots” (LRDs; NIRCam-selected dust-reddened active galactic nucleus (AGN) candidates). We significantly measure older stellar populations in the LRDs out to rest-frame 3 μm (the stellar bump) and rule out a dominant contribution from hot dust emission, a signature of AGN contamination to stellar population measurements. This allows us to measure their contribution to the cosmic census at z > 3, below the typical detection limits of ALMA (L IR < 1012 L ⊙). We find that these sources, which are overwhelmingly missed by HST and ALMA, could effectively double the obscured fraction of the star formation rate density at 4 < z < 6 compared to some estimates, showing that prior to JWST, the obscured contribution from fainter sources could be underestimated. Finally, we identify five sources with evidence for Balmer breaks and high stellar masses at 5.5 < z < 7.7. While spectroscopy is required to determine their nature, we discuss possible measurement systematics to explore with future data.
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What Is the Nature of Little Red Dots and what Is Not, MIRI SMILES Edition

The Astrophysical Journal American Astronomical Society 968:1 (2024) 4

Authors:

Pablo G Pérez-González, Guillermo Barro, George H Rieke, Jianwei Lyu, Marcia Rieke, Stacey Alberts, Christina C Williams, Kevin Hainline, Fengwu Sun, Dávid Puskás, Marianna Annunziatella, William M Baker, Andrew J Bunker, Eiichi Egami, Zhiyuan Ji, Benjamin D Johnson, Brant Robertson, Bruno Rodríguez Del Pino, Wiphu Rujopakarn, Irene Shivaei, Sandro Tacchella, Christopher NA Willmer, Chris Willott

Abstract:

We study 31 little red dots (LRD) detected by JADES/NIRCam and covered by the SMILES/MIRI survey, of which ∼70% are detected in the two bluest MIRI bands and 40% in redder MIRI filters. The median/quartiles redshifts are z=6.95.97.7 (55% spectroscopic). The spectral slopes flatten in the rest-frame near-infrared, consistent with a 1.6 μm stellar bump but bluer than direct pure emission from active galactic nuclei (AGN) tori. The apparent dominance of stellar emission at these wavelengths for many LRDs expedites stellar mass estimation: the median/quartiles are logM⋆/M⊙=9.49.19.7 . The number density of LRDs is 10−4.0±0.1 Mpc−3, accounting for 14% ± 3% of the global population of galaxies with similar redshifts and masses. The rest-frame near-/mid-infrared (2–4 μm) spectral slope reveals significant amounts of warm dust (bolometric attenuation ∼3–4 mag). Our spectral energy distribution modeling implies the presence of <0.4 kpc diameter knots, heated by either dust-enshrouded OB stars or an AGN producing a similar radiation field, obscured by A(V) > 10 mag. We find a wide variety in the nature of LRDs. However, the best-fitting models for many of them correspond to extremely intense and compact starburst galaxies with mass-weighted ages 5–10 Myr, very efficient in producing dust, with their global energy output dominated by the direct (in the flat rest-frame ultraviolet and optical spectral range) and dust-recycled emission from OB stars with some contribution from an obscured AGN (in the infrared).
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Lyα emission in galaxies at z ≃ 5−6: new insight from JWST into the statistical distributions of Lyα properties at the end of reionization

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 531:2 (2024) 2701-2730

Authors:

Mengtao Tang, Daniel P Stark, Richard S Ellis, Fengwu Sun, Michael Topping, Brant Robertson, Sandro Tacchella, Santiago Arribas, William M Baker, Rachana Bhatawdekar, Kristan Boyett, Andrew J Bunker, Stéphane Charlot, Zuyi Chen, Jacopo Chevallard, Gareth C Jones, Nimisha Kumari, Jianwei Lyu, Roberto Maiolino, Michael V Maseda, Aayush Saxena, Lily Whitler, Christina C Williams, Chris Willott, Joris Witstok
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5-25 $\mu$m Galaxy Number Counts from Deep JWST Data

(2024)

Authors:

Meredith A Stone, Stacey Alberts, George H Rieke, Andrew J Bunker, Jianwei Lyu, Pablo G Pérez-González, Irene Shivaei, Yongda Zhu
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