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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Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations
(IOP, 2024-11-25) Abdollahi, S.; Baldini, L.; Barbiellini, G.; Bellazzini, R.; Berenji, B.; Bissaldi, E.; Blandford, R. D.; Bonino, R.; Bruel, P.; Buson, S.; Cameron, R. A.; Caraveo, P. A.; Casaburo, F.; Cavazzuti, E.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cozzolongo, G.; Orestano, P. Cristarella; Cutini, S.; D’Ammando, F.; Lalla, N. Di; Dirirsa, F.; Venere, L. Di; Domínguez, A.; Fegan, S. J.; Ferrara, E. C.; Fiori, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Garrappa, S.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Grenier, I. A.; Guiriec, S.; Hays, E.; Horan, D.; Kuss, M.; Larsson, S.; Laurenti, M.; Li, J.; Liodakis, I.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Marcotulli, L.; Martí-Devesa, G.; Mazziotta, M. N.; Mereu, I.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perri, M.; Persic, M.; Pesce-Rollins, M.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Rani, Bindu; Razzano, M.; Reimer, A.; Reimer, O.; Parkinson, P. M. Saz; Scotton, L.; Serini, D.; Sesana, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, M. N.; Tak, D.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Valverde, Janeth; Verrecchia, F.; Zaharijas, G.
A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ?7 yr of data from the Fermi Large Area Telescope. After 15 yr of Fermi sky-survey observations, doubling the total time range, we report >7 cycle gamma-ray modulation with an estimated significance of 4? against stochastic red noise. Independent determinations of oscillation period and phase in the earlier and the new data are in close agreement (chance probability <0.01). Pulse timing over the full light curve is also consistent with a coherent periodicity. Multiwavelength new data from Swift X-Ray Telescope, Burst Alert Telescope, and UVOT, and from KAIT, Catalina Sky Survey, All-Sky Automated Survey for Supernovae, and Owens Valley Radio Observatory ground-based observatories as well as archival Rossi X-Ray Timing Explorer satellite-All Sky Monitor data, published optical data of Tuorla, and optical historical Harvard plates data are included in our work. Optical and radio light curves show clear correlations with the gamma-ray modulation, possibly with a nonconstant time lag for the radio flux. We interpret the gamma-ray periodicity as possibly arising from a pulsational accretion flow in a sub-parsec binary supermassive black hole system of elevated mass ratio, with orbital modulation of the supplied material and energy in the jet. Other astrophysical scenarios introduced include instabilities, disk and jet precession, rotation or nutation, and perturbations by massive stars or intermediate-mass black holes in polar orbit.
Visualization for Cyber Complex Systems: Application, Issues and Future Work
(2024) Nikolov, Georgi; Varga, Margaret; Träber-Burdin, Susan; Winkelholz, Carsten; Kullman, Kaur; Lavigne, Valérie
Technology advances at a rapid pace; new components are being developed, offering opportunities to create even more intricate networks of devices, interconnected on both local and global scale, offering ever faster processing while generating vast amounts of data. Technological advancements facilitate improvements for individuals’ daily lives, our work environment, societal enhancements, military defense capabilities, etc. Unfortunately, when an issue manifests in these new networks, it is often difficult to immediately identify the origin and apply an appropriate solution in a timely fashion. The infrastructure built to sustain our society’s needs has become complicated and interconnected, evolving into a complex system rather than a complicated one. Complex systems are difficult to manage without an in-depth knowledge of the underlying components and their interactions - where the whole is greater than the sum of its parts. To aid in this task, new ways to visualize such a system of systems need to be developed to represent them accordingly and enable its operators to identify problems and apply actionable solutions. In this paper, we offer a detailed explanation on what complex systems are, the difficulty of maintaining actionable situational awareness and understanding, and how Visual Analytics and Data Visualization can help in resolving some of these issues. Examples of visual representations will be discussed, together with techniques used for their evaluations in terms of their usefulness and usability. Finally, a brief overview of possible future advancements that can support better understanding and management of complex systems will be discussed.
Understanding Titan’s Prebiotic Chemistry: Synthesizing Amino Acids Through Aminonitrile Alkaline Hydrolysis
(ACS, 2024-11-20) Farnsworth, Kendra; McLain, Hannah L.; Chung, Angela; Trainer, Melissa G.
Titan is an ocean world with a plethora of organic material in its atmosphere and on its surface, making it an intriguing location in the search for habitable environments beyond Earth. Settled aerosols will mix with transient surface melts following cryovolcanic eruptions and impact events, driving hydrolysis reactions and prebiotic chemistry. Previous studies have shown that the hydrolysis of laboratory-synthesized Titan organics leads to the production of amino acids and other prebiotic molecules. The exact molecular structure of Titan aerosols remains unclear, yet aminonitriles have been hypothesized to be among the organic components. This laboratory study tested three reaction pathways that could potentially lead to the formation of amino acids: aminoacetonitrile → glycine, 2-aminopropanenitrile → alanine, and 4-aminobutanenitrile → γ-aminobutyric acid. Liquid chromatography mass spectrometry (LCMS) is used to quantify the abundance of amino acids over a 6-month period. We conclude that ammonia plays a key role in the synthesis of amino acids from aminonitriles, while the inclusion of salts (1 wt %) and minerals (25 mg/mL) did not have a significant effect on amino acid formation compared to ammonia. Rate constants (k) for alkaline hydrolysis of the aminonitriles were calculated. Our results suggest that if Titan’s surface melts have a composition, including at least 5% ammonia in water, and if aminonitriles are present in Titan’s organic aerosols, then amino acids will likely form. These results are highly relevant to the Dragonfly mission to Titan, which will sample impact melt material at Selk crater to search for prebiotic molecules.
Dual Laser Indium Phosphide Photonic Integrated Circuits for Remote Active Carbon Dioxide Sensing
(Optica, 2022-03-06) Sang, Fengqiao; Rosborough, Victoria; Fridlander, Joseph; Gambini, Fabrizio; Brunelli, Simone Šuran; Chen, Jeffrey R.; Kawa, Stephan R.; Numata, Kenji; Stephen, Mark; Coldren, Larry; Klamkin, Jonathan
Two generations of indium phosphide photonic integrated circuits were fabricated, characterized, and their performance compared. Successful sampling of carbon dioxide was performed in a laboratory setting under continuous wave sampling.
A Novel 16-Channel WDM Silicon Photonics Transceiver with Interleavers for Simplified Ring Modulator/Filter Implementation
(Optica, 2022-05-15) Liu, Yuan; Gambini, Fabrizio; Pinna, Sergio; Meena, G. G.; Moreira, Renan; Preisler, Edward; Klamkin, Jonathan
We present a compact ring resonator based silicon photonics transceiver with 16-channel wavelength-division-multiplexing. 56 Gbps data transmission was achieved for a single ring modulator in depletion mode operation, which can support tera-bits-per-second capability for the transceiver.
High-Density and High-Efficiency Silicon Photonics Optical Interconnects for Space Division Multiplexing with Multi-Core Fiber
(Optica, 2022-05-15) Liu, Yuan; Gambini, Fabrizio; Meena, G. G.; Mcgivney, Michael; Moreira, Renan; Preisler, Edward; Klamkin, Jonathan
We present an architecture for space-division-multiplexing with multi-core-fiber (MCF) for high-density and high-efficiency short-reach optical interconnects. A silicon photonics transceiver with tera-bits-per-second capability and high-efficiency dual-layer grating couplers for MCF fan-in/fan-out are demonstrated.
The Hyperspectral Microwave Photonic Instrument (HyMPI) (poster)
(NTRS, 2024-04-04) Gambini, Fabrizio; Torres, V.; Robles, D.; Leong, E.; Mohammed, P.; Coon, M.; Banting, R.; Piepmeier, J.; Stephen, M.; Gambacorta, A.
The Hyperspectral Microwave Photonic Instrument (HyMPI)
(NTRS, 2024-05-22) Torres, Victor; Gambini, Fabrizio; Robles, David; Leong, Edward; Mohammed, Priscilla; Coon, Michael; Banting, Roger; Piepmeier, Jeffrey; Gambacorta, Antonia; Stephen, Mark
Photonic Integrated Circuits (PICs) in Space: The Hyperspectral Microwave Photonic Instrument (HyMPI)
(NTRS, 2024-06-05) Torres, Victor; Stephen, Mark; Gambini, Fabrizio; Mohammed, Priscilla; Blaisdell, John; Zhou, Yaping; Piepmeier, Jeffrey; Gambacorta, Antonia; Swap, Robert; Adams, Ian; Shahroudi, Narges; Rosenberg Robert; MacKinnon, James; Kotsakis, Alexander
Technology Progress on the Hyperspectral Microwave Photonic Instrument (HyMPI)
(NTRS, 2024-01-18) Gambini, Fabrizio; Torres, Victor; Robles, David; Leong, Edward; Racette, Paul; Mohammed, Priscilla; Sullivan, Dan; Coon, Michael; Banting, Roger; Piepmeier, Jeffrey; Gambacorta, Antonia; Stephen, Mark
The West-Coast Hyperspectral Microwave Sensor Intensive Experiment (WHyMSIE): A Prototype for A PBL Mission of Missions
(NTRS, 2024-05-20) Gambacorta, Antonia; Kotsakis, Alexander; Kroodsma, Rachael; MacKinnon, James; Zhou, Yaping; Shahroudi, Narges; Gong, Jie; Moradi, Isaac; Santanello, Joseph; Piepmeier, Jeff; Stephen, Mark; Gambini, Fabrizio; Mohammed, Priscilla; Fritts, Matt; McLinden, Matt; Adams, Ian; Platnick, Steve; Oreopoulos, Lazaros; Swap, Robert
We present an overview of the 2024 West-Coast Hyperspectral Microwave Sensor Intensive Experiment(WHyMSIE). WHyMSIE is a joint NASA-NOAA multi-sensor airborne experiment, embracing passive and active sensors from the Program of Record (PoR) along with novel technology funded through the NASA ESTO Instrument Incubation Program. At the core of this effort is the demonstration of the Conical Scanning Millimeter-wave Imaging Radiometer Hyperspectral (CoSMIR-H) instrument, a PBL DSI funded effort to develop hyperspectral sounding capability in the thermal microwave domain finalized to improved temperature and water vapor soundings in the Earth’s Planetary Boundary Layer (PBL). An overview of the field campaign design, instrument payload and validation plan is presented here.
Outer Solar System spacecraft without drag-free control to probe the μHz gravitational wave frontier
(2024-11-22) McQuinn, Matthew; McGrath, Casey
The microhertz frequency band of gravitational waves probes the merger of supermassive black holes as well as many other gravitational wave phenomena. However, space-interferometry methods that use test masses would require substantial development of test-mass isolation systems to detect anticipated astrophysical events. We propose an approach that avoids inertial test masses by situating spacecraft in the low-acceleration environment of the outer Solar System. We show that for Earth-spacecraft and inter-spacecraft distances of ≳10 AU, the accelerations on the spacecraft would be sufficiently small to potentially achieve sensitivities determined by stochastic gravitational wave backgrounds. We further argue, for arm lengths of 10−30 AU and 10 Watt transmissions, that stable phase locks should be achievable with 20 cm mirrors or 5 m radio dishes. We discuss designs that send both laser beams and radio waves between the spacecraft, finding that despite the ∼10 ⁴× longer wavelengths, even a design with radio transmissions could reach stochastic background-limited sensitivities at ≲0.3×10⁻⁴ Hz. Operating in the radio significantly reduces many spacecraft design tolerances. Our baseline concept requires two arms to do interferometry. However, if one spacecraft carries a clock with Allan deviations at 10 ⁴ seconds of 10⁻¹⁷, a comparable sensitivity could be achieved with a single arm. Finally, we discuss the feasibility of achieving similar gravitational wave sensitivities in a `Doppler tracking' configuration where the single arm is anchored to Earth.
Search for Extended GeV Sources in the Inner Galactic Plane
(2024-11-11) Abdollahi, S.; Acero, F.; Acharyya, A.; Adelfio, A.; Ajello, M.; Baldini, L.; Ballet, J.; Bartolini, C.; Gonzalez, J. Becerra; Bellazzini, R.; Bissaldi, E.; Bonino, R.; Bruel, P.; Cameron, R. A.; Caraveo, P. A.; Castro, D.; Cavazzuti, E.; Cheung, C. C.; Cibrario, N.; Ciprini, S.; Cozzolongo, G.; Orestano, P. Cristarella; Cuoco, A.; Cutini, S.; D'Ammando, F.; Lalla, N. Di; Dinesh, A.; Venere, L. Di; Domínguez, A.; Fiori, A.; Funk, S.; Fusco, P.; Gargano, F.; Gasbarra, C.; Gasparrini, D.; Germani, S.; Giacchino, F.; Giglietto, N.; Giliberti, M.; Giordano, F.; Giroletti, M.; Green, D.; Grenier, I. A.; Guillemot, L.; Guiriec, S.; Gupta, R.; Hashizume, M.; Hays, E.; Hewitt, J. W.; Horan, D.; Hou, X.; Kayanoki, T.; Kuss, M.; Laviron, A.; Lemoine-Goumard, M.; Liguori, A.; Li, J.; Liodakis, I.; Loizzo, P.; Longo, F.; Loparco, F.; Lorusso, L.; Lovellette, M. N.; Lubrano, P.; Maldera, S.; Malyshev, D.; Martí-Devesa, G.; Martin, P.; Mazziotta, M. N.; Mereu, I.; Michelson, P. F.; Mirabal, Nestor; Mitthumsiri, W.; Mizuno, T.; Monti-Guarnieri, P.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Omodei, N.; Orienti, M.; Orlando, E.; Paneque, D.; Panzarini, G.; Persic, M.; Pesce-Rollins, M.; Pillera, R.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Bernal, M. Rocamora; Sánchez-Conde, M.; Parkinson, P. M. Saz; Serini, D.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Tajima, H.; Thayer, J. B.; Torres, D. F.; Valverde, Janeth; Wadiasingh, Z.; Wood, K.; Zaharijas, G.
The recent detection of extended γ-ray emission around middle-aged pulsars is interpreted as inverse-Compton scattering of ambient photons by electron-positron pairs escaping the pulsar wind nebula, which are confined near the system by unclear mechanisms. This emerging population of γ-ray sources was first discovered at TeV energies and remains underexplored in the GeV range. To address this, we conducted a systematic search for extended sources along the Galactic plane using 14 years of Fermi-LAT data above 10 GeV, aiming to identify a number of pulsar halo candidates and extend our view to lower energies. The search covered the inner Galactic plane (|l|≤ 100∘, |b|≤ 1∘) and the positions of known TeV sources and bright pulsars, yielding broader astrophysical interest. We found 40 such sources, forming the Second Fermi Galactic Extended Sources Catalog (2FGES), most with 68% containment radii smaller than 1.0∘ and relatively hard spectra with photon indices below 2.5. We assessed detection robustness using field-specific alternative interstellar emission models and by inspecting significance maps. Noting 13 sources previously known as extended in the 4FGL-DR3 catalog and five dubious sources from complex regions, we report 22 newly detected extended sources above 10 GeV. Of these, 13 coincide with H.E.S.S., HAWC, or LHAASO sources; six coincide with bright pulsars (including four also coincident with TeV sources); six are associated with 4FGL point sources only; and one has no association in the scanned catalogs. Notably, six to eight sources may be related to pulsars as classical pulsar wind nebulae or pulsar halos.
Panning for gold with the Neil Gehrels Swift Observatory: an optimal strategy for finding the counterparts to gravitational wave events
(2024-11-07) Eyles-Ferris, R. A. J.; Evans, P. A.; Breeveld, A. A.; Cenko, S. B.; Dichiara, S.; Kennea, J. A.; Klingler, Noel; Kuin, N. P. M.; Marshall, F. E.; Oates, S. R.; Page, M. J.; Ronchini, S.; Siegel, M. H.; Tohuvavohu, A.; Campana, S.; D'Elia, V.; Osborne, J. P.; Page, K. L.; Pasquale, M. De; Troja, E.
The LIGO, Virgo and KAGRA gravitational wave observatories are currently undertaking their O4 observing run offering the opportunity to discover new electromagnetic counterparts to gravitational wave events. We examine the capability of the Neil Gehrels Swift Observatory (Swift) to respond to these triggers, primarily binary neutron star mergers, with both the UV/Optical Telescope (UVOT) and the X-ray Telescope (XRT). We simulate Swift's response to a trigger under different strategies using model skymaps, convolving these with the 2MPZ catalogue to produce an ordered list of observing fields, deriving the time taken for Swift to reach the correct field and simulating the instrumental responses to modelled kilonovae and short gamma-ray burst afterglows. We find that UVOT using the u filter with an exposure time of order 120 s is optimal for most follow-up observations and that we are likely to detect counterparts in ∼6% of all binary neutron star triggers. We find that the gravitational wave 90% error area and measured distance to the trigger allow us to select optimal triggers to follow-up. Focussing on sources less than 300 Mpc away or 500 Mpc if the error area is less than a few hundred square degrees, distances greater than previously assumed, offer the best opportunity for discovery by Swift with ∼5−30% of triggers having detection probabilities ≥0.5. At even greater distances, we can further optimise our follow-up by adopting a longer 250 s or 500 s exposure time.
Characterization of a peculiar Einstein Probe transient EP240408a: an exotic gamma-ray burst or an abnormal jetted tidal disruption event?
(2024-10-29) O'Connor, B.; Pasham, D.; Andreoni, I.; Hare, J.; Beniamini, P.; Troja, E.; Ricci, R.; Dobie, D.; Chakraborty, J.; Ng, M.; Klingler, N.; Karambelkar, V.; Rose, S.; Schulze, S.; Ryan, G.; Dichiara, S.; Monageng, I.; Buckley, D.; Hu, L.; Srinivasaragavan, G.; Bruni, G.; Cabrera, T.; Cenko, S. B.; Eerten, H. van; Freeburn, J.; Hammerstein, E.; Kasliwal, M.; Kouveliotou, C.; Kunnumkai, K.; Leung, J. K.; Lien, Amy; Palmese, A.; Sakamoto, T.
We present the results of our multi-wavelength (X-ray to radio) follow-up campaign of the Einstein Probe transient EP240408a. The initial 10 s trigger displayed bright soft X-ray (0.5-4 keV) radiation with peak luminosity Lₓ≳10⁴⁹ (10⁵⁰) erg s⁻¹ for an assumed redshift z>0.5 (2.0). The Neil Gehrels Swift Observatory and Neutron star Interior Composition ExploreR discovered a fading X-ray counterpart lasting for ∼5 d (observer frame), which showed a long-lived (~4 d) plateau-like emission (t⁻⁰.⁵) before a sharp powerlaw decline (t⁻⁷). The plateau emission was in excess of Lₓ≳10⁴⁶ (10⁴⁷) erg s⁻¹ at z>0.5 (2.0). Deep optical and radio observations resulted in non-detections of the transient. Our observations with Gemini South revealed a faint potential host galaxy (r≈24 AB mag) near the edge of the X-ray localization. The faint candidate host, and lack of other potential hosts (r≳26 AB mag; J≳23 AB mag), implies a higher redshift origin (z>0.5), which produces extreme X-ray properties that are inconsistent with many known extragalactic transient classes. In particular, the lack of a bright gamma-ray counterpart, with the isotropic-equivalent energy (10−10,000 keV) constrained by GECam and Konus-Wind to Eγ,iso≲4×10⁵¹ (6×10⁵²) erg at z>0.5 (2.0), conflicts with known gamma-ray bursts (GRBs) of similar X-ray luminosities. We therefore favor a jetted tidal disruption event (TDE) as the progenitor of EP240408a at z>1.0, possibly caused by the disruption of a white dwarf by an intermediate mass black hole. The alternative is that EP240408a may represent a new, previously unknown class of transient.
An Empirical Framework Characterizing the Metallicity and Star-Formation History Dependence of X-ray Binary Population Formation and Emission in Galaxies
(2024-10-25) Lehmer, Bret D.; Monson, Erik B.; Eufrasio, Rafael T.; Amiri, Amirnezam; Doore, Keith; Basu-Zych, Antara; Garofali, Kristen; Oskinova, Lidia; Andrews, Jeff J.; Antoniou, Vallia; Geda, Robel; Greene, Jenny E.; Kovlakas, Konstantinos; Lazzarini, Margaret; Richardson, Chris T.
We present a new empirical framework modeling the metallicity and star-formation history (SFH) dependence of X-ray luminous (L>10³⁶ ergs s⁻¹) point-source population luminosity functions (XLFs) in normal galaxies. We expect the X-ray point-source populations are dominated by X-ray binaries (XRBs), with contributions from supernova remnants near the low luminosity end of our observations. Our framework is calibrated using the collective statistical power of 3,731 X-ray detected point-sources within 88 Chandra-observed galaxies at D< 40 Mpc that span broad ranges of metallicity (Z≈ 0.03-2 Z⊙), SFH, and morphology (dwarf irregulars, late-types, and early-types). Our best-fitting models indicate that the XLF normalization per unit stellar mass declines by ≈2-3 dex from 10 Myr to 10 Gyr, with a slower age decline for low-metallicity populations. The shape of the XLF for luminous X-ray sources (L<10³⁸ ergs s⁻¹) significantly steepens with increasing age and metallicity, while the lower-luminosity XLF appears to flatten with increasing age. Integration of our models provide predictions for X-ray scaling relations that agree very well with past results presented in the literature, including, e.g., the Lₓ-SFR-Z relation for high-mass XRBs (HMXBs) in young stellar populations as well as the Lₓ/M⋆ ratio observed in early-type galaxies that harbor old populations of low-mass XRBs (LMXBs). The model framework and data sets presented in this paper further provide unique benchmarks that can be used for calibrating binary population synthesis models.
Hard X-Ray Spectrum of the Vela Pulsar and Its Wind Nebula Constrained by NuSTAR
(IOP, 2024-11-04) Kargaltsev, Oleg; Hare, Jeremy; Lange, Alexander
We present the analysis of 200 ks NuSTAR observation of the Vela pulsar and the pulsar wind nebula (PWN). The phase-resolved spectra corresponding to two main peaks in the folded pulse profile differ significantly. The spectrum of Peak 1 is significantly harder than that of Peak 2 in qualitative agreement with the earlier Rossi X-ray Timing Explorer results. However, for both spectra, the values of power-law (PL) fit photon indices, Γ, are noticeably larger than the previously reported values. The harder (Peak 1) spectrum has Γ = 1.10 ± 0.15, which is close to those measured for the bright inner jets of the PWN. We used the off-pulse interval to remove the emission from the pulsar and measure the compact PWN spectrum in hard X-rays. We also measured the spectrum from the southwestern region of the PWN, which is resolved by NuSTAR from the compact PWN. For both regions, we fit the NuSTAR spectra by themselves and together with the Chandra X-ray Observatory spectra. We found that the PWN spectrum (for both regions) requires a more complex model than a simple PL. The fits to compact PWN spectrum favor an exponentially cutoff PL model, with Ec ≈ 50 keV over the broken PL model. The observed synchrotron photon energies imply electrons accelerated to ≈150 TeV.
Multiwavelength study of 1eRASS J085039.9-421151 with eROSITA NuSTAR and X-shooter
(2024-11-04) Zainab, Aafia; Avakyan, Artur; Doroshenko, Victor; Thalhammer, Philipp; Sokolova-Lapa, Ekaterina; Ballhausen, Ralf; Zalot, Nicolas; Stierhof, Jakob; Haemmerich, Steven; Diez, Camille M.; Weber, Philipp; Dauser, Thomas; Berger, Katrin; Kretschmar, Peter; Pottschmidt, Katja; Pradhan, Pragati; Islam, Nazma; Maitra, Chandreyee; Coley, Joel B.; Blay, Pere; Corbet, Robin; Rothschild, Richard E.; Wood, Kent; Santangelo, Andrea; Heber, Ulrich; Wilms, Joern
The eROSITA instrument on board Spectrum-Roentgen-Gamma has completed four scans of the X-ray sky, leading to the detection of almost one million X-ray sources in eRASS1 only, including multiple new X-ray binary candidates. We report on analysis of the X-ray binary 1eRASS J085039.9-421151, using a ~55\,ks long NuSTAR observation, following its detection in each eROSITA scan. Analysis of the eROSITA and NuSTAR X-ray spectra in combination with X-shooter data of the optical counterpart provide evidence of an X-ray binary with a red supergiant (RSG) companion, confirming previous results, although we determine a cooler spectral type of M2-3, owing to the presence of TiO bands in the optical and near infrared spectra. The X-ray spectrum is well-described by an absorbed power law with a high energy cutoff typically applied for accreting high mass X-ray binaries. In addition, we detect a strong fluorescent neutral iron line with an equivalent width of ~700\,eV and an absorption edge, the latter indicating strong absorption by a partial covering component. It is unclear if the partial absorber is ionised. There is no significant evidence of a cyclotron resonant scattering feature. We do not detect any pulsations in the NuSTAR lightcurves, possibly on account of a large spin period that goes undetected due to insufficient statistics at low frequencies or potentially large absorption that causes pulsations to be smeared out. Even so, the low persistent luminosity, the spectral parameters observed (photon index, photon index, Γ<1.0), and the minuscule likelihood of detection of RSG-black hole systems, suggest that the compact object is a neutron star.
The XRISM/Resolve view of the Fe K region of Cyg X-3
(2024-11-08) XRISM Collaboration; Boissay-Malaquin, Rozenn; Hamaguchi, Kenji; Hayashi, Takayuki; Mukai, Koji; Pottschmidt, Katja; Tamura, Keisuke; Yaqoob, Tahir
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 paper we report on an observation of Cyg X-3 with the XRISM/Resolve spectrometer which provides unprecedented spectral resolution and sensitivity in the 2-10 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 Heα and Fe XXVI Lyα 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 ∼−500-600km s⁻¹. We show that the wind decomposes naturally into a relatively smooth and large scale component, perhaps originating with the background wind itself, plus a turbulent more dense structure located close to the compact object in its orbit.
NARVis: Neural Accelerated Rendering for Real-Time Scientific Point Cloud Visualization
(2024-07-26) Hegde, Srinidhi; Kullman, Kaur; Grubb, Thomas; Lait, Leslie; Guimond, Stephen; Zwicker, Matthias
Exploring scientific datasets with billions of samples in real-time visualization presents a challenge - balancing high-fidelity rendering with speed. This work introduces a novel renderer - Neural Accelerated Renderer (NAR), that uses the neural deferred rendering framework to visualize large-scale scientific point cloud data. NAR augments a real-time point cloud rendering pipeline with high-quality neural post-processing, making the approach ideal for interactive visualization at scale. Specifically, we train a neural network to learn the point cloud geometry from a high-performance multi-stream rasterizer and capture the desired postprocessing effects from a conventional high-quality renderer. We demonstrate the effectiveness of NAR by visualizing complex multidimensional Lagrangian flow fields and photometric scans of a large terrain and compare the renderings against the state-of-the-art high-quality renderers. Through extensive evaluation, we demonstrate that NAR prioritizes speed and scalability while retaining high visual fidelity. We achieve competitive frame rates of > 126 fps for interactive rendering of > 350M points (i.e., an effective throughput of > 44 billion points per second) using ∼12 GB of memory on RTX 2080 Ti GPU. Furthermore, we show that NAR is generalizable across different point clouds with similar visualization needs and the desired post-processing effects could be obtained with substantial high quality even at lower resolutions of the original point cloud, further reducing the memory requirements.

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