UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)

Permanent URI for this collectionhttp://hdl.handle.net/11603/7798

The Center for Space Sciences and Technology (CSST) is the administrative unit for UMBC’s participation in the CRESST consortium. The NASA Goddard Space Flight Center (NASA/GSFC), The University of Maryland College Park (UMCP), Catholic University, Howard University and Southeastern Universities Research Association (SURA) are our partners in the consortium.

The Center for Research and Exploration in Space Science & Technology (CRESST), is a cooperative agreement between the partner institutions. The CRESST consortium currently has over 120 PhD astronomers and astrophysicists working within the Astrophysics Science Division at GSFC.

CSST was formed in 2006 and currently has over 20 UMBC research faculty, several of which are affiliated to the physics department. The research conducted by the members of CSST focuses on (i) Astrophysical Data Reduction, Interpretation & Archiving, (ii) Space Science Technology: Development & Calibration, and (iii) Theoretical Astrophysics: Simulations & Software.

CSST maintains close relations with (and is housed within) the Physics Department at UMBC. Combined, UMBC astrophysics faculty and CSST scientists contribute to the Undergraduate & Graduate activities (including the Undergrad & Grad internships) by teaching & mentoring students.

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Development and Initial Testing of XR-Based Fence Diagrams for Polar Science
(IEEE, 2023-07) Tack, Naomi; Holschuh, Nicholas; Sharma, Sharad; Williams, Rebecca M.; Engel, Don
Earth’s ice sheets are the largest contributor to sea level rise. For this reason, understanding the flow and topology of ice sheets is crucial for the development of accurate models and predictions. In order to aid in the generation of such models, ice penetrating radar is used to collect images of the ice sheet through both airborne and ground-based platforms. Glaciologists then take these images and visualize them in 3D fence diagrams on a flat 2D screen. We aim to consider the benefits that an XR visualization of these diagrams may provide to enable better data comprehension, annotation, and collaborative work. In this paper, we discuss our initial development and evaluation of such an XR system.
Visualizing the Greenland Ice Sheet in VR using Immersive Fence Diagrams
(ACM, 2023-09-10) Tack, Naomi; Williams, Rebecca M.; Holschuh, Nicholas; Sharma, Sharad; Engel, Don
The melting of the ice sheets covering Greenland and Antarctica are primary drivers of sea level rise. Predicting the rate of ice loss depends on modeling the ice dynamics. Ice penetrating radar provides the ability to capture images through the ice sheet, down to the bedrock. Historical environmental and climate perturbations cause small changes to the dielectric constant of ice, which are visually manifested as layers of varying brightness in the radar imagery. To understand how the flow of ice has progressed between neighboring image slices, glaciologists use Fence Diagrams to visualize several cross-sections at once. Here, we describe the immersive virtual reality (VR) fence diagrams we have developed. The goal of our system is to enable glaciologists to make sense of these data and thereby predict future ice loss.
The timing and spectral properties of the 2022 outburst of SGR J1935+2154 observed with NICER
(APJ, 2025-01-13) Yu-Cong, Fu; Lin, Lin; Ming-Yu, Ge; Teruaki, Enoto; Chin-Ping, Hu; George, Younes; Ersin, Göğüş; Christian, Malacaria
The magnetar SGR J1935+2154 entered a new active episode on October 10, 2022, with X-ray bursts and enhanced persistent emission. At the tail of high burst rate interval, lasting several hours, radio bursts were detected, revealing the connection between the X-ray activities and radio emissions. We analyzed observations of SGR J1935+2154 for nearly three months, using data from Neutron Star Interior Composition Explorer (NICER). We report the timing and spectral results following the onset of this outburst. In general, the X-ray flux of the persistent emission decays exponentially. While a flare is evident on the light curve, a fast radio burst (FRB) was detected immediately following the peak of this flare. We found a phase jump of pulse profile, with a deviation of $0.16\pm0.03$ phase, which is related to the glitch. The spectra are well fit with the combination of a blackbody and a power law model. The decay of the outburst is dominated by the drop of the non-thermal component, which also leads to the increase of thermal proportion. The photon index of the power law is inversely correlated with both the unabsorbed flux and the burst rate. We find that unlike the large variety of the persistent emission around FRB 221014, the X-ray properties are very stable when FRBs 221021 and 221201 happened. These results manifest the connection between glitch, phase jump, X-ray burst, and radio burst, crucial for studying the mutation in twisted magnetic fields and constraining the trigger mechanism of radio bursts.
High-Frequency Power Spectrum of AGN NGC 4051 Revealed by NICER
(2025-01-22) Rani, Bindu; Kim, Jungeun; Papadakis, I.; Gendreau, K. C.; Masterson, M.; Hamaguchi, K.; Kara, E.; Lee, S.-S.; Mushotzky, R.
Variability studies offer a compelling glimpse into black hole dynamics, and NICER's (Neutron Star Interior Composition Explorer) remarkable temporal resolution propels us even further. NICER observations of an Active Galactic Nucleus (AGN), NGC 4051, have charted the geometry of the emission region of the central supermassive black hole. Our investigation of X-ray variability in NGC 4051 has detected extreme variations spanning a factor of 40 to 50 over a mere 10 to 12 hours. For the first time, we have constrained the X-ray Power Spectral Density (PSD) of the source to 0.1 Hz, corresponding to a temporal frequency of 10,000 Hz in a galactic X-ray binary (GXRB) with a mass of 10 M_{\odot}. No extra high-frequency break/bend or any quasi-periodic oscillations are found. Through detailed analysis of energy-dependent PSDs, we found that the PSD normalization, the high-frequency PSD slope as well as the bending frequency remains consistent across all energies within the 0.3-3 keV band, revealing the presence of a constant temperature corona. These significant findings impose critical constraints on current models of X-ray emission and variability in AGN.
Performance of the 0-padding Optimal Filter Method in Non-linear Gain Calibration
(IEEE, 2025-01-22) Witthoeft, Michael; Smith, Stephen J.; Cucchettic, Edoardo; Cardiel, Nicolas; Ceballosf, M. Teresa; Cobo, Beatriz; Adams, Joseph S.; Bandler, Simon R.; Chervenak, James A.; Finkbeiner, Fred M.; Fuhrman, Joshua; Hull, Samuel V.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, F. Scott; Sakai, Kazuhiro; Wakeham, Nicholas
The focal-plane detector, the X-ray Integral Field Unit (X-IFU), on-board ESA's Athena space telescope is a transition edge sensor (TES) microcalorimeter array with 1.5k pixels, designed to provide spatially-resolved, high-resolution spectroscopy over the energy range 0.2-12 keV. The onboard event processor uses a digital optimal filter to determine the pulse-height of the measured current pulse from every X-ray photon striking the array. A modified optimal filter called the 0-padding filter has recently been proposed. This is a truncated version of the standard optimal filter and has been shown to provide comparable energy resolution but with the benefit of reduced computational expense. Whereas the standard optimal filter has zero integral and is not sensitive to variations in the DC level of the measured signal, the integral of the 0-padded version is non-zero and thus is more sensitive to fluctuations in DC signal over time. In this work, we explore the effect of 0-padding on the energy scale calibration using data from 250-pixels in a prototype Athena X-IFU array, measured over the range 1.3-12 keV.
AstroPix: A Pixelated HVCMOS Sensor for Space-Based Gamma-Ray Measurement
(2025-01-20) Steinhebel, Amanda L.; Caputo, Regina; Violette, Daniel P.; Affolder, Anthony; Bauman, Autumn; Chinatti, Carolyn; Deshmukh, Aware; Fadayev, Vitaliy; Fukazawa, Yasushi; Jadhav, Manoj; Kierans, Carolyn; Kim, Bobae; Kim, Jihee; Klest, Henry; Kroger, Olivia; Kumar, Kavic; Kushima, Shin; Lauenstein, Jean-Marie; Leys, Richard; Martinez-Mckinney, Forest; Metcalfe, Jessica; Metzler, Zachary; Mitchell, John W.; Nakano, Norito; Ott, Jennifer; Peric, Ivan; Perkins, Jeremy S.; Rudin, Max R.; Taylor; Shin; Sommer, Grant; Striebig, Nicolas; Suda, Yusuke; Tajima, Hiroyasu; Valverde, Janeth; Zurek, Maria
A next-generation medium-energy gamma-ray telescope targeting the MeV range would address open questions in astrophysics regarding how extreme conditions accelerate cosmic-ray particles, produce relativistic jet outflows, and more. One concept, AMEGO-X, relies upon the mission-enabling CMOS Monolithic Active Pixel Sensor silicon chip AstroPix. AstroPix is designed for space-based use, featuring low noise, low power consumption, and high scalability. Desired performance of the device include an energy resolution of 5 keV (or 10% FWHM) at 122 keV and a dynamic range per-pixel of 25-700 keV, enabled by the addition of a high-voltage bias to each pixel which supports a depletion depth of 500 um. This work reports on the status of the AstroPix development process with emphasis on the current version under test, version three (v3), and highlights of version two (v2). Version 3 achieves energy resolution of 10.4 +\- 3.2 % at 59.5 keV and 94 +\- 6 um depletion in a low-resistivity test silicon substrate.
Mapping Venus’s Gravity Field with the VERITAS Mission
(AAS, 2025-01-16) Giuliani, Flavia; Durante, Daniele; Cascioli, Gael; Marchi, Fabrizio De; Iess, Luciano; Mazarico, Erwan; Smrekar, Suzanne
The Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy (VERITAS) mission, selected by the NASA Discovery program in 2021, addresses crucial scientific questions about Venus’s evolution, structure, and past and ongoing geological processes. The high-resolution mapping of the gravity field of the planet will give an essential contribution to meet the science objectives of the mission and to further our understanding of Venus. The VERITAS gravity science experiment will enable a gravity map of the planet with substantially higher and more uniform spatial resolution with respect to Magellan. This is achieved thanks to the near-polar, near-circular, lowaltitude orbit (~220 km), and the state-of-the-art quality of Doppler tracking data, collected from two separate and coherent radio links at X and Ka band. Our numerical simulations show that the VERITAS gravity science experiment can robustly fulfill the scientific requirements, achieving a gravity field spatial resolution ranging from 85 to 120 km. Across 90% of the planet, a spatial resolution better than 106 km is expected. Additionally, VERITAS can retrieve crucial parameters required to derive the tidal response and rotational state of Venus, thereby improving our understanding of the planet’s interior structure.
Non-stop Variability of Sgr A* using JWST at 2.1 and 4.8 micron Wavelengths: Evidence for Distinct Populations of Faint and Bright Variable Emission
(2025-01-07) Yusef-Zadeh, F.; Bushouse, H.; Arendt, Richard; Wardle, M.; Michail, J. M.; Chandler, C. J.
We present first results of JWST Cycle 1 and 2 observations of Sgr A* using NIRCam taken simultaneously at 2.1 and 4.8 micron for a total of ~48 hours over seven different epochs in 2023 and 2024. We find correlated variability at 2.1 and 4.8 micron in all epochs, continual short-time scale (a few seconds) variability and epoch-to-epoch variable emission implying long-term ( ~days to months) variability of Sgr A*. A highlight of this analysis is the evidence for sub-minute, horizon-scale time variability of Sgr A*, probing inner accretion disk size scales. The power spectra of the light curves in each observing epoch also indicate long-term variable emission. With continuous observations, JWST data suggest that the flux of Sgr A* is fluctuating constantly. The flux density correlation exhibits a distinct break in the slope at ~3 mJy at 2.1 micron. The analysis indicates two different processes contributing to the variability of Sgr A*. Brighter emission trends towards shallower spectral indices than the fainter emission. Cross correlation of the light curves indicates for the first time, a time delay of 3 - 40 sec in the 4.8 micron variability with respect to 2.1 micron. This phase shift leads to loops in plots of flux density vs spectral index as the emission rises and falls. Modeling suggests that the synchrotron emission from the evolving, age-stratified electron population reproduces the shape of the observed light curves with a direct estimate of the magnetic field strengths in the range between 40-90 G, and upper cutoff energy, E_c, between 420 and 720 MeV.
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.
OpenUniverse2024: A shared, simulated view of the sky for the next generation of cosmological surveys
(2025-01-10) OpenUniverse; The LSST Dark Energy Science Collaboration; The Roman HLIS Project Infrastructure Team; The Roman RAPID Project Infrastructure Team Team; The Roman Supernova Cosmology Project Infrastructure Team; Alarcon, A.; Aldoroty, L.; Beltz-Mohrmann, G.; Bera, A.; Blazek, J.; Bogart, J.; Braeunlich, G.; Broughton, A.; Cao, K.; Chiang, J.; Chisari, N. E.; Desai, V.; Fang, Y.; Galbany, L.; Hearin, A.; Heitmann, K.; Hirata, C.; Hounsell, Rebekah; Jain, B.; Jarvis, M.; Jencson, J.; Kannawadi, A.; Kasliwal, M. K.; Kessler, R.; Kiessling, A.; Knop, R.; Kovacs, E.; Laher, R.; Laliotis, K.; Lin, C.; Lopes, I.; Mahabal, A.; Mandelbaum, R.; Masiero, J.; Mau, S.; Meehan, C.; Meyers, J.; Moraes, B.; Paladini, R.; Pearl, A.; Malagon, A. Plazas; Rose, B.; Rubin, D.; Rusholme, B.; Santos, A.; 奱r?evi?, N.; Scolnic, D.; Troxel, M. A.; Alfen, N. Van; Dyke, S. Van; Walter, C. W.; Wu, T.; Yamamoto, M.; Yan, Y.; Zhang, T.
The OpenUniverse2024 simulation suite is a cross-collaboration effort to produce matched simulated imaging for multiple surveys as they would observe a common simulated sky. Both the simulated data and associated tools used to produce it are intended to uniquely enable a wide range of studies to maximize the science potential of the next generation of cosmological surveys. We have produced simulated imaging for approximately 70 deg² of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Wide-Fast-Deep survey and the Nancy Grace Roman Space Telescope High-Latitude Wide-Area Survey, as well as overlapping versions of the ELAIS-S1 Deep-Drilling Field for LSST and the High-Latitude Time-Domain Survey for Roman. OpenUniverse2024 includes i) an early version of the updated extragalactic model called Diffsky, which substantially improves the realism of optical and infrared photometry of objects, compared to previous versions of these models; ii) updated transient models that extend through the wavelength range probed by Roman and Rubin; and iii) improved survey, telescope, and instrument realism based on up-to-date survey plans and known properties of the instruments. It is built on a new and updated suite of simulation tools that improves the ease of consistently simulating multiple observatories viewing the same sky. The approximately 400 TB of synthetic survey imaging and simulated universe catalogs are publicly available, and we preview some scientific uses of the simulations.
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.
X-ray polarization of the magnetar 1E 1841-045 in outburst
(2024-12-20) Stewart, Rachael; Younes, George; Harding, Alice; Wadiasingh, Zorawar; Baring, Matthew; Negro, Michela; Strohmayer, Tod; Ho, Wynn; Ng, Mason; Arzoumanian, Zaven; Thi, Hoa Dinh; Lalla, Niccolo' Di; Enoto, Teruaki; Gendreau, Keith; Hu, Chin-Ping; Kooten, Alex van; Kouveliotou, Chryssa; McEwen, Alexander
We report on IXPE and NuSTAR observations that began forty days following the onset of the 2024 outburst of the magnetar 1E 1841-045, marking the first ever IXPE observation of a magnetar in an enhanced state. Our spectropolarimetric analysis indicates that a non-thermal double power-law (PL) spectral model can fit the phase-averaged intensity data well, with the soft and hard components dominating below and above around 5 keV, respectively. We find that the soft PL exhibits a polarization degree (PD) of about 20% while the hard X-ray PL displays a PD of about 50%; both components have a polarization angle (PA) compatible with 0 degree. These results are supported through model-independent polarization analysis which shows an increasing PD from about 15% to 70% in the 2-3 keV and 6-8 keV ranges, respectively, while the PA remains consistent with 0 degree. We find marginal evidence for variability in the polarization properties with pulse phase, namely a higher PD at spin phases coinciding with the peak in the hard X-ray pulse. We compare the hard X-ray PL to the expectation from direct resonant inverse Compton scattering (RICS) and secondary pair cascade synchrotron radiation from primary high-energy RICS photons, finding that both can provide reasonable spectropolarimetric agreement with the data, yet, the latter more naturally. Finally, we suggest that the soft power law X-ray component may be emission emanating from a Comptonized corona in the inner magnetosphere.
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.
Infrared Band Strengths and Other Properties of Three Interstellar Compounds—Amorphous Isocyanic Acid, Formaldehyde, and Formic Acid
(IOP Science, 2024-12-09) Hudson, Reggie L.; Yarnall, Yukiko; Gerakines, Perry A.
Infrared (IR) spectral features of interstellar and solar system ices have been attributed to solid organic and inorganic compounds for over 50 yr, but in many cases the laboratory IR data needed to fully quantify such work have never been published, forcing researchers to rely on assumptions about gas- or liquid-phase measurements to interpret data for ices. Here, we report the first mid-IR intensity measurements for isocyanic acid (HNCO) ices that are free of such assumptions, providing new results for use by both observational and laboratory astrochemists. We also report similar new IR data for both formaldehyde (H₂CO) and formic acid (HCOOH), which have been discussed in the astrochemical literature for decades, but again without adequate laboratory data to help quantify observational results. Densities and refractive indices of HNCO, H₂CO, and HCOOH as amorphous ices also are reported. Two applications of the new H₂CO work are presented, the first vapor-pressure measurements of solid H₂CO, along with an enthalpy of sublimation, at 100 to 109 K and a set of IR intensities of H₂CO in H₂O + H₂CO ices. Band strengths, absorption coefficients, and optical constants are calculated for all three compounds. Extensive comparisons are made to older results, which are not recommended for future use.
Influence of Bulk Compressibility on Tides in Rocky and Icy Worlds
(2024-12-12) Renaud, Joe P.; Wagner, Nick; Cascioli, Gael; Goossens, Sander J.; Henning, Wade
The tidal response of terrestrial planets or icy moons is a complex interplay between the interior and orbit of the world. A significant factor in this response comes from the thermal and viscoelastic state of the deep interior. Suggesting that if measurements of the tidal and mass-loading (if applicable) response are obtained with sufficient precision, then tides can provide a probe of these properties that are otherwise hidden from other measurement techniques. This has been utilized across the Solar System to constrain questions such as, does Mercury or Venus have a solid core? Does our Moon have significant partial melting in its mantle? Or do icy moons in the outer Solar System contain large, and astrobiologically relevant, liquid oceans? New missions like BepiColombo, VERITAS, Europa Clipper, and more will provide high-precision measurements of tidally-relevant properties such as the Love Number k₂ (and perhaps h₂ and their phase lags). However, linking these observations to the interior requires proper modeling of all the major factors that drive changes in these values.In this study, we look at an often-omitted concept in tidal modeling: Bulk Compressibility, which is the inclusion of bulk modulus in the viscoelastic-gravitational equations used to calculate planetary Love numbers. Including bulk modulus can be mathematically and computationally complex so it is not uncommon to ignore it. This is occasionally justified by the misnomer of “compressibility” being only relevant to large bodies. However, bulk compressibility is not directly dependent on the size or mass of a planet. Instead, it provides another degree of freedom for the world to respond to tidal or loading stresses.In this presentation, we will discuss the background and theory behind bulk compressibility and showcase that its addition can have a measurable impact on tidal and loading Love numbers. For example, work by this team has shown that it can lead to >20% difference in the tidal and loading Love number k₂ and up to 40% difference for h₂. Furthermore, it can significantly alter the phase lag of these numbers which is an important probe of thermal and rheological properties. Finally, we will discuss when bulk compressibility can be ignored and what sort of measurement precision is most affected.
IN ISLANDIA, VERITAS: CHARACTERIZATION OF VENUS SURFACE ANALOGS
(USRA, 2024) Nunes, D. C.; Smrekar, S. E.; Hensley, S; Adeli, S.; Alemanno, G.; Cascioli, Gael; Zebker, H.
A RADIO SCIENCE EXPERIMENT TO STUDY THE INTERIOR OF THE URANIAN MOONS.
(Space Pole, 2024) Filice, Valerio; Cascioli, Gael; Le Maistre, Sebastien; Baland, Rose-Marie; Mazarico, Erwan; Goossens, Sander J.
The five largest moons of Uranus, as well as Uranus itself, have mostly been studied through ground-based observations [e.g., 1]. Only Voyager 2 provided in situ measurements that significantly enhanced our understanding of the system [2,3]. As a ten-year launch window approaches, the scientific community has agreed on the importance of prioritizing a robotic mission to Uranus, proposing it as the next NASA flagship-class mission [4]. In response to this, NASA is reviewing the Uranus Orbiter and Probe (UOP) mission concept [5]. The concept was evaluated by the most recent Planetary Science and Astrobiology Decadal Survey [4] as a low-risk, relatively low-cost, and high-reward mission. Upon arrival, the mission would deploy an atmospheric probe, settle into orbit around Uranus for 4.5 Earth years, and conduct flybys of several moons. A Radio Science (RS) experiment that includes multiple satellite flybys (in addition to the orbital phase around Uranus) can provide valuable information about the interior properties, formation, evolution, and potential habitability of the planetary bodies in the Uranian system, as previously demonstrated [6-7]. An RS experiment can answer key science questions regarding the internal structure and rock-to-ice ratios of the large satellites of Uranus, and help identifying significant internal heat sources or possible oceans.

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