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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Magneto-optics in a van der Waals magnet tuned by self-hybridized polaritons
(Springer Nature, 2023-08) Dirnberger, Florian; Quan, Jiamin; Bushati, Rezlind; Diederich, Geoffrey M.; Florian, Matthias; Klein, Julian; Mosina, Kseniia; Sofer, Zdenek; Xu, Xiaodong; Kamra, Akashdeep; Garc�a-Vidal, Francisco J.; Al�, Andrea; Menon, Vinod M.
Controlling quantum materials with light is of fundamental and technological importance. By utilizing the strong coupling of light and matter in optical cavities1?3, recent studies were able to modify some of their most defining features4?6. Here we study the magneto-optical properties of a van der Waals magnet that supports strong coupling of photons and excitons even in the absence of external cavity mirrors. In this material?the layered magnetic semiconductor CrSBr?emergent light?matter hybrids called polaritons are shown to substantially increase the spectral bandwidth of correlations between the magnetic, electronic and optical properties, enabling largely tunable optical responses to applied magnetic fields and magnons. Our results highlight the importance of exciton?photon self-hybridization in van der Waals magnets and motivate novel directions for the manipulation of quantum material properties by strong light?matter coupling.
Unifying radiative transfer models in computer graphics and remote sensing, Part II: A differentiable, polarimetric forward model and validation
(Elsevier, 2024-01-03) Salesin, Katherine; Knobelspiesse, Kirk D.; Chowdhary, Jacek; Zhai, Peng-Wang; Jarosz, Wojciech
The constellation of Earth-observing satellites continuously collects measurements of scattered radiance, which must be transformed into geophysical parameters in order to answer fundamental scientific questions about the Earth. Retrieval of these parameters requires highly flexible, accurate, and fast forward and inverse radiative transfer models. Existing forward models used by the remote sensing community are typically accurate and fast, but sacrifice flexibility by assuming the atmosphere or ocean is composed of plane-parallel layers. Monte Carlo forward models can handle more complex scenarios such as 3D spatial heterogeneity, but are relatively slower. We propose looking to the computer graphics community for inspiration to improve the statistical efficiency of Monte Carlo forward models and explore new approaches to inverse models for remote sensing. In Part 2 of this work, we demonstrate that Monte Carlo forward models in computer graphics are capable of sufficient accuracy for remote sensing by extending Mitsuba 3, a forward and inverse modeling framework recently developed in the computer graphics community, to simulate simple atmosphere-ocean systems and show that our framework is capable of achieving error on par with codes currently used by the remote sensing community on benchmark results.
Unifying radiative transfer models in computer graphics and remote sensing, Part I: A survey
(Elsevier, 2023-12-02) Salesin, Katherine; Knobelspiesse, Kirk D.; Chowdhary, Jacek; Zhai, Peng-Wang; Jarosz, Wojciech
The constellation of Earth-observing satellites continuously collects measurements of scattered radiance, which must be transformed into geophysical parameters in order to answer fundamental scientific questions about the Earth. Retrieval of these parameters requires highly flexible, accurate, and fast forward and inverse radiative transfer models. Existing forward models used by the remote sensing community are typically accurate and fast, but sacrifice flexibility by assuming the atmosphere or ocean is composed of plane-parallel layers. Monte Carlo forward models can handle more complex scenarios such as 3D spatial heterogeneity, but are relatively slower. We propose looking to the computer graphics community for inspiration to improve the statistical efficiency of Monte Carlo forward models and explore new approaches to inverse models for remote sensing. In Part 1 of this work, we examine the evolution of radiative transfer models in computer graphics and highlight recent advancements that have the potential to push forward models in remote sensing beyond their current periphery of realism.
The bulk motion of gas in the core of the Centaurus galaxy cluster
(Nature, 2025-02) Audard, Marc; Awaki, Hisamitsu; Ballhausen, Ralf; Bamba, Aya; Behar, Ehud; Boissay-Malaquin, Rozenn; Brenneman, Laura; Brown, Gregory V.; Corrales, Lia; Costantini, Elisa; Cumbee, Renata; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Eckert, Dominique; Enoto, Teruaki; Eguchi, Satoshi; Ezoe, Yuichiro; Foster, Adam; Fujimoto, Ryuichi; Fujita, Yutaka; Fukazawa, Yasushi; Fukushima, Kotaro; Furuzawa, Akihiro; Gallo, Luigi; Garc�a, 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�ois; 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 Scott; 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; Trigo, Mar�a D�az; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi G.; 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 Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yoneyama, Tomokage; Yoshida, Tessei; Yukita, Mihoko; Zhuravleva, Irina; Kondo, Marie; Werner, Norbert; Pl?ek, Tom�?; Sun, Ming; Hosogi, Kokoro; Majumder, Anwesh; XRISM collaboration
Galaxy clusters contain vast amounts of hot ionized gas known as the intracluster medium (ICM). In relaxed cluster cores, the radiative cooling time of the ICM is shorter than the age of the cluster. However, the absence of line emission associated with cooling suggests heating mechanisms that offset the cooling, with feedback from active galactic nuclei (AGNs) being the most likely source1,2. Turbulence and bulk motions, such as the oscillating (?sloshing?) motion of the core gas in the cluster potential well, have also been proposed as mechanisms for heat distribution from the outside of the core3,4. Here we present X-ray spectroscopic observations of the Centaurus galaxy cluster with the X-Ray Imaging and Spectroscopy Mission satellite. We find that the hot gas flows along the line of sight relative to the central galaxy, with velocities from 130?km?s?1 to 310?km?s?1 within about�30?kpc of the centre. This indicates bulk flow consistent with core gas sloshing. Although the bulk flow may prevent excessive accumulation of cooled gas at the centre, it could distribute the heat injected by the AGN and bring in thermal energy from the surrounding ICM. The velocity dispersion of the gas is found to be only ?120?km?s?1 in the core, even within about 10?kpc of the AGN. This suggests that the influence of the AGN on the surrounding ICM motion is limited in the cluster.
Machine learning based aerosol and ocean color joint retrieval algorithm for multiangle polarimeters over coastal waters
(Optica Publishing Group, 2024-08-05) Aryal, Kamal; Zhai, Peng-Wang; Gao, Meng; Franz, Bryan A.; Knobelspiesse, Kirk; Hu, Yongxiang
NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, recently launched in February 2024, carries two multiangle polarimeters (MAPs): the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and SRON Spectropolarimeter for Planetary Exploration One (SPEXone). Measurements from these MAPs will greatly advance ocean ecosystem and aerosol studies as their measurements contain rich information on the microphysical properties of aerosols and hydrosols. The Multi-Angular Polarimetric Ocean coLor (MAPOL) joint retrieval algorithm has been developed to retrieve aerosol and ocean color information, which uses a vector radiative transfer (RT) model as the forward model. The RT model is computationally expensive, which makes processing a large amount of data challenging. FastMAPOL was developed to expedite retrieval using neural networks to replace the RT forward models. As a prototype study, FastMAPOL was initially limited to open ocean applications where the ocean Inherent Optical Properties (IOPs) were parameterized in terms of one parameter: chlorophyll-a concentration (Chla). In this study we further expand the FastMAPOL joint retrieval algorithm to incorporate NN based forward models for coastal waters, which use multi-parameter bio-optical models. In addition, aerosols are represented by six components, i.e., fine mode non absorbing insoluble (FNAI), brown carbon (BrC), black carbon (BC), fine mode non absorbing soluble (FNAS), sea salt (SS) and non-spherical dust (Dust). Sea salt and dust are coarse mode aerosols, while the other components are fine mode. The sizes and spectral refractive indices are fixed for each aerosol component, while their abundances are retrievable. The multi-parameter bio-optical model and aerosol components are chosen to represent the coastal marine environment. The retrieval algorithm is applied to synthetic measurements in three different configurations of MAPs in the PACE mission: HARP2 observations only, SPEXone observations only and combined HARP2 and SPEXone observations. The retrieval results from synthetic measurements show that for aerosol retrieval the SPEXone-only configuration works equally well with the HAPR2-only configuration. On the other hand, for ocean color retrieval the SPEXone instrument provides better information due to its larger spectral coverage. For the surface parameters (wind speed), HARP2 measurements provide better information due to its wide field of view. Combined measurement configuration HARP2+SPEXone performed the best to retrieve all aerosol, ocean color, and surface parameters. We also studied the impact of sun glint to aerosol and ocean color retrievals. The retrieval test revealed that wind speed and absorbing aerosol retrieval improves significantly when including measurements at glint geometries. Furthermore, the retrieval algorithm is equipped with modules for atmospheric correction and bidirectional reflectance distribution (BRDF) correction to obtain the remote sensing reflectance, which enables ocean biogeochemistry studies using the PACE polarimeter data.
Strain-programmable van der Waals magnetic tunnel junctions
(2023-01-10) Cenker, John; Ovchinnikov, Dmitry; Yang, Harvey; Chica, Daniel G.; Zhu, Catherine; Cai, Jiaqi; Diederich, Geoffrey M.; Liu, Zhaoyu; Zhu, Xiaoyang; Roy, Xavier; Cao, Ting; Daniels, Matthew W.; Chu, Jiun-Haw; Xiao, Di; Xu, Xiaodong
The magnetic tunnel junction (MTJ) is a backbone device for spintronics. Realizing next generation energy efficient MTJs will require operating mechanisms beyond the standard means of applying magnetic fields or large electrical currents. Here, we demonstrate a new concept for programmable MTJ operation via strain control of the magnetic states of CrSBr, a layered antiferromagnetic semiconductor used as the tunnel barrier. Switching the CrSBr from antiferromagnetic to ferromagnetic order generates a giant tunneling magnetoresistance ratio without external magnetic field at temperatures up to ~ 140 K. When the static strain is set near the phase transition, applying small strain pulses leads to active flipping of layer magnetization with controlled layer number and thus magnetoresistance states. Further, finely adjusting the static strain to a critical value turns on stochastic switching between metastable states, with a strain-tunable sigmoidal response curve akin to the stochastic binary neuron. Our results highlight the potential of strain-programmable van der Waals MTJs towards spintronic applications, such as magnetic memory, random number generation, and probabilistic and neuromorphic computing.
Tunable interaction between excitons and hybridized magnons in a layered semiconductor
(Springer Nature, 2022-28-12) Diederich, Geoffrey M.; Cenker, John; Ren, Yafei; Fonseca, Jordan; Chica, Daniel G.; Bae, Youn Jue; Zhu, Xiaoyang; Roy, Xavier; Cao, Ting; Xiao, Di; Xu, Xiaodong
The interaction between distinct excitations in solids is of both fundamental interest and technological importance. One such interaction is the coupling between an exciton, a Coulomb bound electron?hole pair, and a magnon, a collective spin excitation. The recent emergence of van der Waals magnetic semiconductors1 provides a platform to explore these exciton?magnon interactions and their fundamental properties, such as strong correlation2, as well as their photospintronic and quantum transduction3 applications. Here we demonstrate the precise control of coherent exciton?magnon interactions in the layered magnetic semiconductor CrSBr. We varied the direction of an applied magnetic field relative to the crystal axes, and thus the rotational symmetry of the magnetic system4. Thereby, we tuned not only the exciton coupling to the bright magnon, but also to an optically dark mode via magnon?magnon hybridization. We further modulated the exciton?magnon coupling and the associated magnon dispersion curves through the application of uniaxial strain. At a critical strain, a dispersionless dark magnon band emerged. Our results demonstrate an unprecedented level of control of the opto?mechanical?magnonic coupling, and a step towards the predictable and controllable implementation of hybrid quantum magnonics5?11.
Electrical, optical, and magnetic properties of amorphous yttrium iron oxide thin films and consequences for non-local resistance measurements
(AIP, 2023-06-08) Roos, M. J.; Bleser, S. M.; Hernandez, L.; Diederich, Geoffrey M.; Siemens, M. E.; Wu, M.; Kirby, B. J.; Zink, B. L.
We present magnetic characterization, charge resistivity, and optical photoluminescence measurements on amorphous yttrium iron oxide thin films ( a-Y?Fe?O), with supporting comparisons to amorphous germanium ( a-Ge) films. We measured magnetic properties with both SQUID magnetometry and polarized neutron reflectometry. These results not only confirm that a-Y?Fe?O is a disordered magnetic material with strong predominantly antiferromagnetic exchange interactions and a high degree of frustration, but also that it is best understood electrically as a disordered semiconductor. As with amorphous germanium, a-Y?Fe?O obeys expectations for variable-range hopping through localized electron states over a wide range of temperature. We also clarify the consequences of charge transport through such a semiconducting medium for non-local voltage measurements intended to probe spin transport in nominally insulating magnetic materials. We further compare non-local resistance measurements made with ?quasi-dc? automated current reversal to ac measurements made with a lock-in amplifier. These show that the ?quasi-dc? measurement has an effective ac current excitation with frequency up to approximately 22?Hz, and that this effective ac excitation can cause artifacts in these measurements including incorrect sign of the non-local resistance. This comprehensive investigation of non-local resistance measurements in a-Y?Fe?O shows no evidence of spin transport on micrometer length scales, which is contrary to our original work, and in line with more recent investigations by other groups.
VERITAS and multiwavelength observations of the Blazar B3 2247+381 in response to an IceCube neutrino alert
(2025-02-06) Acharyya, Atreya; Adams, Colin B.; Bangale, Priyadarshini; Bartkoske, J. T.; Benbow, Wystan; Buckley, James H.; Chen, Yu; Christiansen, Jodi; Chromey, Alisha; Duerr, Anne; Errando, Manel; Godoy, Miguel E.; Falcone, Abe; Feng, Qi; Foote, Juniper; Fortson, Lucy; Furniss, Amy; Hanlon, William; Hanna, David; Hervet, Olivier; Hinrichs, Claire E.; Holder, Jamie; Humensky, Thomas B.; Jin, Weidong; Johnson, Madalyn N.; Kaaret, Philip; Kertzman, Mary P.; Kherlakian, Maria; Kieda, David; Kleiner, Tobias K.; Korzoun, Mx Nikolas; Krennrich, Frank; Kumar, Sajan; Lang, Mark J.; Lundy, Matthew; McGrath, Conor; Meyer, Eileen T.; Millard, Matthew J.; Millis, John; Mooney, Connor; Moriarty, Patrick; Mukherjee, Reshmi; Ning, Wenmeng; O'Brien, Stephan; Ong, Rene A.; Pohl, Martin; Pueschel, Elisa; Quinn, John; Rabinowitz, Pazit L.; Ragan, Ken; Reynolds, Paul; Ribeiro, Deivid; Roache, Emmet Thomas; Ryan, Jamie L.; Sadeh, Iftach; Sadun, Alberto; Saha, Lab; Santander, Marcos; Sembroski, Glenn H.; Shang, Ruo-Yu; Splettstoesser, Megan; Tak, Donggeun; Talluri, Anjana K.; Tucci, James V.; Valverde, Janeth; Williams, David A.; Wong, Sam L.; Woo, Jooyun; Abbasi, R.; Ackermann, M.; Adams, J.; Agarwalla, S. K.; Aguilar, J. A.; Ahlers, M.; Alameddine, J. M.; Amin, N. M.; Andeen, K.; Argüelles, C.; Ashida, Y.; Athanasiadou, S.; Axani, S. N.; Babu, R.; Bai, X.; V, A. Balagopal; Baricevic, M.; Barwick, S. W.; Bash, S.; Basu, V.; Bay, R.; Beatty, J. J.; Tjus, J. Becker; Beise, J.; Bellenghi, C.; BenZvi, S.; Berley, D.; Bernardini, E.; Besson, D. Z.; Blaufuss, E.; Bloom, L.; Blot, S.; Bontempo, F.; Motzkin, J. Y. Book; Meneguolo, C. Boscolo; Böser, S.; Botner, O.; Böttcher, J.; Braun, J.; Brinson, B.; Brisson-Tsavoussis, Z.; Brostean-Kaiser, J.; Brusa, L.; Burley, R. T.; Butterfield, D.; Campana, M. A.; Caracas, I.; Carloni, K.; Carpio, J.; Chattopadhyay, S.; Chau, N.; Chen, Z.; Chirkin, D.; Choi, S.; Clark, B. A.; Coleman, A.; Coleman, P.; Collin, G. H.; Connolly, A.; Conrad, J. M.; Corley, R.; Cowen, D. F.; Clercq, C. De; DeLaunay, J. J.; Delgado, D.; Deng, S.; Desai, A.; Desiati, P.; Vries, K. D. de; Wasseige, G. de; DeYoung, T.; Diaz, A.; Díaz-Vélez, J. C.; Dierichs, P.; Dittmer, M.; Domi, A.; Draper, L.; Dujmovic, H.; Durnford, D.; Dutta, K.; DuVernois, M. A.; Ehrhardt, T.; Eidenschink, L.; Eimer, A.; Eller, P.; Ellinger, E.; Mentawi, S. El; Elsässer, D.; Engel, R.; Erpenbeck, H.; Esmail, W.; Evans, J.; Evenson, P. A.; Fan, K. L.; Fang, K.; Farrag, K.; Fazely, A. R.; Fedynitch, A.; Feigl, N.; Fiedlschuster, S.; Finley, C.; Fischer, L.; Fox, D.; Franckowiak, A.; Fukami, S.; Fürst, P.; Gallagher, J.; Ganster, E.; Garcia, A.; Garcia, M.; Garg, G.; Genton, E.; Gerhardt, L.; Ghadimi, A.; Girard-Carillo, C.; Glaser, C.; Glüsenkamp, T.; Gonzalez, J. G.; Goswami, S.; Granados, A.; Grant, D.; Gray, S. J.; Griffin, S.; Griswold, S.; Groth, K. M.; Guevel, D.; Günther, C.; Gutjahr, P.; Ha, C.; Haack, C.; Hallgren, A.; Halve, L.; Halzen, F.; Hamacher, L.; Hamdaoui, H.; Minh, M. Ha; Handt, M.; Hanson, K.; Hardin, J.; Harnisch, A. A.; Hatch, P.; Haungs, A.; Häußler, J.; Helbing, K.; Hellrung, J.; Hermannsgabner, J.; Heuermann, L.; Heyer, N.; Hickford, S.; Hidvegi, A.; Hill, C.; Hill, G. C.; Hmaid, R.; Hoffman, K. D.; Hori, S.; Hoshina, K.; Hostert, M.; Hou, W.; Huber, T.; Hultqvist, K.; Hünnefeld, M.; Hussain, R.; Hymon, K.; Ishihara, A.; Iwakiri, W.; Jacquart, M.; Jain, S.; Janik, O.; Jansson, M.; Jeong, M.; Jin, M.; Jones, B. J. P.; Kamp, N.; Kang, D.; Kang, W.; Kang, X.; Kappes, A.; Kappesser, D.; Kardum, L.; Karg, T.; Karl, M.; Karle, A.; Katil, A.; Katz, U.; Kauer, M.; Kelley, J. L.; Khanal, M.; Zathul, A. Khatee; Kheirandish, A.; Kiryluk, J.; Klein, S. R.; Kobayashi, Y.; Kochocki, A.; Koirala, R.; Kolanoski, H.; Kontrimas, T.; Köpke, L.; Kopper, C.; Koskinen, D. J.; Koundal, P.; Kowalski, M.; Kozynets, T.; Krieger, N.; Krishnamoorthi, J.; Krishnan, T.; Kruiswijk, K.; Krupczak, E.; Kumar, A.; Kun, E.; Kurahashi, N.; Lad, N.; Gualda, C. Lagunas; Lamoureux, M.; Larson, M. J.; Lauber, F.; Lazar, J. P.; DeHolton, K. Leonard; Leszczy?ska, A.; Liao, J.; Lincetto, M.; Liu, Y. T.; Liubarska, M.; Love, C.; Lu, L.; Lucarelli, F.; Luszczak, W.; Lyu, Y.; Madsen, J.; Magnus, E.; Mahn, K. B. M.; Makino, Y.; Manao, E.; Mancina, S.; Mand, A.; Sainte, W. Marie; Mari?, I. C.; Marka, S.; Marka, Z.; Marsee, M.; Martinez-Soler, I.; Maruyama, R.; Mayhew, F.; McNally, F.; Mead, J. V.; Meagher, K.; Mechbal, S.; Medina, A.; Meier, M.; Merckx, Y.; Merten, L.; Mitchell, J.; Montaruli, T.; Moore, R. W.; Morii, Y.; Morse, R.; Moulai, M.; Mukherjee, T.; Naab, R.; Nakos, M.; Naumann, U.; Necker, J.; Negi, A.; Neste, L.; Neumann, M.; Niederhausen, H.; Nisa, M. U.; Noda, K.; Noell, A.; Novikov, A.; Pollmann, A. Obertacke; O'Dell, V.; Olivas, A.; Orsoe, R.; Osborn, J.; O'Sullivan, E.; Palusova, V.; Pandya, H.; Park, N.; Parker, G. K.; Parrish, V.; Paudel, E. N.; Paul, L.; Heros, C. Pérez de los; Pernice, T.; Peterson, J.; Pizzuto, A.; Plum, M.; Pontén, A.; Popovych, Y.; Rodriguez, M. Prado; Pries, B.; Procter-Murphy, R.; Przybylski, G. T.; Pyras, L.; Raab, C.; Rack-Helleis, J.; Rad, N.; Ravn, M.; Rawlins, K.; Rechav, Z.; Rehman, A.; Resconi, E.; Reusch, S.; Rhode, W.; Riedel, B.; Rifaie, A.; Roberts, E. J.; Robertson, S.; Rodan, S.; Rongen, M.; Rosted, A.; Rott, C.; Ruhe, T.; Ruohan, L.; Safa, I.; Saffer, J.; Salazar-Gallegos, D.; Sampathkumar, P.; Sandrock, A.; Santander, M.; Sarkar, S.; Sarkar, S.; Savelberg, J.; Savina, P.; Schaile, P.; Schaufel, M.; Schieler, H.; Schindler, S.; Schlickmann, L.; Schlüter, B.; Schlüter, F.; Schmeisser, N.; Schmidt, T.; Schneider, J.; Schröder, F. G.; Schumacher, L.; Schwirn, S.; Sclafani, S.; Seckel, D.; Seen, L.; Seikh, M.; Seo, M.; Seunarine, S.; Myhr, P. A. Sevle; Shah, R.; Shefali, S.; Shimizu, N.; Silva, M.; Skrzypek, B.; Smithers, B.; Snihur, R.; Soedingrekso, J.; Søgaard, A.; Soldin, D.; Soldin, P.; Sommani, G.; Spannfellner, C.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stürwald, T.; Stuttard, T.; Sullivan, G. W.; Taboada, I.; Ter-Antonyan, S.; Terliuk, A.; Thiesmeyer, M.; Thompson, W. G.; Thwaites, J.; Tilav, S.; Tollefson, K.; Tönnis, C.; Toscano, S.; Tosi, D.; Trettin, A.; Elorrieta, M. A. Unland; Upadhyay, A. K.; Upshaw, K.; Vaidyanathan, A.; Valtonen-Mattila, N.; Vandenbroucke, J.; Eijndhoven, N. van; Vannerom, D.; Santen, J. van; Vara, J.; Varsi, F.; Veitch-Michaelis, J.; Venugopal, M.; Vereecken, M.; Carrasco, S. Vergara; Verpoest, S.; Veske, D.; Vijai, A.; Walck, C.; Wang, A.; Weaver, C.; Weigel, P.; Weindl, A.; Weldert, J.; Wen, A. Y.; Wendt, C.; Werthebach, J.; Weyrauch, M.; Whitehorn, N.; Wiebusch, C. H.; Williams, D. R.; Witthaus, L.; Wolf, M.; Wrede, G.; Xu, X. W.; Yanez, J. P.; Yildizci, E.; Yoshida, S.; Young, R.; Yu, F.; Yu, S.; Yuan, T.; Zegarelli, A.; Zhang, S.; Zhang, Z.; Zhelnin, P.; Zilberman, P.; Zimmerman, M.; Drake, Pablo; Spira-Savett, Elizabeth; Lusen, Piatra; Mori, Kaya
While the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods used towards understanding this is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between May 20, 2022 and November 10, 2022. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is well described using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, and given the significance of the neutrino excess is at 3σ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation.
COSP-RTTOV-1.0: Flexible radiation diagnostics to enable new science applications in model evaluation, climate change detection, and satellite mission design
(45692) Shaw, Jonah K.; Swales, Dustin J.; Desouza-Machado, Sergio; Turner, David D.; Kay, Jennifer E.; Schneider, David P.
Infrared spectral radiation fields observed by satellites make up an information-rich, multi-decade record with continuous coverage of the entire planet. As direct observations, spectral radiation fields are also largely free from uncertainties that accumulate during geophysical retrieval and data assimilation processes. Comparing these direct observations with earth system models (ESMs), however, is hindered by definitional differences between the radiation fields satellites observe and those generated by models. Here, we present a flexible, computationally efficient tool called COSP-RTTOV for simulating satellitelike radiation fields within ESMs. Outputs from COSP-RTTOV are consistent with instrument spectral response functions and orbit sampling, as well as the physics of the host model. After validating COSP-RTTOV's performance, we demonstrate new constraints on model performance enabled by COSP-RTTOV. We show additional applications in climate change detection using the NASA AIRS instrument, and observing system simulation experiments using the NASA PREFIRE mission. In summary, COSP-RTTOV is a convenient tool for directly comparing satellite radiation observations with ESMs. It enables a wide range of scientific applications, especially when users desire to avoid the assumptions and uncertainties inherent in satellite-based retrievals of geophysical variables or in atmospheric reanalysis.
BatAnalysis -- A Comprehensive Python Pipeline for Swift BAT Time-Tagged Event Data Analysis
(2025-02-01) Parsotan, Tyler; Palmer, David M.; Ronchini, Samuele; Delaunay, James; Tohuvavohu, Aaron; Laha, Sibasish; Lien, Amy; Cenko, S. Bradley; Krimm, Hans; Markwardt, Craig
The Swift Burst Alert Telescope (BAT) is a coded aperture gamma-ray instrument with a large field of view that was designed to detect and localize transient events. When a transient is detected, either on-board or externally, the BAT saves time-tagged event (TTE) data which provides the highest quality information of the locations of the photons on the detector plane and their energies. This data can be used to produce spectra, lightcurves, and sky images of a transient event. While these data products are produced by the Swift Data Center and can be produced by current software, they are often preset to certain time and energy intervals which has limited their use in the current time domain and multi-messenger environment. Here, we introduce a new capability for the BatAnalysis python package to download and process TTE data under an open-source pythonic framework that allows for easy interfacing with other python packages. The new capabilities of the BatAnalysis software allows for TTE data to be used by the community in a variety of advanced customized analyses of astrophysical sources which BAT may have TTE data for, such as Fast Radio Bursts (FRBs), Gamma-ray Bursts (GRBs), Low Mass X-ray Binaries (LMXB), Soft Gamma-ray Repeaters, magnetars, and many other sources. We highlight the usefulness of the BatAnalysis package in analyzing TTE data produced by an on-board GRB trigger, a FRB external trigger, a sub-threshold detection of the LMXB EXO 0748-676, and an external trigger of a GRB that BAT detected during a slew.
A recoiling supermassive black hole in a powerful quasar
(2025-01-30) Chiaberge, Marco; Morishita, Takahiro; Boschini, Matteo; Bianchi, Stefano; Capetti, Alessandro; Castignani, Gianluca; Gerosa, Davide; Konishi, Masahiro; Koyama, Shuhei; Kushibiki, Kosuke; Lambrides, Erini; Meyer, Eileen T.; Motohara, Kentaro; Stiavelli, Massimo; Takahashi, Hidenori; Tremblay, Grant R.; Norman, Colin
Supermassive black holes (SMBH) are thought to grow through accretion of matter and mergers. Models of SMBH mergers have long suffered the final parsec problem, where SMBH binaries may stall before energy loss from gravitational waves (GW) becomes significant, leaving the pair unmerged. Direct evidence of coalesced SMBH remains elusive. Theory predicts that GW recoiling black holes can occur following a black hole merger. Here we present decisive spectroscopic evidence that the gas bound to the SMBH in the spatially offset quasar 3C 186 is blue-shifted relative to the host galaxy. This is exclusively explained by the GW recoil super-kick scenario. This confirmation of the ejection process implies that the final parsec problem is resolved in nature, providing evidence that even the most massive black holes can merge.
Towards enhanced precision in thermometry with nonlinear qubits
(IOP, 2025-01-29) Deffner, Sebastian
Quantum thermometry refers to the study of measuring ultra-low temperatures in quantum systems. The precision of such a quantum thermometer is limited by the degree to which temperature can be estimated by quantum measurements. More precisely, the maximal precision is given by the inverse of the quantum Fisher information. In the present analysis, we show that quantum thermometers that are described by nonlinear Schrödinger equations allow for a significantly enhanced precision, that means larger quantum Fisher information. This is demonstrated for a variety of pedagogical scenarios consisting of single and two-qubits systems. The enhancement in precision is indicated by non-vanishing quantum speed limits, which originate in the fact that the thermal, Gibbs state is typically not invariant under the nonlinear equations of motion.
The S-PLUS 12-band photometry as a powerful tool for discovery and classification: ten cataclysmic variables in a proof-of-concept study
(2025-01-27) Oliveira, Raimundo Lopes de; Araujo, Amanda S. de; Krabbe, Angela C.; Oliveira, Claudia L. Mendes de; Mukai, Koji; Gutierrez-Soto, Luis A.; Kanaan, Antonio; Eleuterio, Romualdo; Fernandes, Marcelo Borges; Quispe-Huaynasi, Fredi; Schoenell, William; Ribeiro, Tiago
Multi-band photometric surveys provide a straightforward way to discover and classify astrophysical objects systematically, enabling the study of a large number of targets at relatively low cost. Here we introduce an alternative approach to select Accreting White Dwarf (AWD) candidates following their spectral energy distribution, entirely supported by the twelve photometric bands of the Southern Photometric Local Universe Survey (S-PLUS). The method was validated with optical spectroscopic follow-up with the Gemini South telescope which unambiguously established ten systems as cataclysmic variables (CVs), alongside Swift X-ray observations of four of them. Among the ten CVs presented here are those that may be low-luminosity intermediate polars or WZ Sge-type dwarf novae with rare outbursts, two subclasses that can be easily missed in time-domain and X-ray surveys, the two methods currently dominating the discovery of new CVs. Our approach based on S-PLUS provides an important, complementary tool to uncover the total population of CVs and the complete set of its subclasses, which is an important step towards a full understanding of close binary evolution, including the origin of magnetic fields in white dwarfs and the physics of accretion. Finally, we highlight the potential of S-PLUS beyond AWDs, serving other surveys in the characterization of their sources.
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.

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