50 research outputs found
Missing Giants: Predictions on Dust-Obscured Galaxy Stellar Mass Assembly Throughout Cosmic Time
Due to their extremely dust-obscured nature, much uncertainty still exists
surrounding the stellar mass growth and content in dusty, star-forming galaxies
(DSFGs) at . In this work, we present a numerical model built using
empirical data on DSFGs to estimate their stellar mass contributions across the
first 10 Gyr of cosmic time. We generate a dust-obscured stellar mass
function that extends beyond the mass limit of star-forming stellar mass
functions in the literature, and predict that massive DSFGs constitute as much
as of all star-forming galaxies with M M at
. We predict the number density of massive DSFGs and find general
agreement with observations, although more data is needed to narrow wide
observational uncertainties. We forward model mock massive DSFGs to their
quiescent descendants and find remarkable agreement with observations from the
literature demonstrating that, to first order, massive DSFGs are a sufficient
ancestral population to describe the prevalence of massive quiescent galaxies
at . We predict that massive DSFGs and their descendants contribute as
much as to the cosmic stellar mass density during the peak of cosmic
star formation, and predict an intense epoch of population growth during the
Gyr from to 3 during which the majority of the most massive
galaxies at high- grow and then quench. Future studies seeking to understand
massive galaxy growth and evolution in the early Universe should strategize
synergies with data from the latest observatories (e.g. JWST and ALMA) to
better include the heavily dust-obscured galaxy population.Comment: 22 pages, 9 figures, submitted to Ap
Clinical Skills Development in the Virtual Learning Environment: Adapting to a New World
The rapid transition to distance learning in response to the unexpected SARS-CoV-2/COVID-19 pandemic led to disruption of clinical skills development, which are typically conducted face-to-face. Consequently, faculty adapted their courses, using a multitude of active learning modalities, to meet student learning objectives in the didactic and experiential settings. Strategies and considerations to implement innovative delivery methods and address potential challenges are elucidated. Furthermore, integration of a layered learning approach may allow for more broad perspectives and allow additional interactions and feedback, which is especially necessary in the virtual environment.https://digitalcommons.chapman.edu/pharmacy_books/1025/thumbnail.jp
JWST and ALMA discern the assembly of structural and obscured components in a high-redshift starburst galaxy
We present observations and analysis of the starburst, PACS-819, at z=1.45
( M), using high-resolution (;
0.8 kpc) ALMA and multi-wavelength JWST images from the COSMOS-Web program.
Dissimilar to HST/ACS images in the rest-frame UV, the redder NIRCam and MIRI
images reveal a smooth central mass concentration and spiral-like features,
atypical for such an intense starburst. Through dynamical modeling of the CO
J=5--4 emission with ALMA, PACS-819 is rotation-dominated thus has a disk-like
nature. However, kinematic anomalies in CO and asymmetric features in the bluer
JWST bands (e.g., F150W) support a more disturbed nature likely due to
interactions. The JWST imaging further enables us to map the distribution of
stellar mass and dust attenuation, thus clarifying the relationships between
different structural components, not discernable in the previous HST images.
The CO J = 5 -- 4 and FIR dust continuum emission are co-spatial with a
heavily-obscured starbursting core (<1 kpc) which is partially surrounded by
much less obscured star-forming structures including a prominent arc, possibly
a tidally-distorted dwarf galaxy, and a clump, either a sign of an ongoing
violent disk instability or a recently accreted low-mass satellite. With
spatially-resolved maps, we find a high molecular gas fraction in the central
area reaching (/) and short depletion times
( 120 Myrs) across the entire system. These
observations provide insights into the complex nature of starbursts in the
distant universe and underscore the wealth of complementary information from
high-resolution observations with both ALMA and JWST.Comment: 18 pages, 12 figures, Submitted to Ap
Efficient NIRCam Selection of Quiescent Galaxies at 3 < z < 6 in CEERS
© 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Substantial populations of massive quiescent galaxies at z ≥ 3 challenge our understanding of rapid galaxy growth and quenching over short timescales. In order to piece together this evolutionary puzzle, more statistical samples of these objects are required. Established techniques for identifying massive quiescent galaxies are increasingly inefficient and unconstrained at z > 3. As a result, studies report that as much as 70% of quiescent galaxies at z > 3 may be missed from existing surveys. In this work, we propose a new empirical color selection technique designed to select massive quiescent galaxies at 3 ≲ z ≲ 6 using JWST NIRCam imaging data. We use empirically constrained galaxy spectral energy distribution (SED) templates to define a region in the F277W − F444W versus F150W − F277W color plane that captures quiescent galaxies at z > 3. We apply these color selection criteria to the Cosmic Evolution Early Release Science (CEERS) Survey and use SED fitting on sources in the region to identify 44 candidate z ≳ 3 quiescent galaxies. Over half of these sources are newly discovered and, on average, exhibit specific star formation rates of poststarburst galaxies. Most of these sources would not be discovered using canonical UVJ diagrams. We derive volume density estimates of n ∼ 1–4 × 10−5 Mpc−3 at 3 < z < 5, finding excellent agreement with existing reports on similar populations in the CEERS field. Thanks to NIRCam’s wavelength coverage and sensitivity, this technique provides an efficient tool to search for large samples of these rare galaxies.Peer reviewe
Uncovering a Massive z~7.65 Galaxy Hosting a Heavily Obscured Radio-Loud QSO Candidate in COSMOS-Web
In this letter, we report the discovery of the highest redshift, heavily
obscured, radio-loud QSO candidate selected using JWST NIRCam/MIRI, mid-IR,
sub-mm, and radio imaging in the COSMOS-Web field. Using multi-frequency radio
observations and mid-IR photometry, we identify a powerful, radio-loud (RL),
growing supermassive black hole (SMBH) with significant spectral steepening of
the radio SED ( mJy, ,
, ). In conjunction
with ALMA, deep ground-based observations, ancillary space-based data, and the
unprecedented resolution and sensitivity of JWST, we find no evidence of QSO
contribution to the UV/optical/NIR data and thus infer heavy amounts of
obscuration (N cm). Using the wealth of deep UV
to sub-mm photometric data, we report a singular solution photo-z of
= 7.65 and estimate an extremely massive
host-galaxy (). This
source represents the furthest known obscured RL QSO candidate, and its level
of obscuration aligns with the most representative but observationally scarce
population of QSOs at these epochs.Comment: Submitted to ApJL, Comments welcom
Comparison between dynamic [18F]Fluoroethyltyrosine PET/CT and advanced MRI in cerebral high and low grade gliomas.\ua0 ;\ua0
Comparison between dynamic [18F]Fluoroethyltyrosine PET/CT and advanced MRI in cerebral high and low grade gliomas L. Picori, U. Rozzanigo, D. Donner, M. Erini, P. Feraco, M. Recla, F. Chierichetti; Santa Chiara Hospital, Trento, ITALY. Aim/Introduction: To investigate if dynamic [18F]fluoroethyl- L-tyrosine [18F]FET PET/CT improves the diagnosis in patients with suspected new or recurrent cerebral gliomas, respect to advanced MRI techniques. Materials and Methods: We retrospectively evaluated 20 patients who performed [18F] FET by a PET/CT tomograph: 15 had an indeterminate brain lesion, 5 a suspect glioma recurrence. All patients underwent a 40 minutes dynamic [18F]FET PET/CT acquisition and two different sequences, between 5-15 minutes and 20-30 minutes. For dynamic studies time-activity and time to peak curves were extracted using different region-of-interest (ROIs) and volume of interest (VOIs) definitions. MRI was performed with a 1.5T scanner just before [18F]FET-PET/CT using perfusion (PWI) and diffusion (DWI) weighted imaging: afterwards rCBV and ADC values were calculated placing the VOIs on the solid components of the lesion. In case of doubt (13 cases) single-voxel MR spectroscopy was performed. Multimodality imaging by fusion of PET/CT and different MRI sequences was performed for a joint assessment (radiologist and nuclear physician). Results: Final diagnosis was based on histology in 8 patients who underwent neurosurgery (5 HGG, 3 LGG) and on follow-up imaging in 12 patients (8 tumor progression, 4 stable benign lesion). On the basis of [18F]FET- PET, 7 cases were classified as high uptake (2 glioma recurrence and 5 new diagnosis of HGG tumor), 8 as low uptake (4 glioma recurrence, 2 new diagnosis of LGG tumor, 1 tumor progression, 1 tumefactive demielinating lesion) and 5 as no uptake (1 new diagnosis of LGG tumor, 4 stable benign lesion). Sensibility for dynamic [18F]FET-PET was 93% and specificity was 80%. Multiparametric MRI was in agreement with [18F]FET-PET in all 7 cases of high uptake and in 5 cases of low uptake. [18F]FET- PET helped to classify 6 MRI indeterminate lesions (2 suspect radionecrosis with pathologic uptake, 4 benign lesions without uptake). In 2 cases there was a discrepancy between MRI and PET: 1 tumefactive demielinating lesion was classified by [18F] FET as low uptake lesion, 1 LGG confirmed at histology showed no uptake. Conclusion: In our experience, adding quantitative data, such as dynamic acquisition in PET/CT by aminoacid tracer like [18F]FET, to rCBV and ADC maps in advanced MRI is crucial for a better comprehension of tumor lesions and to assess grading. Dynamic [18F]FET-PET/CT and multiparametric MR imaging have a very high sensibility to detect new tumoral lesions or suspect glioma recurrence. Agreement between PET and MRI is essential to improve diagnostic specificity. References: None