UMBC Physics Department

Permanent URI for this collectionhttp://hdl.handle.net/11603/57

The mission of the Department of Physics at UMBC is based on three pillars: education, research and service to society. We strive to provide outstanding educational opportunities, through instruction and research, for undergraduate physics majors seeking preparation for graduate school or entry into the workforce. We also aim to train graduate students to be leaders in their field of research. Our research goal is to grow and sustain internationally recognized research groups in atmospheric physics, astrophysics, condensed matter physics and quantum optics and information science. Through our teaching of physics to non-science and non-physics majors and through our Physics for Secondary Education Teachers program, we provide professional service to the university community and the State.

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Topological X-states in a quantum impurity model
(2025-01-26) Cavalcante, M. F.; Bonança, Marcus V. S.; Miranda, Eduardo; Deffner, Sebastian
Topological qubits are inherently resistant to noise and errors. However, experimental demonstrations have been elusive as their realization and control is highly complex. In the present work, we demonstrate the emergence of topological X-states in the long-time response of a locally perturbed quantum impurity model. The emergence of the double-qubit state is heralded by the lack of decay of the response function as well as the out-of-time order correlator signifying the trapping of excitations, and hence information in local edge modes.
Signal Processing of Images for Convective Boundary Layer Height Estimation from Radar (SPICER) and multi-instrument verification
(IEEE, 2025-01-13) Porta, Delia Tatiana Della; Demoz, Belay
The study of the planetary boundary layer (PBL) is one of the main topics of the atmospheric community. The current study presents a new algorithm for PBL height determination using a publicly available but unexplored data source, the Weather Service Radar (WSR-88D). The diurnal evolution of the PBL is also known as Convective Boundary Layer (CBL), key in the study of convection and precipitation. This paper presents the Signal Processing of Images for Convective Boundary Layer Height Estimation (SPICER) algorithm that can automatically detect the CBL Height (CBLH) for all of the 159 radar locations across the United States during clear days. The present work is the first step to applying SPICER to a network of Next Generation Radars (NEXRAD) with continuous countrywide coverage. With the possible combination with the Automated Surface Observing System network (ASOS), a source of ceilometer profile data, a validated dataset of CBLH estimates can be expected soon. The algorithm treats averaged differential reflectivity vs range as an image and applies filtering plus Canny edge detection to estimate the CBLH. In addition, another algorithm is presented to automate the detection of the mixing layer height (MLH), a proxy for CBLH from Raman Lidar and a 915 MHz wind profiler. A comparison of CBLH estimates vs widely used methods in meteorology (Radiosondes, Raman Lidar, ceilometer, 915 MHz wind profiler, and Doppler Lidar-based derived Value-Added Product (VAP) ) is performed to validate the NEXRAD detected CBLH using SPICER. The SPICER algorithm shows over 0.9 correlation with radiosonde measurements.
Effectiveness of Ultrathin Al2O3 Capping by Atomic Layer Deposition on the Stability of Single Quantum Dots
(2024-01-01) Sarkar, Yasir; Pelton, Matthew; Physics; Physics
Quantum dots (QDs) possess the capability to function as single photon sources, and their size-dependent optical properties offer a broad range of applications in nanophotonics. However, photo-bleaching and oxidation lead to the degradation of QDs at room temperature, presenting one of the main obstacles to applications. Here, we enhance the stability of single core-shell QDs at room temperature and shield them from the air by using 0.5, 0.7, and 1nm thick capping layers of Al2O3 deposited via atomic layer deposition (ALD). This also enables tip-enhanced strong coupling (TESC) spectroscopy by allowing the formation of a subnanometer plasmonic cavity between a nano-optical antenna and a metal film below the QD. After being exposed to a continuous-wave laser beam of 2.01 mW power for 3.5 hours, photoluminescence (PL) microscopy of QDs under the 0.5nm capping layer demonstrated no reduction in fluorescent QD number compared to a 51% reduction in the number of fluorescent QDs in a sample without such protection. This protection method opens up new possibilities for increasing the fluorescent lifetime of other types of QDs, such as less stable perovskite quantum dots and studying the effect of new capping materials on emitter-plasmon coupling.
Investigating the Properties of Transition Metal-Based Thin Films
(2024-01-01) Chowdhary, Nimarta Kaur; Gougousi, Theodosia; Physics; Physics
Transition metal-based thin films, including oxides and nitrides, are widely studied due to their diverse properties and applications. Among these materials, transition metal oxides (TMOs) are known for their wide-band gaps, high refractive indices, and high transparency in the visible spectrum. Due to their low cost, low toxicity, and high natural abundance, efforts are being made to modify these materials for broader application range, such as visible light absorption. Developing optimal methods for producing and characterizing transition metal-based films remains an ongoing challenge. This research investigates the growth and properties of transition metal-based films using complementary thin film deposition approaches: atomic layer deposition (ALD), and physical vapor deposition (PVD). In this work, ALD thin films were grown by varying parameters such as deposition temperature and purge time. The resulting properties were analyzed using X-ray photoelectron spectroscopy (XPS) for chemical states and composition, Fourier transform infrared spectroscopy (FTIR) for bonding and crystal structure, spectroscopic ellipsometry (SE), and ultraviolet-visible spectroscopy (UV-Vis) foroptical properties, and four-point probe (4PP) for electrical conductivity. This project used a new method of adjusting the ALD deposition process to determine the optical functions, providing a complete picture of the observed properties. ALD-grown hafnium oxide (HfO2) and titanium dioxide (TiO2), grown from similar amine precursors, (X[((CH3)2N)4])X=Hf, Ti with comparable deposition conditions exhibit completely different properties. The properties of ALD TiO2 films are shown to be highly dependent on the processing conditions, particularly in the temperature range within the ‘ALD window’. These films incorporate metallic, carbon, and water-based impurities, resulting in variable optical constants at 633 nm (n = 1.7 – 2.4, k = 0.2 – 1.2) and a wide conductivity range (1000 – 30000 S/m). The properties of the ALD TiO2 films are benchmarked between PVD-grown TiOxNy and PVD TiO2 films, providing further insight into the observed behavior. Conversely, the ALD HfO2 films only incorporate carbon and water-based impurities. The resulting optical constants at 633 nm (n = 1.9 – 2.1, k = 0) and conductivity (400 – 1000 S/m) do not strongly depend on the processing conditions. The results highlight that the underlying ALD chemistry and reaction pathways are significantly more complex than is currently understood and cannot be generalized, even for similar materials. Future investigations require combined experimental, theoretical, and computational approaches. By systematically studying thin film growth using this approach, this research establishes pathways for applications in precursor design, photovoltaics, transparent conductive oxides and optoelectronics.
Temperature-Dependent Properties of Atomic Layer Deposition-Grown TiO2₂Thin Films
(Wiley, 2025-01-07) Chowdhary, Nimarta Kaur; Gougousi, Theodosia
This study investigates the presence of titanium oxynitride bonds in titanium dioxide (TiO₂) thin films grown by atomic layer deposition (ALD) using tetrakis dimethyl amino titanium (TDMAT) and water at temperatures between 150 and 350 °C and its effect on the films’ optical and electrical properties. Compositional analysis using X-ray photoelectron spectroscopy (XPS) reveals increased incorporation of oxynitride bonds as the process temperature increases. Furthermore, depth profile data demonstrates an increase in the abundance of this type of bonding from the surface to the bulk of the films. Ultraviolet-visible spectroscopy (UV-vis) measurements correlate increased visible light absorption for the films with elevated oxynitride incorporation. The optical constants (n, k) of the films show a pronounced dependence on the process temperature that is mirrored in the film conductivity. The detection of oxynitride bonding suggests a secondary reaction pathway in this well-established ALD process chemistry, that may impact film properties. These findings indicate that the choice of process chemistry and conditions can be used to optimize film properties for optoelectronic applications.
Multi-wavelength observations of a jet launch in real time from the post-changing-look Active Galaxy 1ES 1927+654
(2025-01-04) Laha, Sibasish; Meyer, Eileen T.; Sadaula, Dev R.; Ghosh, Ritesh; Sengupta, Dhrubojyoti; Masterson, Megan; Shuvo, Onic Islam; Guainazzi, Matteo; Ricci, Claudio; Begelman, Mitchell C.; Philippov, Alexander; Mbarek, Rostom; Hankla, Amelia M.; Kara, Erin; Panessa, Francesca; Behar, Ehud; Zhang, Haocheng; Pacucci, Fabio; Pal, Main; Ricci, Federica; Villani, Ilaria; Bisogni, Susanna; Franca, Fabio La; Bianchi, Stefano; Bruni, Gabriele; Oates, Samantha; Hahn, Cameron; Nicholl, Matt; Cenko, S. Bradley; Chattopadhyay, Sabyasachi; Gonzalez, Josefa Becerra; Acosta-Pulido, J. A.; Rakshit, Suvendu; Svoboda, Jiri; Gallo, Luigi; Ingram, Adam; Kakkad, Darshan
We present results from a high cadence multi-wavelength observational campaign of the enigmatic changing look AGN 1ES 1927+654 from May 2022- April 2024, coincident with an unprecedented radio flare (an increase in flux by a factor of $\sim 60$ over a few months) and the emergence of a spatially resolved jet at $0.1-0.3$ pc scales (Meyer et al. 2024). Companion work has also detected a recurrent quasi-periodic oscillation (QPO) in the $2-10$ keV band with an increasing frequency ($1-2$ mHz) over the same period (Masterson et al., 2025). During this time, the soft X-rays ($0.3-2$ keV) monotonically increased by a factor of $\sim 8$, while the UV emission remained near-steady with $<30\%$ variation and the $2-10$ keV flux showed variation by a factor $\lesssim 2$. The weak variation of the $2-10$ keV X-ray emission and the stability of the UV emission suggest that the magnetic energy density and accretion rate are relatively unchanged, and that the jet could be launched due to a reconfiguration of the magnetic field (toroidal to poloidal) close to the black hole. Advecting poloidal flux onto the event horizon would trigger the Blandford-Znajek (BZ) mechanism, leading to the onset of the jet. The concurrent softening of the coronal slope (from $\Gamma= 2.70\pm 0.04$ to $\Gamma=3.27\pm 0.04$), the appearance of a QPO, and low coronal temperature ($kT_{e}=8_{-3}^{+8}$ keV) during the radio outburst suggest that the poloidal field reconfiguration can significantly impact coronal properties and thus influence jet dynamics. These extraordinary findings in real time are crucial for coronal and jet plasma studies, particularly as our results are independent of coronal geometry.
Millihertz Oscillations Near the Innermost Orbit of a Supermassive Black Hole
(2025-01-03) Masterson, Megan; Kara, Erin; Panagiotou, Christos; Alston, William N.; Chakraborty, Joheen; Burdge, Kevin; Ricci, Claudio; Laha, Sibasish; Arcavi, Iair; Arcodia, Riccardo; Cenko, S. Bradley; Fabian, Andrew C.; Garc韆, Javier A.; Giustini, Margherita; Ingram, Adam; Kosec, Peter; Loewenstein, Michael; Meyer, Eileen T.; Miniutti, Giovanni; Pinto, Ciro; Remillard, Ronald A.; Sadaula, Dev R.; Shuvo, Onic Islam; Trakhtenbrot, Benny; Wang, Jingyi
Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repetitive events around SMBHs, including the newly-discovered quasi-periodic eruptions (QPEs), are garnering further interest in stellar-mass companions around SMBHs and the progenitors to mHz frequency gravitational wave events. Here we report the discovery of a highly significant mHz Quasi-Periodic Oscillation (QPO) in an actively accreting SMBH, 1ES 1927+654, which underwent a major optical, UV, and X-ray outburst beginning in 2018. The QPO was first detected in 2022 with a roughly 18-minute period, corresponding to coherent motion on scales of less than 10 gravitational radii, much closer to the SMBH than typical QPEs. The period decreased to 7.1 minutes over two years with a decelerating period evolution ($\ddot{P} > 0$). This evolution has never been seen in SMBH QPOs or high-frequency QPOs in stellar mass black holes. Models invoking orbital decay of a stellar-mass companion struggle to explain the period evolution without stable mass transfer to offset angular momentum losses, while the lack of a direct analog to stellar mass black hole QPOs means that many instability models cannot explain all of the observed properties of the QPO in 1ES 1927+654. Future X-ray monitoring will test these models, and if it is a stellar-mass orbiter, the Laser Interferometer Space Antenna (LISA) should detect its low-frequency gravitational wave emission.
XRISM reveals low non-thermal pressure in the core of the hot, relaxed galaxy cluster Abell 2029
(APJ, 2025-01-09) XRISM Collaboration; Boissay-Malaquin, Rozenn; Hamaguchi, Kenji; Hayashi, Takayuki; Mukai, Koji; Pottschmidt, Katja; Tamura, Keisuke; Yaqoob, Tahir
We present XRISM Resolve observations of the core of the hot, relaxed galaxy cluster Abell 2029. We find that the line-of-sight bulk velocity of the intracluster medium (ICM) within the central 180 kpc is at rest with respect to the Brightest Cluster Galaxy, with a 3-sigma upper limit of |v_bulk| < 100 km/s. We robustly measure the field-integrated ICM velocity dispersion to be sigma_v = 169 +/- 10 km/s, obtaining similar results for both single-temperature and two-temperature plasma models to account for the cluster cool core. This result, if ascribed to isotropic turbulence, implies a subsonic ICM with Mach number M_3D ~ 0.21 and a non-thermal pressure fraction of 2%. The turbulent velocity is similar to what was measured in the core of the Perseus cluster by Hitomi, but here in a more massive cluster with an ICM temperature of 7 keV, the limit on non-thermal pressure fraction is even more stringent. Our result is consistent with expectations from simulations of relaxed clusters, but it is on the low end of the predicted distribution, indicating that Abell 2029 is an exceptionally relaxed cluster with no significant impacts from either a recent minor merger or AGN activity.
Dynamic Imprints of Colliding-wind Dust Formation from WR 140
(IOP, 2025-01-13) Lieb, Emma P.; Lau, Ryan M.; Hoffman, Jennifer L.; Corcoran, Michael F.; Garcia Marin, Macarena; Gull, Theodore R.; Hamaguchi, Kenji; Han, Yinuo; Hankins, Matthew J.; Jones, Olivia C.; Madura, Thomas I.; Marchenko, Sergey V.; Matsuhara, Hideo; Millour, Florentin; Moffat, Anthony F. J.; Morris, Mark R.; Morris, Patrick W.; Onaka, Takashi; Perrin, Marshall D.; Rest, Armin; Richardson, Noel; Russell, Christopher M. P.; Sanchez-Bermudez, Joel; Soulain, Anthony; Tuthill, Peter; Weigelt, Gerd; Williams, Peredur M.
Carbon-rich Wolf–Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The "textbook" example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among the first to utilize two separate JWST observations, from Cycle 1 ERS (2022 July) and Cycle 2 (2023 September), to measure WR 140's dust kinematics and confirm its morphology. To measure the proper motions and projected velocities of the dust shells, we performed a novel point-spread function (PSF) subtraction to reduce the effects of the bright diffraction spikes and carefully aligned the Cycle 2 to the Cycle 1 images. At 7.7 μm, through the bright feature common to 16 dust shells (C1), we find an average dust shell proper motion of 390 ± 29 mas yr⁻¹, which equates to a projected velocity of 2714 ± 188 km s⁻¹ at a distance of 1.64 kpc. Our measured speeds are constant across all visible shells and consistent with previously reported dust expansion velocities. Our observations not only prove that these dusty shells are astrophysical (i.e., not associated with any PSF artifact) and originate from WR 140, but also confirm the "clumpy" morphology of the dust shells, in which identifiable substructures within certain shells persist for at least 14 months from one cycle to the next. These results support the hypothesis that clumping in the wind collision region is required for dust production in WR binaries.
Power of simultaneous X-ray and ultraviolet high-resolution spectroscopy for probing outflows in active galactic nuclei
(SPIE, 2024-12) Mehdipour, Missagh; Brenneman, Laura W.; Miller, Jon M.; Costantini, Elisa; Behar, Ehud; Gallo, Luigi; Kaastra, Jelle S.; Laha, Sibasish; Nowak, Michael A.
Black hole accretion in active galactic nuclei (AGN) is coupled to the evolution of their host galaxies. Outflowing winds in AGN can play an important role in this evolution through the resulting feedback mechanism. Multi-wavelength spectroscopy is key for probing the intertwined physics of inflows and outflows in AGN. However, with the current spectrometers, crucial properties of the ionized outflows are poorly understood, such as their coupling to accretion rate, their launching mechanism, and their kinetic power. We discuss the need for simultaneous X-ray and UV high-resolution spectroscopy for tackling outstanding questions on these outflows in AGN. The instrumental requirements for achieving the scientific objectives are addressed. We demonstrate that these requirements would be facilitated by the proposed Arcus Probe mission concept. The multi-wavelength spectroscopy and timing by Arcus would enable us to establish the kinematics and ionization structure of the entire ionized outflow, extending from the vicinity of the accretion disk to the outskirts of the host galaxy. Arcus would provide key diagnostics on the origin, driving mechanism, and energetics of the outflows, which are useful benchmarks for testing various theoretical models of outflows and understanding their impact in AGN.
Overionized plasma in the supernova remnant Sagittarius A East anchored by XRISM observations
(Oxford University Press, 2024-12-26) Boissay-Malaquin, Rozenn; Hamaguchi, Kenji; Hayashi, Takayuki; Mukai, Koji; Pottschmidt, Katja; Tamura, Keisuke; Yaqoob, Tahir; XRISM Collaboration
Sagittarius A East is a supernova remnant with a unique surrounding environment, as it is located in the immediate vicinity of the supermassive black hole at the Galactic center, Sagittarius A*. The X-ray emission of the remnant is suspected to show features of overionized plasma, which would require peculiar evolutionary paths. We report on the first observation of Sagittarius A East with the X-Ray Imaging and Spectroscopy Mission (XRISM). Equipped with a combination of a high-resolution microcalorimeter spectrometer and a large field-of-view CCD imager, we for the first time resolved the Fe xxv K-shell lines into fine structure lines and measured the forbidden-to-resonance intensity ratio to be 1.39 ± 0.12, which strongly suggests the presence of overionized plasma. We obtained a reliable constraint on the ionization temperature just before the transition into the overionization state, of >4 keV. The recombination timescale was constrained to be <8 × 10¹¹ cm⁻³ s. The small velocity dispersion of 109 ± 6 km s⁻¹ indicates a low Fe ion temperature <8 keV and a small expansion velocity <200 km s⁻¹. The high initial ionization temperature and small recombination timescale suggest that either rapid cooling of the plasma via adiabatic expansion from dense circumstellar material or intense photoionization by Sagittarius A∗ in the past may have triggered the overionization.
Extracting the Optical Constants of Partially Absorbing TiO2 ALD Films
(MDPI, 2024-12-12) Chowdhary, Nimarta Kaur; Gougousi, Theodosia
Typical titanium oxide (TiO₂) films are transparent in the visible range, allowing for their index of refraction and thickness to be extracted by single-angle spectroscopic ellipsometry (SE) using a Cauchy model. However, TiO₂ films grown by atomic layer deposition (ALD) from tetrakis(dimethylamino)titanium (IV) (TDMAT) and H₂O at 350 °C absorb in the visible range due to the formation of Ti-O-N/Ti-N bonds. Single-angle SE is inadequate for extracting the optical constants of these films, as there are more unknowns (n, k, d) than measurable parameters (ψ, Δ). To overcome this limitation, we combined SE with transmission (T) measurements, a method known as SE + T. In the process, we developed an approach to prevent backside deposition on quartz substrates during ALD deposition. When applying a B-spline model to SE + T data, the film thicknesses on the quartz substrates closely matched those on companion Si samples measured via standard lithography. The resulting optical constants indicate a reduced refractive index, n, and increased extinction coefficient, k, when compared to purer TiO₂ thin films deposited via a physical vapor deposition (PVD) method, reflecting the influence of nitrogen incorporation on the optical properties.
X-ray properties of coronal emission in radio quiet Active Galactic Nuclei
(2024-12-20) Laha, Sibasish; Ricci, Claudio; Mather, John C.; Behar, Ehud; Gallo, Luigi C.; Marin, Frederic; Mbarek, Rostom; Hankla, Amelia
Active galactic nuclei (AGN) are powerful sources of panchromatic radiation. All AGN emit in X-rays, contributing around ∼5−10% of the AGN bolometric luminosity. The X-ray emitting region, popularly known as the corona, is geometrically and radiatively compact with a size typically ≲10RG (gravitational radii). The rapid and extreme variability in X-rays also suggest that the corona must be a dynamic structure. Decades of X-ray studies have shed much light on the topic, but the nature and origin of AGN corona are still not clearly understood. This is mostly due to the complexities involved in several physical processes at play in the high-gravity, high-density and high-temperature region in the vicinity of the supermassive black hole (SMBH). It is still not clear how exactly the corona is energetically and physically sustained near a SMBH. The ubiquity of coronal emission in AGN points to their fundamental role in black hole accretion processes. In this review we discuss the X-ray observational properties of corona in radio quiet AGN.
Time transfer and clock synchronization with ghost frequency comb
(AIP, 2024-12-10) Joshi, Binod; Smith, Thomas A.; Shih, Yanhua
We report an experimental demonstration of a time transfer and distant clock synchronization scheme based on what we have labeled as a ghost frequency comb, observed from the nonlocal correlation measurements of a laser beam. Unlike a conventional frequency comb, the laser beam used in this work does not consist of a pulse train but instead it is in a continuous-wave operation. The laser beam, consisting of half a million longitudinal cavity modes from a fiber ring laser, is split into two beams, each sent to a distant observer. In their local measurements, both observers observe constant intensity with no pulse structure present. Surprisingly, a pulse train of comb-like, ultra-narrow peaks is observed from their nonlocal correlation function measurement. This observation makes an important contribution to the field of precision spectroscopy, as we show in optical correlation-based nonlocal timing and positioning.
The XRISM/Resolve View of the Fe K Region of Cyg X-3
(IOP Science, 2024-12) XRISM Collaboration; Audard, Marc; Awaki, Hisamitsu; Ballhausen, Ralf; Bamba, Aya; Behar, Ehud; Boissay-Malaquin, Rozenn; Brenneman, Laura; Brown, Gregory V.; Corrales, Lia; Costantini, Elisa; Cumbee, Renata; Trigo, Mar韆 D韆z; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Eckert, Dominique; Eguchi, Satoshi; Enoto, Teruaki; Ezoe, Yuichiro; Foster, Adam; Fujimoto, Ryuichi; Fujita, Yutaka; Fukazawa, Yasushi; Fukushima, Kotaro; Furuzawa, Akihiro; Gallo, Luigi; Garc韆, Javier A.; Gu, Liyi; Guainazzi, Matteo; Hagino, Kouichi; Hamaguchi, Kenji; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hell, Natalie; Hodges-Kluck, Edmund; Hornschemeier, Ann; Ichinohe, Yuto; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Kaastra, Jelle; Kallman, Timothy; Kara, Erin; Katsuda, Satoru; Kanemaru, Yoshiaki; Kelley, Richard; Kilbourne, Caroline; Kitamoto, Shunji; Kobayashi, Shogo; Kohmura, Takayoshi; Kubota, Aya; Leutenegger, Maurice; Loewenstein, Michael; Maeda, Yoshitomo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian; Mernier, Fran鏾is; Miller, Eric D.; Miller, Jon M.; Mitsuishi, Ikuyuki; Mizumoto, Misaki; Mizuno, Tsunefumi; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard; Nakajima, Hiroshi; Nakazawa, Kazuhiro; Ness, Jan-Uwe; Nobukawa, Kumiko; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ogawa, Shoji; Ogorzalek, Anna; Okajima, Takashi; Ota, Naomi; Paltani, Stephane; Petre, Robert; Plucinsky, Paul; Porter, Frederick S.; Pottschmidt, Katja; Sato, Kosuke; Sato, Toshiki; Sawada, Makoto; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall; Suzuki, Hiromasa; Szymkowiak, Andrew; Takahashi, Hiromitsu; Takeo, Mai; Tamagawa, Toru; Tamura, Keisuke; Tanaka, Takaaki; Tanimoto, Atsushi; Tashiro, Makoto; Terada, Yukikatsu; Terashima, Yuichi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi; Uchida, Hiroyuki; Uchida, Nagomi; Uchida, Yuusuke; Uchiyama, Hideki; Ueda, Yoshihiro; Uno, Shinichiro; Vink, Jacco; Watanabe, Shin; Williams, Brian J.; Yamada, Satoshi; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yoneyama, Tomokage; Yoshida, Tessei; Yukita, Mihoko; Zhuravleva, Irina; Tomaru, Ryota; Hayashi, Tasuku; Hakamata, Tomohiro; Miura, Daiki; Koljonen, Karri; McCollough, Mike
The X-ray binary system Cygnus X-3 (4U 2030+40, V1521 Cyg) is luminous but enigmatic owing to the high intervening absorption. High-resolution X-ray spectroscopy uniquely probes the dynamics of the photoionized gas in the system. In this Letter, we report on an observation of Cyg X-3 with the XRISM/Resolve spectrometer, which provides unprecedented spectral resolution and sensitivity in the 2� keV band. We detect multiple kinematic and ionization components in absorption and emission whose superposition leads to complex line profiles, including strong P Cygni profiles on resonance lines. The prominent Fe xxv He? and Fe xxvi Ly? emission complexes are clearly resolved into their characteristic fine-structure transitions. Self-consistent photoionization modeling allows us to disentangle the absorption and emission components and measure the Doppler velocity of these components as a function of binary orbital phase. We find a significantly higher velocity amplitude for the emission lines than for the absorption lines. The absorption lines generally appear blueshifted by ??500�0 km s?1. We show that the wind decomposes naturally into a relatively smooth and large-scale component, perhaps associated with the background wind itself, plus a turbulent, denser structure located close to the compact object in its orbit.
NEWS Integrated Analysis (NEWS-IA) Dataset: Budgets and Input Data
(NTRS, 2024-11-20) Roberts, J. Brent; Olson, William S.
This documentation provides a summary of the underlying physical and mathematical descriptions of the global energy and water cycle budgets used to produce the NASA Energy and Water Cycle Study (NEWS) Integrated Analysis. In addition to discussion of the budget equations, a summary is provided concerning NEWS regions, input data sources, and data fields found in the NEWS-IA input data file.
Enhanced zero-phonon line emission from an ensemble of W centers in circular and bowtie Bragg grating cavities
(De Gruyter, 2024-11-19) Veetil, Vijin Kizhake; Song, Junyeob; Namboodiri, Pradeep N.; Ebadollahi, Nikki; Chanana, Ashish; Katzenmeyer, Aaron M.; Pederson, Christian; Pomeroy, Joshua M.; Chiles, Jeffrey; Shainline, Jeffrey; Srinivasan, Kartik; Davanco, Marcelo; Pelton, Matthew
Color centers in silicon have recently gained considerable attention as single-photon sources and as spin qubit-photon interfaces. However, one of the major bottlenecks to the application of silicon color centers is their low overall brightness due to a relatively slow emission rate and poor light extraction from silicon. Here, we increase the photon collection efficiency from an ensemble of a particular kind of color center, known as W centers, by embedding them in circular Bragg grating cavities resonant with their zero-phonon-line emission. We observe a ≈5-fold enhancement in the photon collection efficiency (the fraction of photons extracted from the sample and coupled into a single-mode fiber), corresponding to an estimated ≈11-fold enhancement in the photon extraction efficiency (the fraction of photons collected by the first lens above the sample). For these cavities, we observe lifetime reduction by a factor of ≈1.3 . For W centers in resonant bowtie-shaped cavities, we observed a ≈3-fold enhancement in the photon collection efficiency, corresponding to a ≈6-fold enhancement in the photon extraction efficiency, and observed a lifetime reduction factor of ≈1.1 . The bowtie cavities thus preserve photon collection efficiency and Purcell enhancement comparable to circular cavities while providing the potential for utilizing in-plane excitation methods to develop a compact on-chip light source.
Improved characterization of Dome Concordia for tracking calibration changes in MODIS reflective solar bands
(SPIE, 2024-11-20) McBride, Brent; Twedt, Kevin; Wu, Aisheng; Geng, Xu; Xiong, Xiaoxiong
Dome Concordia (Dome C) in Antarctica is an excellent calibration site for polar-orbiting Earth observation instruments due to its spectral, spatial, and temporal uniformity. These instruments also observe Dome C multiple times a day and at a variety of geometries. The MODIS Characterization Support Team uses regular observations of Dome C by Aqua and Terra MODIS to help validate and improve the calibration of the detector gain and response versus scan angle of the reflective solar bands used to generate NASA’s Level 1B reflectance products. The reflectance trends at Dome C are typically assessed on a yearly basis, due to a six-month sunlit observation period. In this work, we increase the temporal resolution of the trends from yearly to bi-monthly and reduce measurement noise using a reflectance-based snow BRDF model. We show results for Terra and Aqua MODIS BRDF-normalized reflectance using the Collection 7 calibration for bands 1-4, 8-9, and 17. The BRDF model significantly reduces the variations in the bi-monthly reflectance trends with the best results observed near nadir and for the blue bands 3, 8, and 9. The higher temporal sampling allows for better real-time identification of any calibration errors during the sunlit season. In addition, due to its polar location, Dome C is largely insensitive to the recent orbit drift of the Terra and Aqua satellites which has created challenges for MODIS calibration based on other on-board and Earth targets. Combined, these advantages will make Dome C a particularly important calibration reference target during the final years of the Terra and Aqua missions.
In-flight characterization of the Hyper-Angular Rainbow Polarimeter (HARP2) on the NASA PACE mission
(SPIE, 2024-11-20) McBride, Brent; Sienkiewicz, Noah; Xu, Xiaoguang; Puthukkudy, Anin; Fernandez-Borda, Roberto; Martins, J. Vanderlei
The Hyper-Angular Rainbow Polarimeter (HARP2) is a novel wide-field of view imaging polarimeter instrument on the recently-launched NASA Plankton Aerosol Cloud ocean Ecosystem (PACE) mission. Since launch on February 8 2024, HARP2 has taken over 6 months of global Earth data. In order for this data to meet scientific quality standards, we must ensure that it is as accurate as possible and over long periods of time. We use well-characterized Earth targets, such as Saharan deserts, as well as regular views of the Sun and dark frames to trend our on-orbit calibration. In this work, we discuss the preliminary performance trends derived from these activities and how well they compare with the HARP2 prelaunch calibration.
First results and on-orbit performance of the Hyper-Angular Rainbow Polarimeter (HARP2) on the PACE satellite
(SPIE, 2024-11-20) Martins, J. Vanderlei; Fernandez-Borda, Roberto; Puthukkudy, Anin; Xu, Xiaoguang; Sienkiewicz, Noah; Smith, Rachel; McBride, Brent; Dubovik, Oleg; Remer, Lorraine
The Hyper-Angular Rainbow Polarimeter-2 (HARP2) was launched on board the Plankton, Aerosol, Cloud and ocean Ecosystem (PACE) mission, in February 2024, for the global measurement of aerosol and cloud properties as well as to provide atmospheric correction over the footprint of the Ocean Color Instrument (OCI). HARP2 is designed to collect data over a wide field of view in the cross-track direction (+/-47deg) allowing for global coverage in about two days, as well as an even wider field of view in the along-track direction (+/-54deg) providing measurements over a wide range of scattering angles. HARP2 samples 10 angles at 440, 550, and 870nm focusing on aerosol and surface retrievals, and up to 60 angles at 670nm for the hyper-angular retrieval of cloud microphysical properties. The HARP2 instrument collects three nearly identical images with linear polarizers aligned at 0°, 45°, and 90° that can be converted to push-broom images of the I, Q, and U Stokes parameters for each angle, and each wavelength. The HARP2 technology was first demonstrated with the HARP CubeSat satellite which collected a limited dataset for 2 years from 2020 to 2022. HARP2 extends these measurements to a full global coverage in two days, seven days a week.

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