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All Outputs (6)

An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals (2025)
Journal Article
Andonie, C., Alexander, D. M., Greenwell, C., Fotopoulou, S., Hickox, R., Rosario, D. J., Villforth, C., Buchner, J., Krogager, J.-K., Laloux, B., Merloni, A., Salvato, M., Streicher, O., & Yan, W. (2025). An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals. Monthly Notices of the Royal Astronomical Society, 539(3), 2202-2229. https://doi.org/10.1093/mnras/staf624

We present the 4MOST (4-metre Multi-Object Spectroscopic Telescope) infrared (IR) AGN survey, the first large-scale optical spectroscopic survey characterizing mid-infrared (MIR) selected obscured active galactic nuclei (AGNs). The survey targets ≈ 2... Read More about An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals.

The NuSTAR Local AGN N H Distribution Survey (NuLANDS). I. Toward a Truly Representative Column Density Distribution in the Local Universe (2024)
Journal Article
Boorman, P. G., Gandhi, P., Buchner, J., Stern, D., Ricci, C., Baloković, M., Asmus, D., Harrison, F. A., Svoboda, J., Greenwell, C., Koss, M. J., Alexander, D. M., Annuar, A., Bauer, F. E., Brandt, W. N., Brightman, M., Civano, F., Chen, C. T. J., Farrah, D., Forster, K., …Zappacosta, L. (2024). The NuSTAR Local AGN N H Distribution Survey (NuLANDS). I. Toward a Truly Representative Column Density Distribution in the Local Universe. Astrophysical Journal, 978(1), Article 118. https://doi.org/10.3847/1538-4357/ad8236

Hard X-ray-selected samples of active galactic nuclei (AGN) provide one of the cleanest views of supermassive black hole accretion but are biased against objects obscured by Compton-thick gas column densities of N <inf>H</inf> > 10<sup>24</sup> cm<su... Read More about The NuSTAR Local AGN N H Distribution Survey (NuLANDS). I. Toward a Truly Representative Column Density Distribution in the Local Universe.

Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe (2024)
Journal Article
Akylas, A., Georgantopoulos, I., Gandhi, P., Boorman, P., & Greenwell, C. L. (2024). Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe. Astronomy & Astrophysics, 692, Article A250. https://doi.org/10.1051/0004-6361/202451906

X-ray surveys provide the most efficient means for the detection of active galactic nuclei (AGNs). However, they do face difficulties in detecting the most heavily obscured Compton-thick AGNs. The BAT detector on board the Gehrels/Swift mission, oper... Read More about Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe.

The NuSTAR Serendipitous Survey: The 80 Month Catalog and Source Properties of the High-energy Emitting Active Galactic Nucleus and Quasar Population (2024)
Journal Article
Klindt, L., Lansbury, G. B., Rosario, D. J., Alexander, D. M., Aird, J., Stern, D., Forster, K., Koss, M. J., Greenwell, C. L., Bauer, F. E., Ricci, C., Tomsick, J., Brandt, W. N., Connor, T., Boorman, P. G., Annuar, A., Ballantyne, D. R., Chen, C.-T., Civano, F., Comastri, A., …van Soelen, B. (2024). The NuSTAR Serendipitous Survey: The 80 Month Catalog and Source Properties of the High-energy Emitting Active Galactic Nucleus and Quasar Population. Astrophysical Journal Supplement, 273(2), Article 20. https://doi.org/10.3847/1538-4365/ad4a71

We present a catalog of hard X-ray serendipitous sources detected in the first 80 months of observations by the Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR serendipitous survey 80 month (NSS80) catalog has an unprecedented ∼62 Ms of ef... Read More about The NuSTAR Serendipitous Survey: The 80 Month Catalog and Source Properties of the High-energy Emitting Active Galactic Nucleus and Quasar Population.

A population of Optically Quiescent Quasars from WISE and SDSS (2023)
Journal Article
Greenwell, C., Gandhi, P., Stern, D., Lansbury, G., Mainieri, V., Boorman, P., & Toba, Y. (2024). A population of Optically Quiescent Quasars from WISE and SDSS. Monthly Notices of the Royal Astronomical Society, 527(4), 12065-12090. https://doi.org/10.1093/mnras/stad3964

The growth of active galactic nuclei (AGNs) occurs under some form of obscuration in a large fraction of the population. The difficulty in constraining this population leads to high uncertainties in cosmic X-ray background and galaxy evolution models... Read More about A population of Optically Quiescent Quasars from WISE and SDSS.