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The Compton-thick AGN population and the N H distribution of low-mass AGN in our cosmic backyard (2025)
Journal Article
Annuar, A., Alexander, D. M., Gandhi, P., Lansbury, G. B., Rosli, M. N., Stern, D., Asmus, D., Ballantyne, D. R., Baloković, M., Bauer, F. E., Boorman, P. G., Brandt, W. N., Brightman, M., Chen, C. T. J., Del Moro, A., Farrah, D., Harrison, F. A., Koss, M. J., Lanz, L., Marchesi, S., …Zappacosta, L. (2025). The Compton-thick AGN population and the N H distribution of low-mass AGN in our cosmic backyard. Monthly Notices of the Royal Astronomical Society, 540(4), 3827-3849. https://doi.org/10.1093/mnras/staf956

We present a census of the Compton-thick (CT) active galactic nucleus (AGN) population and the column density () distribution of AGN in our cosmic backyard using a mid-infrared selected AGN sample within 15 Mpc. The column densities are measured from... Read More about The Compton-thick AGN population and the N H distribution of low-mass AGN in our cosmic backyard.

Sub-second optical/near-infrared quasi-periodic oscillations from the black hole X-ray transient Swift J1727.8–1613 (2025)
Journal Article
Vincentelli, F. M., Shahbaz, T., Casella, P., Dhillon, V. S., Paice, J., Altamirano, D., Segura, N. C., Fender, R., Gandhi, P., Littlefair, S., Maccarone, T., Malzac, J., O’Brien, K., Russell, D. M., Tetarenko, A. J., Uttley, P., & Veledina, A. (2025). Sub-second optical/near-infrared quasi-periodic oscillations from the black hole X-ray transient Swift J1727.8–1613. Monthly Notices of the Royal Astronomical Society, 539(3), 2347-2361. https://doi.org/10.1093/mnras/staf600

We report on the detection of optical/near-infrared (O-IR) quasi-periodic oscillations (QPOs) from the black hole (BH) X-ray transient Swift J1727.8–1613. We obtained three X-ray and O-IR high-time-resolution observations of the source during its int... Read More about Sub-second optical/near-infrared quasi-periodic oscillations from the black hole X-ray transient Swift J1727.8–1613.

The Galaxy Activity, Torus, and Outflow Survey (GATOS). IV. Exploring Ionized Gas Outflows in Central Kiloparsec Regions of GATOS Seyferts (2024)
Journal Article
Zhang, L., Packham, C., Hicks, E. K. S., Davies, R. I., Shimizu, T. T., Alonso-Herrero, A., Hermosa Muñoz, L., García-Bernete, I., Pereira-Santaella, M., Audibert, A., López-Rodríguez, E., Bellocchi, E., Bunker, A. J., Combes, F., Díaz-Santos, T., Gandhi, P., García-Burillo, S., García-Lorenzo, B., González-Martín, O., Imanishi, M., …Rouan, D. (2024). The Galaxy Activity, Torus, and Outflow Survey (GATOS). IV. Exploring Ionized Gas Outflows in Central Kiloparsec Regions of GATOS Seyferts. Astrophysical Journal, 974(2), 195. https://doi.org/10.3847/1538-4357/ad6a4b

Utilizing JWST MIRI/Medium Resolution Spectrograph integral field unit observations of the kiloparsec-scale central regions, we showcase the diversity of ionized gas distributions and kinematics in six nearby Seyfert galaxies included in the GATOS su... Read More about The Galaxy Activity, Torus, and Outflow Survey (GATOS). IV. Exploring Ionized Gas Outflows in Central Kiloparsec Regions of GATOS Seyferts.

GATOS: missing molecular gas in the outflow of NGC 5728 revealed by JWST (2024)
Journal Article
Davies, R., Shimizu, T., Pereira-Santaella, M., Alonso-Herrero, A., Audibert, A., Bellocchi, E., Boorman, P., Campbell, S., Cao, Y., Combes, F., Delaney, D., Díaz-Santos, T., Eisenhauer, F., Esparza Arredondo, D., Feuchtgruber, H., Förster Schreiber, N. M., Fuller, L., Gandhi, P., García-Bernete, I., García-Burillo, S., …Zhang, L. (2024). GATOS: missing molecular gas in the outflow of NGC 5728 revealed by JWST. Astronomy & Astrophysics, 689, Article A263. https://doi.org/10.1051/0004-6361/202449875

The ionisation cones of NGC 5728 have a deficit of molecular gas based on millimetre observations of CO (2-1) emission. Although photoionisation from the active nucleus may lead to suppression of this transition, warm molecular gas can still be prese... Read More about GATOS: missing molecular gas in the outflow of NGC 5728 revealed by JWST.

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.

CorrSim: a multiwavelength timing observation simulator (2024)
Journal Article
Paice, J. A., Misra, R., & Gandhi, P. (2024). CorrSim: a multiwavelength timing observation simulator. RAS Techniques and Instruments, 3(1), 453-471. https://doi.org/10.1093/rasti/rzae032

Studying the rapid variability of many astronomical objects is key to understanding the underlying processes at play. However, obtaining data well-suited to this task can be tricky, especially for simultaneous multiwavelength observations. Parameters... Read More about CorrSim: a multiwavelength timing observation simulator.

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.

The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd (2023)
Journal Article
Wang, Y., Baldi, R. D., del Palacio, S., Guolo, M., Yang, X., Zhang, Y., …Dai, L. (2023). The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd. Monthly Notices of the Royal Astronomical Society, 520(2), 2417–2435. https://doi.org/10.1093/mnras/stad101

AT 2019avd is a nuclear transient detected from infrared to soft X-rays, though its nature is yet unclear. The source has shown two consecutive flaring episodes in the optical and the infrared bands, and its second flare was covered by X-ray monitori... Read More about The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd.

The Phoenix galaxy as seen by NuSTAR (2017)
Journal Article
Masini, A., Comastri, A., Puccetti, S., Baloković, M., Gandhi, P., Guainazzi, M., …Zhang, W. (2017). The Phoenix galaxy as seen by NuSTAR. Astronomy & Astrophysics, 597, Article A100. https://doi.org/10.1051/0004-6361/201629444

Aims. We study the long-term variability of the well-known Seyfert 2 galaxy Mrk 1210 (also known as UGC 4203, or the Phoenix galaxy). Methods. The source was observed by many X-ray facilities in the last 20 yr. Here we present a NuSTAR observation an... Read More about The Phoenix galaxy as seen by NuSTAR.

SN 2009js at the Crossroads between Normal and Subluminous Type IIP Supernovae: Optical and Mid-infrared Evolution (2013)
Journal Article
Gandhi, P., Yamanaka, M., Tanaka, M., Nozawa, T., Kawabata, K., Saviane, I., …Itoh, R. (2013). SN 2009js at the Crossroads between Normal and Subluminous Type IIP Supernovae: Optical and Mid-infrared Evolution. Astrophysical Journal, 767(2), Article 166. https://doi.org/10.1088/0004-637x/767/2/166

We present a study of SN 2009js in NGC 918. Multi-band Kanata optical photometry covering the first ~120 days shows the source to be a Type IIP SN. Reddening is dominated by that due to our Galaxy. One-year-post-explosion photometry with the New Tech... Read More about SN 2009js at the Crossroads between Normal and Subluminous Type IIP Supernovae: Optical and Mid-infrared Evolution.