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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Don't torque like that. Measuring compact object magnetic fields with analytic torque models
(2025-04-11) Stierhof, J. J. R.; Sokolova-Lapa, E.; Berger, K.; Vasilopoulos, G.; Thalhammer, P.; Zalot, N.; Ballhausen, R.; Mellah, I. El; Malacaria, C.; Rothschild, R. E.; Kretschmar, P.; Pottschmidt, Katja; Wilms, J.
Context. Changes of the rotational period observed in various magnetized accreting sources are generally attributed to the interaction between the in-falling plasma and the large-scale magnetic field of the accretor. A number of models have been proposed to link these changes to the mass accretion rate, based on different assumptions on the relevant physical processes and system parameters. For X-ray binaries with neutron stars, with the help of precise measurements of the spin periods provided by current instrumentation, these models render a way to infer such parameters as the strength of the dipolar field and a distance to the system. Often, the obtained magnetic field strength values contradict those from other methods used to obtain magnetic field estimates. Aims. We want to compare the results of several of the proposed accretion models. To this end an example application of these models to data is performed. Methods. We reformulate the set of disk accretion torque models in a way that their parametrization are directly comparable. The application of the reformulated models is discussed and demonstrated using Fermi/GBM and Swift/BAT monitoring data covering several X-ray outbursts of the accreting pulsar 4U 0115+63. Results. We find that most of the models under consideration are able to describe the observations to a high degree of accuracy and with little indication for one model being preferred over the others. Yet, derived parameters from those models show a large spread. Specifically the magnetic field strength ranges over one order of magnitude for the different models. This indicates that the results are heavily influenced by systematic uncertainties.
Tracing the imprints of large-scale magnetized structure on γ rays from GRB 221009A
(2025-04-22) Das, Saikat; Razzaque, Soebur; Mirabal, Nestor; Omodei, Nicola; Murase, Kohta; Martinez-Castellanos, Israel
We search for possible GeV-TeV gamma-ray imprints of ultrahigh-energy (UHE; ≳ 0.1 EeV) cosmic ray (CR) acceleration in the large-scale structures surrounding the brightest gamma-ray burst (GRB) explosion, GRB 221009A. Using 1.25 years of post-event Fermi Large Area Telescope (LAT) data, we construct a 1 GeV – 1 TeV test-statistic (TS) map within 15 Mpc of the burst. We identify two peaks in the TS map with TS ≥ 9. The most significant peak, J1911.8+2044, exhibits gamma-ray emission in pre-burst LAT data. The other peak, J1913.2+1901, coincides with a 664.6 GeV photon recorded ∼ 191.9 days after the GRB trigger and located at about 0.75◦ from the GRB localization. The per-photon 95% containment angle for the LAT is about 0.25◦ in the 100 GeV – 1 TeV energy range. We explore two possible origins for the γ-ray emission: (1) UHECRs from GRB 221009A propagating through a magnetized cosmological volume in its vicinity, and (2) UHE or very high-energy (VHE; ≳ 100 GeV) γ-ray emission from GRB 221009A, propagating in the same volume. In both cases, electromagnetic cascade emission is induced in the structured region embedding the burst. If any TS features are related to large-scale imprints induced by cosmic rays, it might be further evidence that GRB 221009A accelerated UHECRs. However, our results show that alternative scenarios without invoking UHECRs cannot be ruled out, and the observed high-energy photon could be unrelated to GRB 221009A.
X-Ray Imaging and Spectroscopy Mission
(Oxford University Press, 2025-04-11) Tashiro, Makoto; Kelley, Richard; Watanabe, Shin; Maejima, Hironori; Reichenthal, Lillian; Toda, Kenichi; Hartz, Leslie; Santovincenzo, Andrea; Matsushita, Kyoko; Yamaguchi, Hiroya; Petre, Robert; Williams, Brian; Guainazzi, Matteo; Costantini, Elisa; Takei, Yoh; Ishisaki, Yoshitaka; Fujimoto, Ryuichi; Henegar-Leon, Joy; Sneiderman, Gary; Tomida, Hiroshi; Mori, Koji; Nakajima, Hiroshi; Terada, Yukikatsu; Holland, Matthew; Loewenstein, Michael; Miller, Eric; Sawada, Makoto; Kallman, Timothy; Kaastra, Jelle; Done, Chris; Enoto, Teruaki; Bamba, Aya; Corrales, Lia; Ueda, Yoshihiro; Kara, Erin; Zhuravleva, Irina; Fujita, Yutaka; Arai, Yoshitaka; Audard, Marc; Awaki, Hisamitsu; Ballhausen, Ralf; Baluta, Chris; Bando, Nobutaka; Behar, Ehud; Bialas, Thomas; Boissay-Malaquin, Rozenn; Brenneman, Laura; Brown, Gregory V.; Chiao, Meng; Cumbee, Renata; de Vries, Cor; den Herder, Jan-Willem; Díaz Trigo, María; DiPirro, Michael; Dotani, Tadayasu; Carrero, Jacobo Ebrero; Ebisawa, Ken; Eckart, Megan; Eckert, Dominique; Eguchi, Satoshi; Ezoe, Yuichiro; Ferrigno, Carlo; Foster, Adam; Fukazawa, Yasushi; Fukushima, Kotaro; Furuzawa, Akihiro; Gallo, Luigi; Garcia Martinez, Javier; Gorter, Nathalie; Grim, Martin; Gu, Liyi; Hagino, Kouichi; Hamaguchi, Kenji; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hell, Natalie; Hodges-Kluck, Edmund; Horiuchi, Takafumi; Hornschemeier, Ann; Hoshino, Akio; Ichinohe, Yuto; Ikuta, Chisato; Iizuka, Ryo; Ishi, Daiki; Ishida, Manabu; Ishihama, Naoki; Ishikawa, Kumi; Ishimura, Kosei; Jaffe, Tess; Katsuda, Satoru; Kanemaru, Yoshiaki; Kenyon, Steven; Kilbourne, Caroline; Kimball, Mark; Kitamoto, Shunji; Kobayashi, Shogo; Kohmura, Takayoshi; Kubota, Aya; Leutenegger, Maurice; Maeda, Yoshitomo; Markevitch, Maxim; Matsumoto, Hironori; Matsuzaki, Keiichi; McCammon, Dan; McLaughlin, Brian; McNamara, Brian; Mernier, Francois; Miko, Joseph; Miller, Jon; Minesugi, Kenji; Mitani, Shinji; Mitsuishi, Ikuyuki; Mizumoto, Misaki; Mizuno, Tsunefumi; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard; Nakazawa, Kazuhiro; Natsukari, Chikara; Ness, Jan-Uwe; Nigo, Kenichiro; Nishiyama, Mari; Nobukawa, Kumiko; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ogawa, Mina; Ogawa, Shoji; Ogorzalek, Anna; Okajima, Takashi; Okamoto, Atsushi; Ota, Naomi; Ozaki, Masanobu; Paltani, Stephane; Plucinsky, Paul; Porter, F. Scott; Pottschmidt, Katja; Quero, Jose Antonio; Sasaki, Takahiro; Sato, Kosuke; Sato, Rie; Sato, Toshiki; Sato, Yoichi; Seta, Hiromi; Shida, Maki; Shidatsu, Megumi; Shigeto, Shuhei; Shipman, Russel; Shinozaki, Keisuke; Shirron, Peter; Simionescu, Aurora; Smith, Randall; Soong, Yang; Suzuki, Hiromasa; Szymkowiak, Andrew; Takahashi, Hiromitsu; Takeo, Mai; Tamagawa, Toru; Tamura, Keisuke; Tanaka, Takaaki; Tanimoto, Atsushi; Terashima, Yuichi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi; Uchida, Hiroyuki; Uchida, Nagomi; Uchida, Yuusuke; Uchiyama, Hideki; Uno, Shinichiro; Vink, Jacco; Witthoeft, Michael; Wolfs, Rob; Yamada, Satoshi; Yamada, Shinya; Yamaoka, Kazutaka; Yamasaki, Noriko; Yamauchi, Makoto; Yamauchi, Shigeo; Yanagase, Keiichi; Yaqoob, Tahir; Yasuda, Susumu; Yoneyama, Tomokage; Yoshida, Tessei; Yukita, Miohoko
The X-Ray Imaging and Spectroscopy Mission (XRISM) is a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration (NASA) in collaboration with the European Space Agency (ESA). In addition to the three space agencies, universities and research institutes from Japan, North America, and Europe have joined to contribute to developing satellite and onboard instruments, data-processing software, and the scientific observation program. XRISM is the successor to the ASTRO-H (Hitomi) mission, which ended prematurely in 2016. Its primary science goal is to examine astrophysical problems with precise, high-resolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. It carries a 6 × 6 pixelized X-ray microcalorimeter on the focal plane of an X-ray mirror assembly (Resolve) and a co-aligned X-ray CCD camera (Xtend) that covers the same energy band over a large field of view. XRISM utilizes the Hitomi heritage, but all designs were reviewed. The attitude and orbit control system was improved in hardware and software. The spacecraft was launched from the JAXA Tanegashima Space Center on 2023 September 6 (UTC). During the in-orbit commissioning phase, the onboard components were activated. Although the gate valve protecting the Resolve sensor with a thin beryllium X-ray entrance window was not yet opened, scientific observation started in 2024 February with the planned performance verification observation program. The nominal observation program commenced with the following guest observation program beginning in 2024 September.
The response of warm absorbers to the variations in the ionizing continuum in the active galaxy NGC4051
(2025-04-11) Sadaula, Dev R.; Kallman, Timothy R.; Laha, Sibasish
We investigate the response of warm absorbers to variations in the ionizing continuum of the Seyfert 1 galaxy NGC 4051 using time-resolved X-ray observations from the Neutron Star Interior Composition Explorer (NICER). In this work, we have demonstrated we can perform time-resolved spectroscopic studies of warm absorbers of about ∼ 5500 s time resolution using NICER data. We have extracted 15 spectra for this source, corresponding to 15 different visits to the source, or pointings, each separated by a longer Earth occultation. By modeling the spectral variability of the warm absorber with the warmabs analytic model, we detect significant variations in the ionization parameter that correlate with changes in the ionizing flux. A time lag of approximately 5500 seconds is observed between the flux variations and the absorber's ionization response, suggesting that the gas is out of photoionization equilibrium during these periods. Using this time lag, we estimate the lower limit of the gas density 8.91 × 10⁶cm⁻³ and constrain the location of the warm absorber to within 7.02 × 10¹⁶ cm (∼ 0.02 parsec) from the central black hole. This study uses time-resolved spectral analysis to contribute to our understanding of the physical conditions of ionized AGN outflows, such as density and location.
The infrared counterpart and proper motion of magnetar SGR 0501+4516
(A&A, 2025-04-15) Chrimes, A. A.; Levan, A. J.; Lyman, J. D.; Borghese, A.; Dhillon, V. S.; Esposito, P.; Fraser, M.; Fruchter, A. S.; Götz, D.; Hounsell, Rebekah; Israel, G. L.; Kouveliotou, C.; Mereghetti, S.; Mignani, R. P.; Perna, R.; Rea, N.; Skillen, I.; Steeghs, D.; Tanvir, N. R.; Wiersema, K.; Wright, N. J.; Zane, S.
Aims. Soft gamma repeaters (SGRs) are highly magnetised neutron stars (magnetars) notable for their gamma-ray and X-ray outbursts. We used near-infrared (NIR) imaging of SGR 0501+4516 in the days, weeks, and years after its 2008 outburst to characterise the multi-wavelength emission, and to obtain a proper motion from our long temporal baseline observations. Methods. We present short- and long-term monitoring of the IR counterpart of SGR 0501+4516 and a measurement of its proper motion. Unlike most magnetars, the source has only moderate foreground extinction with minimal crowding. Our observations began only ∼2 hours after the first activation of SGR 0501+4516 in August 2008 and continued for ∼4 years, including two epochs of Hubble Space Telescope (HST) imaging. The proper motion constraint was improved using a third HST epoch from 10 years later. Results. The NIR and X-rays faded slowly during the first week, which was followed by a steeper power-law decay. The behaviour is satisfactorily fit by a broken power law. Three epochs of HST imaging with a 10-year baseline allowed us to determine the quiescent level and to measure a proper motion of μ = 5.4 ± 0.6 mas yr−1. This corresponds to a low transverse peculiar velocity of v ≃ 51 ± 14 km s−1 (at 2 kpc). The magnitude and direction of the proper motion rules out supernova remnant HB9 as the birth site. We can find no other supernova remnants or groups of massive stars within the region traversed by SGR 0501+4516 during its characteristic lifetime (∼20 kyr). Conclusions. Our observations of SGR 0501+4516 suggest three possibilities: that some magnetars are significantly older than expected, that their progenitors produce low supernova ejecta masses, or that they can be formed through accretion-induced collapse or low-mass neutron star mergers. Although the progenitor of SGR 0501+4516 remains unclear, we propose that SGR 0501+4516 is the best Galactic candidate for a magnetar formed through a mechanism other than massive star core-collapse.
Simulating Impacts of Electron Precipitation on Mars' Nightside Ionosphere With an Empirical Model
(American Geophysical Union, 2025) Marquette, M.; Lillis, R. J.; Pawlowski, D. J.; Chaufray, J.-Y.; Ma, Y. J.; González-Galindo, F.; Mitchell, D. L.; Halekas, J. S.; Benna, Mehdi; Elrod, M. K.; Espley, J. R.; Gruesbeck, J. R.; Curry, S. M.
With the aim of improving global simulations of the Martian ionosphere, we present an empirical model of 137 electron impact processes—including ionization, dissociation, and excitation—on the nightside of Mars, based on MAVEN in situ data collected between 2014 and 2019. The empirical model demonstrates the significant impact magnetic field conditions have on nightside ionization rates, with different magnetic topologies reversing trends previously seen in ionization dependence on magnetic field strength: closed field lines on the nightside show a decrease in ionization with stronger fields, while topologies where field lines connect to a source of plasma at one or both ends show an increase of ionization with stronger fields. This empirical model is coupled with magnetic fields from MHD simulations of the Martian magnetosphere, as input to the PCM-Mars and M-GITM thermosphere-ionosphere models, to provide a source of ionization on the nightside. Finally, we present new simulations of the global ionosphere with ionization sources on both the dayside and, for the first time, the nightside.
A Swarm of WASP Planets: Nine giant planets identified by the WASP survey
(2025-04-10) Schanche, Nicole; Hébrard, Guillaume; Stassun, Keivan G.; Hord, Benjamin J.; Barkaoui, Khalid; Bieryla, Allyson; Ciardi, David R.; Collins, Karen A.; Cameron, Andrew Collier; Hartman, Joel; Heidari, N.; Hellier, Coel; Howell, Steve B.; Lendl, Monika; McCormac, James; McLeod, Kim K.; Parviainen, Hannu; Radford, Don J.; Rajpurohit, Arvind Singh; Relles, Howard M.; Sharma, Rishikesh; Baliwal, Sanjay; Bakos, Gaspar; Barros, Susana; Bouchy, François; Burdanov, Artem Y.; Budnikova, Polina A.; Chakaraborty, Abhijit; Clark, Catherine; Delrez, Laetitia; Demangeon, O. D. S.; Diaz, Rodrigo; Donnenfield, Jonah; Everett, Mark; Gillon, Michaël; Hedges, Christina; Higuera, Jesus; Jehin, Emmanuel; Jenkins, Jon M.; Kiefer, Flavien; Laloum, Didier; Lund, Mike; Magain, Pierre; Maxted, Pierre; Mireles, Ismael; Nikitha, K. J.; Opitom, Cyrielle; Patel, Yatrik; Rose, Mark; Sousa, Sergio; Strakhov, Ivan; Strøm, Paul; Tuson, Amy; West, Richard; Winn, Joshua
The Wide Angle Search for Planets (WASP) survey provided some of the first transiting hot Jupiter candidates. With the addition of the Transiting Exoplanet Survey Satellite (TESS), many WASP planet candidates have now been revisited and given updated transit parameters. Here we present 9 transiting planets orbiting FGK stars that were identified as candidates by the WASP survey and measured to have planetary masses by radial velocity measurements. Subsequent space-based photometry taken by TESS as well as ground-based photometric and spectroscopic measurements have been used to jointly analyze the planetary properties of WASP-102 b, WASP-116 b, WASP-149 b WASP-154 b, WASP-155 b, WASP-188 b, WASP-194 b/HAT-P-71 b, WASP-195 b, and WASP-197 b. These planets have radii between 0.9 Rⱼᵤₚ and 1.4 Rⱼᵤₚ, masses between 0.1 Mⱼᵤₚ and 1.5 Mⱼᵤₚ, and periods between 1.3 and 6.6 days.
Multiwavelength observation of a candidate pulsar halo LHAASO J0621+3755 and the first X-ray detection of PSR J0622+3749
(2025-04-03) Adams, C. B.; Archer, A.; Bangale, P.; Bartkoske, J. T.; Benbow, W.; Buckley, J. H.; Chen, Y.; Christiansen, J. L.; Chromey, A. J.; Duerr, A.; Errando, M.; Godoy, M. Escobar; Falcone, A.; Feldman, S.; Feng, Q.; Fortson, L.; Furniss, A.; Hanlon, W.; Hervet, O.; Hinrichs, C. E.; Holder, J.; Humensky, T. B.; Jin, W.; Johnson, M. N.; Kaaret, P.; Kertzman, M.; Kherlakian, M.; Kieda, D.; Kleiner, T. K.; Korzoun, N.; Krennrich, F.; Kumar, S.; Kundu, S.; Lang, M. J.; Lundy, M.; Maier, G.; Millard, M. J.; Millis, J.; Mooney, C. L.; Moriarty, P.; Mukherjee, R.; Ning, W.; Ong, R. A.; Pandey, A.; Pohl, M.; Pueschel, E.; Quinn, J.; Rabinowitz, P. L.; Ragan, K.; Reynolds, P. T.; Ribeiro, D.; Rizk, L.; Roache, E.; Sadeh, I.; Saha, L.; Sembroski, G. H.; Shang, R.; Splettstoesser, M.; Tak, D.; Talluri, A. K.; Tucci, J. V.; Valverde, Janeth; Williams, D. A.; Wong, S. L.; Woo, J.; Kwong, J.; Mori, K.; Hailey, C. J.; Safi-Harb, S.; Zhang, S.; Tsuji, N.; Manconi, S.; Donato, F.; Mauro, M. Di
Pulsar halos are regions around middle-aged pulsars extending out to tens of parsecs. The large extent of the halos and well-defined central cosmic-ray accelerators make this new class of Galactic sources an ideal laboratory for studying cosmic-ray transport. LHAASO J0621+3755 is a candidate pulsar halo associated with the middle-aged gamma-ray pulsar PSR J0622+3749. We observed LHAASO J0621+3755 with VERITAS and XMM-Newton in the TeV and X-ray bands, respectively. For this work, we developed a novel background estimation technique for imaging atmospheric Cherenkov telescope observations of such extended sources. No halo emission was detected with VERITAS (0.3--10 TeV) or XMM-Newton (2--7 keV) within 1 degree and 10 arcmin around PSR J0622+3749, respectively. Combined with the LHAASO-KM2A and Fermi-LAT data, VERITAS flux upper limits establish a spectral break at ~1--10 TeV, a unique feature compared with Geminga, the most studied pulsar halo. We model the gamma-ray spectrum and LHAASO-KM2A surface brightness as inverse Compton emission and find suppressed diffusion around the pulsar, similar to Geminga. A smaller diffusion suppression zone and harder electron injection spectrum than Geminga are necessary to reproduce the spectral cutoff. A magnetic field <= 1 uG is required by our XMM-Newton observation and synchrotron spectral modeling, consistent with Geminga. Our findings support slower diffusion and lower magnetic field around pulsar halos than the Galactic averages, hinting at magnetohydrodynamic turbulence around pulsars. Additionally, we report the detection of an X-ray point source spatially coincident with PSR J0622+3749, whose periodicity is consistent with the gamma-ray spin period of 333.2 ms. The soft spectrum of this source suggests a thermal origin.
In-orbit Performance of the Soft X-ray Imaging Telescope Xtend aboard XRISM
(2025-03-26) Uchida, Hiroyuki; Mori, Koji; Tomida, Hiroshi; Nakajima, Hiroshi; Noda, Hirofumi; Tanaka, Takaaki; Murakami, Hiroshi; Suzuki, Hiromasa; Kobayashi, Shogo Benjamin; Yoneyama, Tomokage; Hagino, Kouichi; Nobukawa, Kumiko Kawabata; Uchiyama, Hideki; Nobukawa, Masayoshi; Matsumoto, Hironori; Tsuru, Takeshi Go; Yamauchi, Makoto; Hatsukade, Isamu; Odaka, Hirokazu; Kohmura, Takayoshi; Yamaoka, Kazutaka; Yoshida, Tessei; Kanemaru, Yoshiaki; Ishi, Daiki; Dotani, Tadayasu; Ozaki, Masanobu; Tsunemi, Hiroshi; Miyazaki, Keitaro; Kusunoki, Kohei; Otsuka, Yoshinori; Yokosu, Haruhiko; Yonemaru, Wakana; Ichikawa, Kazuhiro; Nakano, Hanako; Takemoto, Reo; Matsushima, Tsukasa; Urase, Reika; Kurashima, Jun; Fuchi, Kotomi; Hayakawa, Kaito; Fukuda, Masahiro; Inoue, Shun; Aoki, Yuma; Takayama, Kouta; Sako, Takashi; Yoshimoto, Marina; Shima, Kohei; Higuchi, Mayu; Ninoyu, Kaito; Aoki, Daiki; Tsunomachi, Shun; Okajima, Takashi; Ishida, Manabu; Maeda, Yoshitomo; Hayashi, Takayuki; Tamura, Keisuke; Boissay-Malaquin, Rozenn; Sato, Toshiki; Takeo, Mai; Miyamoto, Asca; Matsumoto, Gakuto; Eckart, Megan E.; Hell, Natalie; Leutenegger, Maurice A.; Hayashida, And Kiyoshi
We present a summary of the in-orbit performance of the soft X-ray imaging telescope Xtend onboard the XRISM mission, based on in-flight observation data, including first-light celestial objects, calibration sources, and results from the cross-calibration campaign with other currently-operating X-ray observatories. XRISM/Xtend has a large field of view of 38.5' x 38.5', covering an energy range of 0.4-13 keV, as demonstrated by the first-light observation of the galaxy cluster Abell 2319. It also features an energy resolution of 170--180 eV at 6 keV, which meets the mission requirement and enables to resolve He-like and H-like Fe Kα lines. Throughout the observation during the performance verification phase, we confirm that two issues identified in SXI onboard the previous Hitomi mission -- light leakage and crosstalk events -- are addressed and suppressed in the case of Xtend. A joint cross-calibration observation of the bright quasar 3C273 results in an effective area measured to be ∼420 cm²@1.5 keV and ∼310 cm²@6.0 keV, which matches values obtained in ground tests. We also continuously monitor the health of Xtend by analyzing overclocking data, calibration source spectra, and day-Earth observations: the readout noise is stable and low, and contamination is negligible even one year after launch. A low background level compared to other major X-ray instruments onboard satellites, combined with the largest grasp (Ωeff∼60 cm² degree²) of Xtend, will not only support Resolve analysis, but also enable significant scientific results on its own. This includes near future follow-up observations and transient searches in the context of time-domain and multi-messenger astrophysics.
Observable-based reformulation of time-delay interferometry
(2025-02-16) Yamamoto, Kohei; Reinhardt, Jan Niklas; Hartwig, Olaf
Spaceborne gravitational-wave observatories utilize a post-processing technique known as time-delay interferometry (TDI) to reduce the otherwise overwhelming laser frequency noise by around eight orders of magnitude. While, in its traditional form, TDI considers the spacecraft as point masses, recent studies have enhanced this simplified scenario by incorporating more realistic metrology chain models, which include onboard optical, electronic, and digital delays. These studies have updated the TDI algorithm to include onboard delays obtained from pre-launch and in-flight calibrations. Conversely, the processing scheme presented in this article naturally treats onboard delays as part of the TDI combinations: instead of having separate calibration stages, it directly expresses all delays appearing in the algorithm in terms of onboard measurements, especially pseudo-random-noise ranging (PRNR) measurements. The only onboard delays that need to be corrected in our processing scheme are PRNR delays in the digital domain, which are determined by commandable digital-signal-processing parameters; hence, they can be easily managed in post-processing. Furthermore, our processing scheme does not require a prior interspacecraft clock synchronization, and it automatically corrects for potential relative drifts between the clocks driving local phase measurement systems. The proposed observable-based processing scheme significantly strengthens the bond between TDI and the real metrology system.
NASA Innovative Advanced Concepts Phase I Final Report -- A Lunar Long-Baseline UV/Optical Imaging Interferometer: Artemis-enabled Stellar Imager (AeSI)
(2025-03-03) Carpenter, Kenneth G.; Boyajian, Tabetha; Buzasi, Derek; Clark, Jim; Creech-Eakman, Michelle; Dean, Bruce; Elliott, Ashley; Foster, Julianne; Gong, Qian; Karovska, Margarita; Kim, David; Hulberg, Jon; Leisawitz, David; Maher, Mike; Morse, Jon; Mozurkewich, Dave; Peacock, Sarah; Petro, Noah; Rau, Gioia; Scowen, Paul; Seals, Len; Smith, Walter; Smuda, Max; Sitarski, Breann; Taylor, Buddy; van Belle, Gerard; Wilkinson, Erik
This report presents the findings of a NIAC Phase I feasibility study for the Artemis-enabled Stellar Imager (AeSI), a proposed high-resolution, UV/Optical interferometer designed for deployment on the lunar surface. Its primary science goal is to image the surfaces and interiors of stars with unprecedented detail, revealing new details about their magnetic processes and dynamic evolution and enabling the creation of a truly predictive solar/stellar dynamo model. This capability will transform our understanding of stellar physics and has broad applicability across astrophysics, from resolving the cores of Active Galactic Nuclei (AGN) to studying supernovae, planetary nebulae, and the late stages of stellar evolution. By leveraging the stable vacuum environment of the Moon and the infrastructure being established for the Artemis Program, AeSI presents a compelling case for a lunar-based interferometer. In this study, the AeSI Team, working with the NASA Goddard Space Flight Center's Integrated Design Center (IDC), has firmly established the feasibility of building and operating a reconfigurable, dispersed aperture telescope (i.e., an interferometer) on the lunar surface. The collaboration produced a credible Baseline design featuring 15 primary mirrors arranged in an elliptical array with a 1 km major axis, with the potential to expand to 30 mirrors and larger array sizes through staged deployments. Additionally, this study identified numerous opportunities for optimization and the necessary trade studies to refine the design further. These will be pursued in follow-up investigations, such as a NIAC Phase II study, to advance the concept toward implementation.
Nano-Newton electrostatic force actuators for femto-Newton-sensitive measurements: System performance test in the LISA Pathfinder mission
(APS, 2024-05-22) LISA Pathfinder Collaboration; Armano, M.; Audley, H.; Baird, J.; Bassan, M.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Castelli, Eleonora; Cavalleri, A.; Cesarini, A.; Chiavegato, V.; Cruise, A. M.; Dal Bosco, D.; Danzmann, K.; De Deus Silva, M.; De Rosa, R.; Di Fiore, L.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Freschi, M.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grado, A.; Grimani, C.; Grzymisch, J.; Harrison, I.; Hartig, M. S.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C. J.; Liu, L.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; McNamara, P. W.; Mendes, J.; Mendes, L.; Meshksar, N.; Moerschell, J.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Plagnol, E.; Praplan, C.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D. I.; Russano, G.; Sala, L.; Sarra, P.; Schule-Walewski, S. L.; Slutsky, J.; Sopuerta, C. F.; Stanga, R.; Sumner, T.; ten Pierick, J.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P. J.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zanoni, C.; Zweifel, P.
Electrostatic force actuation is a key component of the system of geodesic reference test masses (TM) for the LISA orbiting gravitational wave observatory and in particular for performance at low frequencies, below 1 mHz, where the observatory sensitivity is limited by stray force noise. The system needs to apply forces of order 10?9 N while limiting fluctuations in the measurement band to levels approaching 10?15 N/Hz1/2. We present here the LISA actuation system design, based on audio-frequency voltage carrier signals, and results of its in-flight performance test with the LISA Pathfinder test mission. In LISA, TM force actuation is used to align the otherwise free-falling TM to the spacecraft-mounted optical metrology system, without any forcing along the critical gravitational wave-sensitive interferometry axes. In LISA Pathfinder, on the other hand, the actuation was used also to stabilize the TM along the critical ?? axis joining the two TM, with the commanded actuation force entering directly into the mission’s main differential acceleration science observable. The mission allowed demonstration of the full compatibility of the electrostatic actuation system with the LISA observatory requirements, including dedicated measurement campaigns to amplify, isolate, and quantify the two main force noise contributions from the actuation system, from actuator gain noise and from low frequency “in band” voltage fluctuations. These campaigns have shown actuation force noise to be a relevant, but not dominant, noise source in LISA Pathfinder and have allowed performance projections for the conditions expected in the LISA mission.
Magnetic-Induced Force Noise in LISA Pathfinder Free-Falling Test Masses
(APS, 2025-02-18) Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Castelli, Eleonora; Cavalleri, A.; Cesarini, A.; Cruise, A. M.; Danzmann, K.; de Deus Silva, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Freschi, M.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Harrison, I.; Hartig, M.-S.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C. J.; Liu, L.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; McNamara, P. W.; Mendes, J.; Mendes, L.; Meshksar, N.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D. I.; Russano, G.; Sala, L.; Serrano, D.; Slutsky, J.; Sopuerta, C. F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P. J.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zweifel, P.
LISA Pathfinder was a mission designed to test key technologies required for gravitational wave detection in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime, which corresponds to the measurement band of interest for future space-borne gravitational wave observatories. Magnetically induced forces couple to the test mass motion, introducing a contribution to the relative acceleration noise between the free-falling test masses. In this Letter we present the first complete estimate of this term of the instrument performance model.
In-depth analysis of LISA Pathfinder performance results: Time evolution, noise projection, physical models, and implications for LISA
(APS, 2024-08-21) LISA Pathfinder Collaboration; Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Castelli, Eleonora; Cavalleri, A.; Cesarini, A.; Chiavegato, V.; Cruise, A. M.; Dal Bosco, D.; Danzmann, K.; De Deus Silva, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Freschi, M.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Harrison, I.; Hartig, M. S.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johlander, B.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C. J.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; McNamara, P. W.; Mendes, J.; Mendes, L.; Meshksar, N.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Plagnol, E.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D. I.; Russano, G.; Sala, L.; Slutsky, J.; Sopuerta, C. F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zanoni, C.; Zweifel, P.
We present an in-depth analysis of the LISA Pathfinder differential acceleration performance over the entire course of its science operations, spanning approximately 500 days. We find: (1) The evolution of the Brownian noise that dominates the acceleration amplitude spectral density (ASD), for frequencies 𝑓≳1 mHz, is consistent with the decaying pressure due to the outgassing of a single gaseous species. (2) Between 𝑓=36 μ⁢Hz and 1 mHz, the acceleration ASD shows a 1/𝑓 tail in excess of the Brownian noise of almost constant amplitude, with ≃20% fluctuations over a period of a few days, with no particular time pattern over the course of the mission. (3) At the lowest considered frequency of 𝑓=18 μ⁢Hz, the ASD significantly deviates from the 1/𝑓 behavior, because of temperature fluctuations that appear to modulate a quasistatic pressure gradient, sustained by the asymmetries of the outgassing pattern. We also present the results of a projection of the observed acceleration noise on the potential sources for which we had either a direct correlation measurement or a quantitative estimate from dedicated experiments. These sources account for approximately 40% of the noise power in the 1/𝑓 tail. Finally, we analyze the possible sources of the remaining unexplained fraction and identify the possible measures that may be taken to keep those under control in LISA.
Extracting gravitational wave signals from LISA data in the presence of artifacts
(IOP Publishing, 2025-03-06) Castelli, Eleonora; Baghi, Quentin; Baker, John G.; Slutsky, Jacob; Bobin, Jérôme; Karnesis, Nikolaos; Petiteau, Antoine; Sauter, Orion; Wass, Peter; Weber, William J.
The Laser Interferometer Space Antenna (LISA) mission is being developed by ESA with NASA participation. As it has recently passed the Mission Adoption milestone, models of the instruments and noise performance are becoming more detailed, and likewise prototype data analyses must as well. Assumptions such as Gaussianity, stationarity, and data continuity are unrealistic, and must be replaced with physically motivated data simulations, and data analysis methods adapted to accommodate such likely imperfections. To this end, the LISA Data Challenges have produced datasets featuring time-varying and unequal constellation armlength, and measurement artifacts including data interruptions and instrumental transients. In this work, we assess the impact of these data artifacts on the inference of galactic binary and massive black hole properties. Our analysis shows that the treatment of noise transients and gaps is necessary for effective parameter estimation, as they substantially corrupt the analysis if unmitigated. We find that straightforward mitigation techniques can significantly if imperfectly suppress artifacts. For the Galactic Binaries, mitigation of glitches was essentially total, while mitigations of the data gaps increased parameter uncertainty by approximately 10%. For the massive black hole binaries the particularly pernicious glitches resulted in a 30% uncertainty increase after mitigations, while the data gaps can increase parameter uncertainty by up to several times. Critically, this underlines the importance of early detection of transient gravitational waves to ensure they are protected from planned data interruptions.
Artifact: Defining and Analyzing Smart Device Passive Mode
(HAL, 2025-03-17) Badolato, Christian; Kullman, Kaur; Papadakis, Nikolaos; Bhatt, Manav; Bouloukakis, Georgios; Engel, Don; Yus, Roberto
This artifact paper presents a guide for the Smart Home IoT Passive Mode Analysis tool and dataset to perform network traffic analysis (NTA) on smart home IoT devices in passive mode. The repository includes: 1) scripts and configurations for processing network traffic capture files and extracting the relevant information; 2) output data files for the experiments conducted; and 3) a link to the raw network capture dataset. The dataset contains 12GB of passive mode traffic from 32 devices across 3 testbeds; between 71 and 196 hours of traffic is present for each device.
Tilt-to-length coupling in LISA Pathfinder: Long-term stability
(APS, 2024-09-03) Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Castelli, Eleonora; Cavalleri, A.; Cesarini, A.; Cruise, A. M.; Danzmann, K.; de Deus Silva, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Freschi, M.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Harrison, I.; Hartig, M.-S.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johann, U.; Johlander, B.; Karnesis, N.; Kaune, B.; Killow, C. J.; Korsakova, N.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; McNamara, P. W.; Mendes, J.; Mendes, L.; Meshksar, N.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Plagnol, E.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D. I.; Russano, G.; Sanjuan, J.; Slutsky, J.; Sopuerta, C. F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wanner, G.; Ward, H.; Wass, P. J.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zweifel, P.
The tilt-to-length coupling during the LISA Pathfinder mission has been numerically and analytically modeled for particular time spans. In this work, we investigate the long-term stability of the coupling coefficients of this noise. We show that they drifted slowly (by 1 μm/rad and 6 ×10⁻⁶ in 100 days) and were strongly correlated to temperature changes within the satellite (8 μm/rad/K and 30×10⁻⁶ /K). Based on analytical tilt-to-length coupling models, we attribute the temperature-driven coupling changes to rotations of the test masses and small distortions in the optical setup. Particularly, our findings lead to the conclusion that LISA Pathfinder’s optical baseplate was bent during the cooldown experiment, which started in late 2016 and lasted several months.
The X-ray Integral Field Unit at the end of the Athena reformulation phase
(Springer, 2025-03-04) Peille, Philippe; Barret, Didier; Cucchetti, Edoardo; Albouys, Vincent; Piro, Luigi; Simionescu, Aurora; Cappi, Massimo; Bellouard, Elise; Cénac-Morthé, Céline; Daniel, Christophe; Pradines, Alice; Finoguenov, Alexis; Kelley, Richard; Mas-Hesse, J. Miguel; Paltani, Stéphane; Rauw, Gregor; Rozanska, Agata; Svoboda, Jiri; Wilms, Joern; Audard, Marc; Bozzo, Enrico; Costantini, Elisa; Dadina, Mauro; Dauser, Thomas; Decourchelle, Anne; den Herder, Jan-Willem; Goldwurm, Andrea; Jonker, Peter; Markowitz, Alex; Mendez, Mariano; Miniutti, Giovanni; Molendi, Silvano; Nicastro, Fabrizio; Pajot, François; Pointecouteau, Etienne; Pratt, Gabriel W.; Schaye, Joop; Vink, Jacco; Webb, Natalie; Bandler, Simon; Barbera, Marco; Ceballos, Maria Teresa; Charles, Ivan; den Hartog, Roland; Doriese, W. Bertrand; Duval, Jean-Marc; Gatti, Flavio; Jackson, Brian; Kilbourne, Caroline; Macculi, Claudio; Martin, Sylvain; Parot, Yann; Porter, Frederick; Prêle, Damien; Ravera, Laurent; Smith, Stephen; Soucek, Jan; Thibert, Tanguy; Tuominen, Eija; Acero, Fabio; Ettori, Stefano; Grosso, Nicolas; Kaastra, Jelle; Mazzotta, Pasquale; Miller, Jon; Sciortino, Salvatore; Beaumont, Sophie; D’Andrea, Matteo; de Plaa, Jelle; Eckart, Megan; Gottardi, Luciano; Leutenegger, Maurice; Lotti, Simone; Molin, Alexei; Natalucci, Lorenzo; Adil, Muhammad Qazi; Argan, Andrea; Cavazzuti, Elisabetta; Fiorini, Mauro; Khosropanah, Pourya; Medinaceli Villegas, Eduardo; Minervini, Gabriele; Perry, James; Pinsard, Frederic; Raulin, Desi; Rigano, Manuela; Roelfsema, Peter; Schwander, Denis; Terron, Santiago; Torrioli, Guido; Ullom, Joel; Zuchniak, Monika; Chaoul, Laurence; Torrejon, Jose Miguel; Brachet, Frank; Cobo, Beatriz; Durkin, Malcolm; Fioretti, Valentina; Geoffray, Hervé; Jacques, Lionel; Kirsch, Christian; Lo Cicero, Ugo; Adams, Joseph; Gloaguen, Emilie; Gonzalez, Manuel; Hull, Samuel; Jellyman, Erik; Kiviranta, Mikko; Sakai, Kazuhiro; Taralli, Emanuele; Vaccaro, Davide; van der Hulst, Paul; van der Kuur, Jan; van Leeuwen, Bert-Joost; van Loon, Dennis; Wakeham, Nicholas; Auricchio, Natalia; Brienza, Daniele; Cheatom, Oscar; Franssen, Philippe; Julien, Sabine; Le Mer, Isabelle; Moirin, David; Silva, Vitor; Todaro, Michela; Clerc, Nicolas; Coleiro, Alexis; Ptak, Andy; Puccetti, Simonetta; Surace, Christian; Abdoelkariem, Shariefa; Adami, Christophe; Aicardi, Corinne; André, Jérôme; Angelinelli, Matteo; Anvar, Shebli; Arnaldi, Luis Horacio; Attard, Anthony; Audley, Damian; Bancel, Florian; Banks, Kimberly; Bernard, Vivian; Bij de Vaate, Jan Geralt; Bonino, Donata; Bonnamy, Anthony; Bonny, Patrick; Boreux, Charles; Bounab, Ayoub; Brigitte, Maïmouna; Bruijn, Marcel; Brysbaert, Clément; Bulgarelli, Andrea; Calarco, Simona; Camus, Thierry; Canourgues, Florent; Capobianco, Vito; Cardiel, Nicolas; Celasco, Edvige; Chen, Si; Chervenak, James; Chiarello, Fabio; Clamagirand, Sébastien; Coeur-Joly, Odile; Corcione, Leonardo; Coriat, Mickael; Coulet, Anais; Courty, Bernard; Coynel, Alexandre; D’Ai, Antonino; Dambrauskas, Eugenio; D’anca, Fabio; Dauner, Lea; De Gerone, Matteo; DeNigris, Natalie; Dercksen, Johannes; de Wit, Martin; Dieleman, Pieter; DiPirro, Michael; Doumayrou, Eric; Duband, Lionel; Dubbeldam, Luc; Dupieux, Michel; Dupourqué, Simon; Durand, Jean Louis; Eckert, Dominique; Ferrando, Philippe; Ferrari Barusso, Lorenzo; Finkbeiner, Fred; Fiocchi, Mariateresa; Fossecave, Hervé; Gabici, Stefano; Gallucci, Giovanni; Gant, Florent; Gao, Jian-Rong; Gastaldello, Fabio; Genolet, Ludovic; Ghizzardi, Simona; Giovannini, Elisa; Giustini, Margherita; Givaudan, Alain; Godet, Olivier; Gomez, Alicia; Gonzalez, Raoul; Gozaliasl, Ghassem; Grandsire, Laurent; Granena, David; Gros, Michel; Guerin, Corentin; Guilhem, Emmanuel; Guizzo, Gian Paolo; Gu, Liyi; Irwin, Kent; Jacquey, Christian; Janiuk, Agnieszka; Jaubert, Jean; Jolly, Antoine; Jourdan, Thierry; Knödlseder, Jürgen; König, Ole; Korb, Andrew; Kreykenbohm, Ingo; Lafforgue, David; Lan, Radek; Larrieu, Maélyss; Laudet, Philippe; Laurent, Philippe; Laurent, Sylvain; Laurenza, Monica; Le Cam, Maël; Lesrel, Jean; Ligori, Sebastiano; Lorenz, Maximilian; Luminari, Alfredo; Madsen, Kristin; Maisonnave, Océane; Marelli, Lorenzo; Marty, Wilfried; Massida, Zoé; Massonet, Didier; Maussang, Irwin; Merino Alonso, Pablo Eleazar; Mesquida, Jean; Mineo, Teresa; Montinaro, Nicola; Murat, David; Nagayoshi, Kenichiro; Nazé, Yaël; Noguès, Loïc; Nouals, François; Ortega, Cristina; Panessa, Francesca; Parodi, Luigi; Piconcelli, Enrico; Pinto, Ciro; Porquet, Delphine; Prouvé, Thomas; Punch, Michael; Rioland, Guillaume; Riollet, Marc-Olivier; Rodriguez, Louis; Roig, Anton; Roncarelli, Mauro; Roucayrol, Lionel; Roudil, Gilles; Ruiz de Ocenda, Lander; Sciortino, Luisa; Simonella, Olivier; Sordet, Michael; Taubenschuss, Ulrich; Terrasa, Guilhem; Terrier, Régis; Ubertini, Pietro; Uhlir, Ludek; Uslenghi, Michela; van Weers, Henk; Varisco, Salvatore; Varniere, Peggy; Volpe, Angela; Walmsley, Gavin; Wise, Michael; Wolnievik, Andreas; Wo?niak, Grzegorz
The Athena mission entered a redefinition phase in July 2022, driven by the imperative to reduce the mission cost at completion for the European Space Agency below an acceptable target, while maintaining the flagship nature of its science return. This notably called for a complete redesign of the X-ray Integral Field Unit (X-IFU) cryogenic architecture towards a simpler active cooling chain. Passive cooling via successive radiative panels at spacecraft level is now used to provide a 50 K thermal environment to an X-IFU owned cryostat. 4.5 K cooling is achieved via a single remote active cryocooler unit, while a multi-stage Adiabatic Demagnetization Refrigerator ensures heat lift down to the 50 mK required by the detectors. Amidst these changes, the core concept of the readout chain remains robust, employing Transition Edge Sensor microcalorimeters and a SQUID-based Time-Division Multiplexing scheme. Noteworthy is the introduction of a slower pixel. This enables an increase in the multiplexing factor (from 34 to 48) without compromising the instrument energy resolution, hence keeping significant system margins to the new 4 eV resolution requirement. This allows reducing the number of channels by more than a factor two, and thus the resource demands on the system, while keeping a 4’ field of view (compared to 5’ before). In this article, we will give an overview of this new architecture, before detailing its anticipated performances. Finally, we will present the new X-IFU schedule, with its short term focus on demonstration activities towards a mission adoption in early 2027
The temperature and metallicity distributions of the ICM: insights with TNG-Cluster for XRISM-like observations
(2025-03-03) Chatzigiannakis, Dimitris; Pillepich, Annalisa; Simionescu, Aurora; Truong, Nhut; Nelson, Dylan
The new era of high-resolution X-ray spectroscopy will significantly improve our understanding of the intra-cluster medium (ICM) by providing precise constraints on its underlying physical properties. However, spectral fitting requires reasonable assumptions on the thermal and chemical distributions of the gas. We use the output of TNG-Cluster, the newest addition to the IllustrisTNG suite of cosmological magnetohydrodynamical simulations, to provide theoretical expectations for the multi-phase nature of the ICM across hundreds of z=0 clusters (M₅₀₀c= 10¹⁴.⁰⁻¹⁵.³ M⊙) based upon a realistic model for galaxy formation and evolution. We create and analyse, in an observer-like manner, end-to-end XRISM/Resolve mock observations towards cluster centres. We then systematically compare the intrinsic properties of the simulated gas with the inferred ones from spectral fitting via a variety of commonly used spectral-emission models. Our analysis suggests that models with a distribution of temperatures, such as bvlognorm and bvgadem, better describe the complex thermal structure of the ICM, as predicted by TNG-Cluster, but incur biases of 0.5-2 keV (16th-84th percentiles). The 1T bvapec is too simplistic for the predicted broad temperature distributions, while a 2T double bvapec model systematically fails to capture the input temperature structure. However, all spectral emission models systematically underestimate the Fe abundance of the central ICM by ~0.1 Solar (~ 20 per cent) primarily due to projection effects. Selecting only strong cool core clusters leads to minor improvements on inference quality, removing the majority of outliers but maintaining similar overall biases and cluster-to-cluster scatter.
The Proxima Centauri Campaign—First Constraints on Millimeter Flare Rates from ALMA
(AAS, 2025-03-17) Burton, Kiana; MacGregor, Meredith A.; Osten, Rachel A.; Howard, Ward S.; Weinberger, Alycia J.; Shkolnik, Evgenya; Wilner, David J.; Forbrich, Jan; Barclay, Thomas
Proxima Centauri (Cen) has been the subject of many flaring studies due to its proximity and potential to host habitable planets. The discovery of millimeter flares from this M dwarf with Atacama Large Millimeter/submillimeter Array (ALMA) has opened a new window into the flaring process and the space-weather environments of exoplanets like Proxima b. Using a total of ~50 hr of ALMA observations of Proxima Cen at 1.3 mm (233 GHz), we add a new piece to the stellar flaring picture and report the first cumulative flare frequency distribution (FFD) at millimeter wavelengths of any M dwarf. We detect 463 flares ranging from energies 10²⁴ to 10²⁷ erg. The brightest and most energetic flare in our sample reached a flux density of 119 ± 7 mJy, increasing by a factor of 1000× the quiescent flux, and reaching an energy of 10²⁷ erg in the ALMA bandpass, with t₁/₂ ≈ 16 s. From a log–log linear regression fit to the FFD, we obtain a power-law index of αFFD = 2.92 ± 0.02, much steeper than αFFD values (~2) observed at X-ray to optical wavelengths. If millimeter flare rates are predictive of flare rates at extreme-UV wavelengths, the contribution of small flares to the radiation environment of Proxima b may be much higher than expected based on the shallower power-law slopes observed at optical wavelengths.

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