Browsing by Author "Simmons, Brooke D."

Now showing 1 - 9 of 9
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    Chandra Observations of Galaxy Zoo Mergers : Frequency of Binary Active Nuclei in Massive Mergers.
    (2012) Teng, Stacy H.; Treister, Ezequiel; Schawinski, Kevin; Urry, C. Meg; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.; Simmons, Brooke D.
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    Do Moderate-Luminosity Active Galactic Nuclei Suppress Star Formation?
    (2009) Schawinski, Kevin; Treister, Ezequiel; Virani, Shanil; Simmons, Brooke D.; Urry, C. Megan; Kaviraj, Sugata; Kushkuley, Bronika
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    Evidence for Three Accreting Black Holes in a Galaxy at z ~ 1.35: A Snapshot of Recently Formed Black Hole Seeds?
    (2011) Schawinski, Kevin; Treister, Ezequiel; Urry, C. Meg; Simmons, Brooke D.; Natarajan, Priyamvada; Glikman, Eilat
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    Extending the evolution of the stellar mass-size relation at z ≤ 2 to low stellar mass galaxies from HFF and CANDELS
    (2021) Nedkova, Kalina, V; Haussler, Boris; Marchesini, Danilo; Dimauro, Paola; Brammer, Gabriel; Eigenthaler, Paul; Feinstein, Adina D.; Ferguson, Henry C.; Huertas-Company, Marc; Johnston, Evelyn J.; Kado-Fong, Erin; Kartaltepe, Jeyhan S.; Labbe, Ivo; Lange-Vagle, Daniel; Martis, Nicholas S.; McGrath, Elizabeth J.; Muzzin, Adam; Oesch, Pascal; Ordenes-Briceno, Yasna; Puzia, Thomas; Shipley, Heath, V; Simmons, Brooke D.; Skelton, Rosalind E.; Stefanon, Mauro; van der Wel, Arjen; Whitaker, Katherine E.
    We reliably extend the stellar mass-size relation over 0.2 <= z <= 2 to low stellar mass galaxies by combining the depth of Hubble Frontier Fields with the large volume covered by CANDELS. Galaxies are simultaneously modelled in multiple bands using the tools developed by the MegaMorph project, allowing robust size (i.e. half-light radius) estimates even for small, faint, and high redshift galaxies. We show that above 10(7) M-circle dot, star-forming galaxies are well represented by a single power law on the mass-size plane over our entire redshift range. Conversely, the stellar mass-size relation is steep for quiescent galaxies with stellar masses >= 10(10.3)M(circle dot) and flattens at lower masses, regardless of whether quiescence is selected based on star-formation activity, rest-frame colours, or structural characteristics. This flattening occurs at sizes of similar to 1 kpc at z <= 1. As a result, a double power law is preferred for the stellar mass-size relation of quiescent galaxies, at least above 10(7)M(circle dot). We find no strong redshift dependence in the slope of the relation of star-forming galaxies as well as of high mass quiescent galaxies. We also show that star-forming galaxies with stellar masses >= 10(9.5)M(circle dot) and quiescent galaxies with stellar masses >= 10(10.3)M(circle dot) have undergone significant size growth since z similar to 2, as expected; however, low mass galaxies have not. Finally, we supplement our data with predominantly quiescent dwarf galaxies from the core of the Fornax cluster, showing that the stellar mass-size relation is continuous below 10(7)M(circle dot), but a more complicated functional form is necessary to describe the relation.
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    Heavily obscured quasar host galaxies at z ∼ 2 are discs, not major mergers.
    (2012) Schawinski, Kevin; Treister, Ezequiel; Simmons, Brooke D.; Urry, C. Meg; Glikman, Eilat
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    Major Galaxy Mergers Only Trigger the Most Luminous Active Galactic Nuclei.
    (2012) Treister, Ezequiel; Schawinski, Kevin; Urry, C. Meg; Simmons, Brooke D.
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    Obscured GOODS Active Galactic Nuclei and Their Host Galaxies at z < 1.25 : The Slow Black Hole Growth Phase.
    (2011) Simmons, Brooke D.; Treister, Ezequiel; Van Duyne, J.; Urry, C. Meg; Koekemoer, A. M.; Grogin, N. A.
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    Signatures of feedback in the spectacular extended emission region of NGC 5972
    (2023) Harvey, Thomas; Maksym, W. Peter; Keel, William; Koss, Michael; Bennert, Vardha N.; Chojnowski, S. Drew; Treister, Ezequiel; Finlez, Carolina; Lintott, Chris J.; Moiseev, Alexei; Simmons, Brooke D.; Sartori, Lia F.; Urry, Megan
    We present Chandra X-ray Observatory observations and Space Telescope Imaging Spectrograph spectra of NGC 5972, one of the 19 ‘Voorwerpjes’ galaxies. This galaxy contains an extended emission-line region (EELR) and an arcsecond scale nuclear bubble. NGC 5972 is a faded active galactic nucleus (AGN), with EELR luminosity suggesting a 2.1 dex decrease in Lbol in the last ∼5 × 104 yr. We investigate the role of AGN feedback in exciting the EELR and bubble given the long-term variability and potential accretion state changes. We detect broad-band (0.3–8 keV) X-ray emission in the near-nuclear regions, coincident with the [O III] bubble, as well as diffuse soft X-ray emission coincident with the EELR. The soft nuclear (0.5–1.5 keV) emission is spatially extended and the spectra are consistent with two APEC thermal populations (∼0.80 and ∼0.10 keV). We find a bubble age >2.2 Myr, suggesting formation before the current variability. We find evidence for efficient feedback with Pkin/Lbol ∼ 0.8 per cent, which may be overestimated given the recent Lbol variation. [O III] kinematics show a 300 km s−1 high-ionization velocity consistent with disturbed rotation or potentially the line-of-sight component of a ∼780 km s−1 thermal X-ray outflow capable of driving strong shocks to photoionize the precursor material. We explore possibilities to explain the overall jet, radio lobe and EELR misalignment including evidence for a double supermassive black hole which could support a complex misaligned system.
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    The green valley is a red herring : Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early- and late-type galaxies.
    (2014) Schawinski, Kevin; Treister, Ezequiel; Urry, C. Megan; Simmons, Brooke D.; Fortson, Lucy; Kaviraj, Sugata; Keel, William C.; Lintott, Chris J.; Masters, K. L.; Nichol, Robert C.; Sarzi, Marc