/library/oar/handle/123456789/16096 2025-12-29T18:45:13Z /library/oar/handle/123456789/141900 Title: Hidden little monsters : spectroscopic identification of low-mass, broad-line AGNs at z > 5 with CEERS Authors: Kocevski, Dale D.; Onoue, Masafusa; Inayoshi, Kohei; Trump, Jonathan R.; Haro, Pablo Arrabal; Grazian, Andrea; Dickinson, Mark; Finkelstein, Steven L.; Kartaltepe, Jeyhan S.; Hirschmann, Michaela; Aird, James; Holwerda, Benne W.; Fujimoto, Seiji; Juneau, Stéphanie; Amorín, Ricardo O.; Backhaus, Bren E.; Bagley, Micaela B.; Barro, Guillermo; Bell, Eric F.; Bisigello, Laura; Calabrò, Antonello; Cleri, Nikko J.; Cooper, M. C.; Ding, Xuheng; Grogin, Norman A.; Ho, Luis C.; Hutchison, Taylor A.; Inoue, Akio K.; Jiang, Linhua; Jones, Brenda; Koekemoer, Anton M.; Li, Wenxiu; Li, Zhengrong; McGrath, Elizabeth J.; Molina, Juan; Papovich, Casey; Pérez-González, Pablo G.; Pirzkal, Nor; Wilkins, Stephen M.; Yang, Guang; Yung, L. Y. Aaron Abstract: We report on the discovery of two low-luminosity, broad-line active galactic nuclei (AGNs) at z > 5 identified using JWST NIRSpec spectroscopy from the Cosmic Evolution Early Release Science (CEERS) survey. We detect broad Hα emission in the spectra of both sources, with FWHM of 2060 ± 290 km s−1 and 1800 ± 200 km s−1, resulting in virial black hole (BH) masses that are 1–2 dex below those of existing samples of luminous quasars at z > 5. The first source, CEERS 2782 at z = 5.242, is 2–3 dex fainter than known quasars at similar redshifts and was previously identified as a candidate low-luminosity AGN based on its morphology and rest-frame optical spectral energy distribution (SED). We measure a BH mass of MBH = (1.3 ± 0.4) × 107M⊙, confirming that this AGN is powered by the least massive BH known in the Universe at the end of cosmic reionization. The second source, CEERS 746 at z = 5.624, is inferred to be a heavily obscured, broad-line AGN caught in a transition phase between a dust-obscured starburst and an unobscured quasar. We estimate its BH mass to be in the range of MBH ≃ (0.9–4.7) × 107M⊙, depending on the level of dust obscuration assumed. We perform SED fitting to derive host stellar masses, M⋆, allowing us to place constraints on the BH–galaxy mass relationship in the lowest mass range yet probed in the early Universe. The MBH/M⋆ ratio for CEERS 2782, in particular, is consistent with or higher than the empirical relationship seen in massive galaxies at z = 0. We examine the narrow emission line ratios of both sources and find that their location on the BPT and OHNO diagrams is consistent with model predictions for moderately low metallicity AGNs with Z/Z⊙ ≃ 0.2–0.4. The spectroscopic identification of low-luminosity, broad-line AGNs at z > 5 with MBH ≃ 107M⊙ demonstrates the capability of JWST to push BH masses closer to the range predicted for the BH seed population and provides a unique opportunity to study the early stages of BH–galaxy assembly. 2023-01-01T00:00:00Z /library/oar/handle/123456789/141897 Title: CEERS epoch 1 NIRCam imaging : reduction methods and simulations enabling early JWST science results Authors: Bagley, Micaela B.; Finkelstein, Steven L.; Koekemoer, Anton M.; Ferguson, Henry C.; Haro, Pablo Arrabal; Dickinson, Mark; Kartaltepe, Jeyhan S.; Papovich, Casey; Pérez-González, Pablo G.; Pirzkal, Nor; Somerville, Rachel S.; Willmer, Christopher N. A.; Yang, Guang; Yung, L. Y. Aaron; Fontana, Adriano; Grazian, Andrea; Grogin, Norman A.; Hirschmann, Michaela; Kewley, Lisa J.; Kirkpatrick, Allison; Kocevski, Dale D.; Lotz, Jennifer M.; Medrano, Aubrey; Morales, Alexa M.; Pentericci, Laura; Ravindranath, Swara; Trump, Jonathan R.; Wilkins, Stephen M.; Calabrò, Antonello; Cooper, M. C.; Costantin, Luca; de la Vega, Alexander; Hilbert, Bryan; Hutchison, Taylor A.; Larson, Rebecca L.; Lucas, Ray A.; McGrath, Elizabeth J.; Ryan, Russell; Wang, Xin; Wuyts, Stijn Abstract: We present the data release and data reduction process for the Epoch 1 NIRCam observations for the Cosmic Evolution Early Release Science Survey (CEERS). These data consist of NIRCam imaging in six broadband filters (F115W, F150W, F200W, F277W, F356W and F444W) and one medium-band filter (F410M) over four pointings, obtained in parallel with primary CEERS MIRI observations. We reduced the NIRCam imaging with the JWST Calibration Pipeline, with custom modifications and reduction steps designed to address additional features and challenges with the data. Here we provide a detailed description of each step in our reduction and a discussion of future expected improvements. Our reduction process includes corrections for known prelaunch issues such as 1/f noise, as well as in-flight issues including snowballs, wisps, and astrometric alignment. Many of our custom reduction processes were first developed with prelaunch simulated NIRCam imaging over the full 10 CEERS NIRCam pointings. We present a description of the creation and reduction of this simulated data set in the Appendix. We provide mosaics of the real images in a public release, as well as our reduction scripts with detailed explanations to allow users to reproduce our final data products. These represent one of the first official public data sets released from the Directors Discretionary Early Release Science (DD-ERS) program. 2023-01-01T00:00:00Z /library/oar/handle/123456789/141887 Title: A CEERS discovery of an accreting supermassive black hole 570Myr after the Big Bang : identifying a progenitor of massive z>6 quasars Authors: Larson, Rebecca L.; Finkelstein, Steven L.; Kocevski, Dale D.; Hutchison, Taylor A.; Trump, Jonathan R.; Haro, Pablo Arrabal; Bromm, Volker; Cleri, Nikkol J.; Dickinson, Mark; Fujimoto, Seiji; Kartaltepe, Jeyhan S.; Koekemoer, Anton M.; Papovich, Casey; Pirzkal, Nor; Tacchella, Sandro; Zavala, Jorge A.; Bagley, Micaela; Behroozi, Peter; Champagne, Jaclyn B.; Cole, Justin W.; Jung, Intae; Morales, Alexa M.; Yang, Guang; Zhang, Haowen; Zitrin, Adi; Amorín, Ricardo O.; Burgarella, Denis; Casey, Caitlin M.; Ortiz, Óscar A. Chávez; Cox, Isabella G.; Chworowsky6, Katherine; Fontana, Adriano; Gawiser, Eric; Grazian, Andrea; Grogin, Norman A.; Harish, Santosh; Hathi, Nimish P.; Hirschmann, Michaela; Holwerda, Benne W.; Juneau, Stéphanie; Leung, Gene C. K.; Lucas, Ray A.; McGrath, Elizabeth J.; Pérez-González, Pablo G.; Rigby, Jane R.; Seillé, Lise-Marie; Simons, Raymond C.; de la Vega, Alexander; Weiner, Benjamin J.; Wilkins, Stephen M.; Yung, L. Y. Aaron Abstract: We report the discovery of an accreting supermassive black hole at z = 8.679. This galaxy, denoted here as CEERS_1019, was previously discovered as a Lyα-break galaxy by Hubble with a Lyα redshift from Keck. As part of the Cosmic Evolution Early Release Science (CEERS) survey, we have observed this source with JWST/NIRSpec, MIRI, NIRCam, and NIRCam/WFSS and uncovered a plethora of emission lines. The Hβ line is best fit by a narrow plus a broad component, where the latter is measured at 2.5σ with an FWHM ∼1200 km s−1. We conclude this originates in the broadline region of an active galactic nucleus (AGN). This is supported by the presence of weak high-ionization lines (N V, N IV], and C III]), as well as a spatial point-source component. The implied mass of the black hole (BH) is log (MBH/M⊙) = 6.95 ± 0.37, and we estimate that it is accreting at 1.2 ± 0.5 times the Eddington limit. The 1–8 μm photometric spectral energy distribution shows a continuum dominated by starlight and constrains the host galaxy to be massive (log M/M⊙ ∼9.5) and highly star-forming (star formation rate, or SFR ∼ 30 M⊙ yr−1; log sSFR ∼ − 7.9 yr−1). The line ratios show that the gas is metal-poor (Z/Z⊙ ∼ 0.1), dense (ne ∼ 103 cm−3), and highly ionized (log U ∼ − 2.1). We use this present highest-redshift AGN discovery to place constraints on BH seeding models and find that a combination of either super-Eddington accretion from stellar seeds or Eddington accretion from very massive BH seeds is required to form this object. 2023-01-01T00:00:00Z /library/oar/handle/123456789/141880 Title: Enhancing the northern cross radio telescope for fast radio burst searching Abstract: Fast Radio Bursts (FRBs) are short, bright radio transients whose real-time detection is critical for understanding their origins. This project evaluates and optimises the Heimdall-based detection pipeline of the Northern Cross Radio Telescope for real-time deployment. Using data generated to represent data gathered from the Northern Cross, a structured grid search was performed over key hyperparameters. Performance was quantified using detection accuracy for features including the Signal to Noise Ratio (SNR), Dispersion Measure (DM), and Time of Arrival (ToA), alongside end-to-end runtime. The optimal parameter set achieved high recovery accuracy across all metrics while maintaining processing speeds compatible with real-time operations. These results demonstrate a measurable improvement in the Northern Cross pipeline’s sensitivity–performance balance and strengthen its capability for ongoing FRB searches. Description: M.Sc.(Melit.) 2025-01-01T00:00:00Z