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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 Chris Lintott

Professor of Astrophysics and Citizen Science Lead

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Zooniverse
  • Beecroft Institute for Particle Astrophysics and Cosmology
  • Rubin-LSST
chris.lintott@physics.ox.ac.uk
Telephone: 01865 (2)73638
Denys Wilkinson Building, room 532C
www.zooniverse.org
orcid.org/0000-0001-5578-359X
  • About
  • Citizen science
  • Group alumni
  • Publications

Zooniverse labs

Zooniverse lab
Build your own Zooniverse project

The Zooniverse lab lets anyone build their own citizen science project

Zooniverse Lab

Supermassive black holes in disk-dominated galaxies outgrow their bulges and co-evolve with their host galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 470:2 (2017) 1559-1569

Authors:

BD Simmons, RJ Smethurst, Christopher Lintott

Abstract:

The deep connection between galaxies and their supermassive black holes is central to modern astrophysics and cosmology. The observed correlation between galaxy and black hole mass is usually attributed to the contribution of major mergers to both. We make use of a sample of galaxies whose disk-dominated morphologies indicate a major-merger-free history and show that such systems are capable of growing supermassive black holes at rates similar to quasars. Comparing black hole masses to conservative upper limits on bulge masses, we show that the black holes in the sample are typically larger than expected if processes creating bulges are also the primary driver of black hole growth. The same relation between black hole and total stellar mass of the galaxy is found for the merger-free sample as for a sample which has experienced substantial mergers, indicating that major mergers do not play a significant role in controlling the coevolution of galaxies and black holes. We suggest that more fundamental processes which contribute to galaxy assembly are also responsible for black hole growth.
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Galaxy Zoo: Finding offset discs and bars in SDSS galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 469:3 (2017) 3363-3373

Authors:

Sandor I Kruk, Christopher J Lintott, Brooke D Simmons, SP Bamford, CN Cardamone, L Fortson, RE Hart, B Häußler, KL Masters, RC Nichol, K Schawinski, Rebecca J Smethurst

Abstract:

We use multi-wavelength SDSS images and Galaxy Zoo morphologies to identify a sample of $\sim$$270$ late-type galaxies with an off-centre bar. We measure offsets in the range 0.2-2.5 kpc between the photometric centres of the stellar disc and stellar bar. The measured offsets correlate with global asymmetries of the galaxies, with those with largest offsets showing higher lopsidedness. These findings are in good agreement with predictions from simulations of dwarf-dwarf tidal interactions producing off-centre bars. We find that the majority of galaxies with off-centre bars are of Magellanic type, with a median mass of $10^{9.6} M_{\odot}$, and 91% of them having $M_{\star}<3\times10^{10} M_{\odot}$, the characteristic mass at which galaxies start having higher central concentrations attributed to the presence of bulges. We conduct a search for companions to test the hypothesis of tidal interactions, but find that a similar fraction of galaxies with offset bars have companions within 100 kpc as galaxies with centred bars. Although this may be due to the incompleteness of the SDSS spectroscopic survey at the faint end, alternative scenarios that give rise to offset bars such as interactions with dark companions or the effect of lopsided halo potentials should be considered. Future observations are needed to confirm possible low mass companion candidates and to determine the shape of the dark matter halo, in order to find the explanation for the off-centre bars in these galaxies.
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Transforming Libraries and Archives through Crowdsourcing

D-Lib Magazine CNRI Acct 23:5/6 (2017)

Authors:

Victoria Van Hyning, Samantha Blickhan, Laura Trouille, Chris Lintott
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Galaxy Zoo: the interplay of quenching mechanisms in the group environment

Monthly Notices of the Royal Astronomical Society Oxford University Press 469:3 (2017) 3670-3687

Authors:

Rebecca J Smethurst, Christopher Lintott, SP Bamford, RE Hart, Sandor J Kruk, KL Masters, RC Nichol, BD Simmons

Abstract:

Does the environment of a galaxy directly influence the quenching history of a galaxy? Here we investigate the detailed morphological structures and star formation histories of a sample of SDSS group galaxies with both classifications from Galaxy Zoo 2 and NUV detections in GALEX. We use the optical and NUV colours to infer the quenching time and rate describing a simple exponentially declining SFH for each galaxy, along with a control sample of field galaxies. We find that the time since quenching and the rate of quenching do not correlate with the relative velocity of a satellite but are correlated with the group potential. This quenching occurs within an average quenching timescale of ∼2.5 Gyr from star forming to complete quiescence, during an average infall time (from ∼10R200 to 0.01R200) of ∼2.6 Gyr. Our results suggest that the environment does play a direct role in galaxy quenching through quenching mechanisms which are correlated with the group potential, such as harassment, interactions or starvation. Environmental quenching mechanisms which are correlated with satellite velocity, such as ram pressure stripping, are not the main cause of quenching in the group environment. We find that no single mechanism dominates over another, except in the most extreme environments or masses. Instead an interplay of mergers, mass & morphological quenching and environment driven quenching mechanisms dependent on the group potential drive galaxy evolution in groups.
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Galaxy Zoo: star-formation versus spiral arm number

Monthly Notices of the Royal Astronomical Society Oxford University Press 468:2 (2017) 1850-1863

Authors:

Ross E Hart, Steven P Bamford, Kevin RV Casteels, Sandor J Kruk, Christopher Lintott, Karen L Masters

Abstract:

Spiral arms are common features in low-redshift disc galaxies, and are prominent sites of star-formation and dust obscuration. However, spiral structure can take many forms: from galaxies displaying two strong `grand design' arms, to those with many `flocculent' arms. We investigate how these different arm types are related to a galaxy's star-formation and gas properties by making use of visual spiral arm number measurements from Galaxy Zoo 2. We combine UV and mid-IR photometry from GALEX and WISE to measure the rates and relative fractions of obscured and unobscured star formation in a sample of low-redshift SDSS spirals. Total star formation rate has little dependence on spiral arm multiplicity, but two-armed spirals convert their gas to stars more efficiently. We find significant differences in the fraction of obscured star-formation: an additional $\sim 10$ per cent of star-formation in two-armed galaxies is identified via mid-IR dust emission, compared to that in many-armed galaxies. The latter are also significantly offset below the IRX-$\beta$ relation for low-redshift star-forming galaxies. We present several explanations for these differences versus arm number: variations in the spatial distribution, sizes or clearing timescales of star-forming regions (i.e., molecular clouds), or contrasting recent star-formation histories.
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