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

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http://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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X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630–47 Challenges the Standard Thin Accretion Disk Scenario
(AAS, 2024-03-20) Ratheesh, Ajay; Dovčiak, Michal; Krawczynski, Henric; Podgorný, Jakub; Marra, Lorenzo; Veledina, Alexandra; Suleimanov, Valery F.; Cavero, Nicole Rodriguez; Steiner, James F.; Svoboda, Jiří; Marinucci, Andrea; Bianchi, Stefano; Negro, Michela; Matt, Giorgio; Tombesi, Francesco; Poutanen, Juri; Ingram, Adam; Taverna, Roberto; West, Andrew; Karas, Vladimir; Ursini, Francesco; Soffitta, Paolo; Capitanio, Fiamma; Viscolo, Domenico; Manfreda, Alberto; Muleri, Fabio; Parra, Maxime; Beheshtipour, Banafsheh; Chun, Sohee; Cibrario, Nicolò; Lalla, Niccolò Di; Fabiani, Sergio; Hu, Kun; Kaaret, Philip; Loktev, Vladislav; Mikušincová, Romana; Mizuno, Tsunefumi; Omodei, Nicola; Petrucci, Pierre-Olivier; Puccetti, Simonetta; Rankin, John; Zane, Silvia; Zhang, Sixuan; Agudo, Iván; Antonelli, Lucio A.; Bachetti, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; Costa, Enrico; Rosa, Alessandra De; Monte, Ettore Del; Gesu, Laura Di; Marco, Alessandro Di; Donnarumma, Immacolata; Doroshenko, Victor; Ehlert, Steven R.; Enoto, Teruaki; Evangelista, Yuri; Ferrazzoli, Riccardo; Garcia, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Jorstad, Svetlana G.; Kislat, Fabian; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Monaca, Fabio La; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Marin, Frédéric; Marscher, Alan P.; Marshall, Herman L.; Massaro, Francesco; Mitsuishi, Ikuyuki; Ng, Stephen C.-Y.; O’Dell, Stephen L.; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Pesce-Rollins, Melissa; Pilia, Maura; Possenti, Andrea; Ramsey, Brian D.; Roberts, Oliver J.; Romani, Roger W.; Sgrò, Carmelo; Slane, Patrick; Spandre, Gloria; Swartz, Douglas A.; Tamagawa, Toru; Tavecchio, Fabrizio; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; Wu, Kinwah; Xie, Fei
A large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630–47. The highly significant detection (at ≈50σ confidence level) of an unexpectedly high polarization, rising from ~6% at 2 keV to ~10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities.
An in-depth analysis of the variable cyclotron lines in GX 301−2
(2024-03-25) Zalot, Nicolas; Sokolova-Lapa, Ekaterina; Stierhof, Jakob; Ballhausen, Ralf; Zainab, Aafia; Pottschmidt, Katja; Fürst, Felix; Thalhammer, Philipp; Islam, Nazma; Diez, Camille M.; Kretschmar, Peter; Berger, Katrin; Rothschild, Richard; Malacaria, Christian; Pradhan, Pragati; Wilms, Jörn
Context. The High-Mass X-ray Binary (HMXB) system GX 301−2 is a persistent source with a well-known variable cyclotron line centered at 35 keV. Recently, a second cyclotron line at 50 keV has been reported with a presumably different behavior than the 35 keV line. Aims. We investigate the presence of the newly discovered cyclotron line in the phase-averaged and phase-resolved spectra at higher luminosities than before. We further aim to determine the pulse-phase variability of both lines. Methods. We analyze a NuSTAR observation of GX 301−2 covering the pre-periastron flare, where the source luminosity reached its peak of ~4 × 10³⁷ erg s⁻¹ in the 5-50 keV range. We analyze the phase-averaged spectra in the NuSTAR energy range from 3.5−79 keV for both the complete observation and three time segments of it. We further analyze the phase-resolved spectra and the pulse-phase variability of continuum and cyclotron line parameters. Results. We confirm that the description of the phase-averaged spectrum requires a second absorption feature at 51.5⁺¹.¹₋₁.₀ keV besides the established line at 35 keV. The statistical significance of this feature in the phase-averaged spectrum is >99.999%. We further find that the 50 keV cyclotron line is present in three of eight phase bins. Conclusions. Based on the results of our analysis, we confirm that the detected absorption feature is very likely to be a cyclotron line. We discuss a variety of physical scenarios which could explain the proposed anharmonicity, but also outline circumstances under which the lines are harmonically related. We further present the cyclotron line history of GX 301−2 and evaluate concordance among each other. We also discuss an alternative spectral model including cyclotron line emission wings.
3D Kinematics of Stellar SiO Masers in the Galactic Center
(AAS, 2022-03-15) Paine, Jennie; Darling, Jeremy
We present 3D velocity measurements and acceleration limits for stars within a few parsec of the Galactic Center (GC) black hole, Sgr A*, based on observations of 43 and 86 GHz circumstellar maser emission. Observations were taken with the Very Large Array in 2013, 2014, and 2020 and with the Atacama Large Millimeter/submillimeter Array in 2015 and 2017. We detect 28 masers in total, of which four are new detections. Combining these data with extant maser astrometry, we calculate stellar proper motions and accelerations with uncertainties as low as ∼10 μas yr⁻¹ and 0.5 μas yr⁻², respectively, corresponding to approximately 0.5 km s⁻¹ and 0.04 km s⁻¹ yr⁻¹ at a distance of 8 kpc. We measure radial velocities from maser spectra with ∼0.5 km s⁻¹ uncertainties, though the precision and accuracy of such measurements for deducing the underlying stellar velocities are limited by the complex spectral profiles of some masers. We therefore measure radial acceleration limits with typical uncertainties of ∼0.1 km s⁻¹ yr⁻¹. We analyze the resulting 3D velocities and accelerations with respect to expected motions resulting from models of the mass distribution in the GC.
Secular Extragalactic Parallax: Measurement Methods and Predictions for Gaia
(AAS, 2020-02-24) Paine, Jennie; Darling, Jeremy; Graziani, Romain; Courtois, Hèléne M.
Secular extragalactic parallax caused by the solar system's velocity relative to the cosmic microwave background rest frame may be observable as a dipole proper motion field with amplitude 78 μas yr⁻¹ Mpc. Nearby galaxies also exhibit proper motions caused by their transverse peculiar velocities that prevent detection of secular parallax for any single galaxy, although a statistical detection may be made instead. Such a detection could constrain the local Hubble parameter. We present methods to measure secular parallax using correlated extragalactic proper motions and find a first limit on the secular parallax amplitude using proper motions of 232 nearby galaxies from Gaia Data Release 2. The recovered dipole has an insignificant upper limit of 3500 μas yr⁻¹ Mpc. This measurement will be improved by a larger sample size and reduced proper motion uncertainties in future data releases. Using the local peculiar velocity field derived from Cosmicflows-3, we simulate galaxy proper motions and predict that a significant detection (5–10σ) of the secular parallax amplitude will be possible by Gaia's end of mission. The detection does not correspond to a constraint on the Hubble parameter because it depends on nearby (<5 Mpc), bright (G < 15 mag) galaxies and the underlying peculiar motion dipole. We further investigate the implications of our simulations for the study of transverse peculiar velocities. The peculiar velocity field additionally results in low multipole-correlated proper motions on the order of 0.3 μas yr⁻¹ that may be confounded with other cosmological proper motion measurements, such as limits on the gravitational-wave background and the anisotropy of the Hubble expansion.
Extragalactic Proper Motions: Gravitational Waves and Cosmology
(2018-07-17) Darling, Jeremy; Truebenbach, Alexandra; Paine, Jennie
Extragalactic proper motions can reveal a variety of cosmological and local phenomena over a range of angular scales. These include observer-induced proper motions, such as the secular aberration drift caused by the solar acceleration about the Galactic Center and a secular extragalactic parallax resulting from our motion with respect to the cosmic microwave background rest frame. Cosmological effects include anisotropic expansion, transverse peculiar velocities induced by large scale structure, and the real-time evolution of the baryon acoustic oscillation. Long-period gravitational waves can deflect light rays, producing an apparent quadrupolar proper motion signal. We review these effects, their imprints on global correlated extragalactic proper motions, their expected amplitudes, the current best measurements (if any), and predictions for Gaia. Finally, we describe a possible long-baseline ngVLA program to measure or constrain these proper motion signals. In most cases, the ngVLA can surpass or complement the expected end-of-mission performance of the Gaia mission.
Astrometric Limits on the Stochastic Gravitational Wave Background
(AAS, 2018-07-11) Darling, Jeremy; Truebenbach, Alexandra E.; Paine, Jennie
The canonical methods for gravitational wave detection are ground- and space-based laser interferometry, pulsar timing, and polarization of the cosmic microwave background. But as has been suggested by numerous investigators, astrometry offers an additional path to gravitational wave detection. Gravitational waves deflect light rays of extragalactic objects, creating apparent proper motions in a quadrupolar (and higher-order modes) pattern. Astrometry of extragalactic radio sources is sensitive to gravitational waves with frequencies between roughly 10⁻¹⁸ and 10⁻⁸ Hz (H₀ and 1/3 yr⁻¹), overlapping and bridging the pulsar timing and CMB polarization regimes. We present a methodology for astrometric gravitational wave detection in the presence of large intrinsic uncorrelated proper motions (i.e., radio jets). We obtain 95% confidence limits on the stochastic gravitational wave background using 711 radio sources, ΩGW < 0.0064, and using 508 radio sources combined with the first Gaia data release: ΩGW < 0.011. These limits probe gravitational wave frequencies 6 × 10⁻¹⁸ Hz ≲ f ≲ 1 × 10⁻⁹ Hz. Using a WISE-Gaia catalog of 567,721 AGN, we predict a limit expected from Gaia alone of ΩGW < 0.0006, which is significantly higher than was originally forecast. Incidentally, we detect and report on 22 new examples of optical superluminal motion with redshifts 0.13–3.89.
The Gaia–WISE Extragalactic Astrometric Catalog
(AAS, 2018-06-01) Paine, Jennie; Darling, Jeremy; Truebenbach, Alexandra
The Gaia mission has detected a large number of active galactic nuclei (AGNs) and galaxies, but these objects must be identified among the thousandfold more numerous stars. Extant astrometric AGN catalogs do not have the uniform sky coverage required to detect and characterize the all-sky, low-multipole proper motion signals produced by the barycenter motion, gravitational waves, and cosmological effects. To remedy this, we present an all-sky sample of 567,721 AGNs in Gaia Data Release 1, selected using WISE two-color criteria. The catalog has fairly uniform sky coverage beyond the Galactic plane, with a mean density of 12.8 AGNs per square degree. The objects have magnitudes ranging from G = 8.8 down to Gaia's magnitude limit, G = 20.7. The catalog is approximately 50% complete but suffers from low stellar contamination, roughly 0.2%. We predict that the end-of-mission Gaia proper motions for this catalog will enable detection of the secular aberration drift to high significance (23σ) and will place an upper limit on the anisotropy of the Hubble expansion of about 2%.
THE GEOMETRY OF THE INFRARED AND X-RAY OBSCURER IN A DUSTY HYPERLUMINOUS QUASAR
(AAS, 2016-10-27) Farrah, Duncan; BalokoviĆ, Mislav; Stern, Daniel; Harris, Kathryn; Paine, Jennie; et al
We study the geometry of the active galactic nucleus (AGN) obscurer in IRAS 09104+4109, an IR-luminous, radio-intermediate FR-I source at z = 0.442, using infrared data from Spitzer and Herschel, X-ray data from NuSTAR, Swift, Suzaku, and Chandra, and an optical spectrum from Palomar. The infrared data imply a total rest-frame 1–1000 μm luminosity of 5.5 × 10⁴⁶ erg s⁻¹ and require both an AGN torus and a starburst model. The AGN torus has an anisotropy-corrected IR luminosity of 4.9 × 10⁴⁶ erg s⁻¹ and a viewing angle and half-opening angle both of approximately 36° from pole-on. The starburst has a star formation rate of (110 ± 34) M⊙ yr⁻¹ and an age of <50 Myr. These results are consistent with two epochs of luminous activity in IRAS 09104+4109: one approximately 150 Myr ago, and one ongoing. The X-ray data suggest a photon index of Γ ≃ 1.8 and a line-of-sight column density of Nₕ ≃ 5 × 10²³ cm⁻². This argues against a reflection-dominated hard X-ray spectrum, which would have implied a much higher Nₕ and luminosity. The X-ray and infrared data are consistent with a bolometric AGN luminosity of L₆ₒₗ ∼ (0.5–2.5) × 10⁴⁷ erg s⁻¹. The X-ray and infrared data are further consistent with coaligned AGN obscurers in which the line of sight "skims" the torus. This is also consistent with the optical spectra, which show both coronal iron lines and broad lines in polarized but not direct light. Combining constraints from the X-ray, optical, and infrared data suggest that the AGN obscurer is within a vertical height of 20 pc, and a radius of 125 pc, of the nucleus.
An Updated Reference Frame for the Galactic Inner Parsec
(AAS, 2023-09-25) Darling, Jeremy; Paine, Jennie; Reid, Mark J.; Menten, Karl M.; Sakai, Shoko; Ghez, Andrea
Infrared observations of stellar orbits about Sgr A* probe the mass distribution in the inner parsec of the Galaxy and provide definitive evidence for the existence of a massive black hole. However, the infrared astrometry is relative and is tied to the radio emission from Sgr A* using stellar SiO masers that coincide with infrared-bright stars. To support and improve this two-step astrometry, we present new astrometric observations of 15 stellar SiO masers within 2 pc of Sgr A*. Combined with legacy observations spanning 25.8 yr, we reanalyze the relative offsets of these masers from Sgr A* and measure positions and proper motions that are significantly improved compared to the previously published reference frame. Maser positions are corrected for epoch-specific differential aberration, precession, nutation, and solar gravitational deflection. Omitting the supergiant IRS 7, the mean position uncertainties are 0.46 mas and 0.84 mas in R.A. and decl., and the mean proper motion uncertainties are 0.07 mas yr⁻¹ and 0.12 mas yr⁻¹, respectively. At a distance of 8.2 kpc, these correspond to position uncertainties of 3.7 and 6.9 au and proper motion uncertainties of 2.7 and 4.6 km s⁻¹. The reference frame stability, the uncertainty in the variance-weighted mean proper motion of the maser ensemble, is 8 μas yr⁻¹ (0.30 km s⁻¹) in R.A. and 11 μas yr⁻¹ (0.44 km s⁻¹) in decl., which represents a 2.3-fold improvement over previous work and a new benchmark for the maser-based reference frame.
Adiabatic evolution due to the conservative scalar self-force during orbital resonances
(APS, 2022-09-23) Nasipak, Zachary
We calculate the scalar self-force experienced by a scalar point-charge orbiting a Kerr black hole along rθ-resonant geodesics. We use the self-force to calculate the averaged rate of change of the charge’s orbital energy hE_i, angular momentum hL_ zi, and Carter constant hQ_ i, which together capture the leading-order adiabatic, secular evolution of the point-charge. Away from resonances, only the dissipative (time antisymmetric) components of the self-force contribute to hE_i, hL_ zi, and hQ_ i. We demonstrate, using a new numerical code, that during rθ resonances conservative (time symmetric) scalar perturbations also contribute to hQ_ i and, thus, help drive the adiabatic evolution of the orbit. Furthermore, we observe that the relative impact of these conservative contributions to hQ_ i is particularly strong for eccentric 2∶3 resonances. These results provide the first conclusive numerical evidence that conservative scalar perturbations of Kerr spacetime are nonintegrable during rθ resonances.
Sensor noise in LISA Pathfinder: An extensive in-flight review of the angular and longitudinal interferometric measurement system
(APS, 2022-10-03) Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; 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.; Flatscher, R.; Freschi, M.; García, A.; Gerndt, R.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Guzman, F.; Harrison, I.; Hartig, M.-S.; Hechenblaikner, G.; 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.; Monsky, A.; 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.; Steier, F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wand, V.; Wanner, G.; Ward, H.; Wass, P. J.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zweifel, P.
In a previous article [1], we have reported on the first subpicometer interferometer flown in space as part of ESA’s LISA Pathfinder mission, and have shown the residual sensor noise to be on the level of 32.0⁺².⁴₋₁.₇ fm/√Hz. This review provides a deeper and more complete overview of the full system and its interferometric mission performance under varying operational conditions, allowing a much more detailed view on the noise model. We also include the optical measurements of rotations through differential wave front sensing (DWS), which reached a sensitivity of as good as 100 prad/√Hz. We present more evidence for the long-term stability of the interferometric performance and components. This proves a solid foundation for future interferometry in space such as the LISA mission.
Transient acceleration events in LISA Pathfinder data: Properties and possible physical origin
(APS, 2022-09-12) 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.; Sarra, P.; 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 transient events, or glitches, detected at a rate of about one per day in the differential acceleration data of LISA Pathfinder. We show that these glitches fall in two rather distinct categories: fast transients in the interferometric motion readout on one side, and true force transient events on the other. The former are fast and rare in ordinary conditions. The second may last from seconds to hours and constitute the majority of the glitches. We present an analysis of the physical and statistical properties of both categories, including a cross-analysis with other time series like magnetic fields, temperature, and other dynamical variables. Based on these analyses we discuss the possible sources of the force glitches and identify the most likely, among which the outgassing environment surrounding the test-masses stands out. We discuss the impact of these findings on the LISA design and operation, and some risk mitigation measures, including experimental studies that may be conducted on the ground, aimed at clarifying some of the questions left open by our analysis.
Charging of free-falling test masses in orbit due to cosmic rays: Results from LISA Pathfinder
(APS, 2023-03-22) 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.; Killow, C. J.; Korsakova, N.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martino, J.; Martin-Polo, L.; Martin-Porqueras, F.; 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.; Slutsky, J.; Sopuerta, C. F.; Sumner, T. J.; 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.
A comprehensive summary of the measurements made to characterize test-mass charging due to the space environment during the LISA Pathfinder mission is presented. Measurements of the residual charge of the test mass after release by the grabbing and positioning mechanism show that the initial charge of the test masses was negative after all releases, leaving the test mass with a potential in the range from -12 to -512. Variations in the neutral test-mass charging rate between 21.7 and 30.7 es⁻¹ were observed over the course of the 17-month science operations produced by cosmic ray flux changes including a Forbush decrease associated with a small solar energetic particle event. A dependence of the cosmic ray charging rate on the test-mass potential between -30.2 and -40.3 es⁻¹ V⁻¹ was observed resulting in an equilibrium test-mass potential between 670 and 960 mV, and this is attributed to a contribution to charging from low-energy electrons emitted from the gold surfaces of the gravitational reference sensor. Data from the onboard particle detector show a reliable correlation with the charging rate and with other environmental monitors of the cosmic ray flux. This correlation is exploited to extrapolate test-mass charging rates to a 20-year period giving useful insight into the expected range of charging rate that may be observed in the LISA mission.
Tilt-to-length coupling in LISA Pathfinder: A data analysis
(APS, 2023-11-03) 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.; Tevlin, L.; 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.
We present a study of the tilt-to-length coupling noise during the LISA Pathfinder mission and how it depended on the system’s alignment. Tilt-to-length coupling noise is the unwanted coupling of angular and lateral spacecraft or test mass motion into the primary interferometric displacement readout. It was one of the major noise sources in the LISA Pathfinder mission and is likewise expected to be a primary noise source in LISA. We demonstrate here that a recently derived and published analytical model describes the dependency of the LISA Pathfinder tilt-to-length coupling noise on the alignment of the two freely falling test masses. This was verified with the data taken before and after the realignments performed in March (engineering days) and June 2016, and during a two-day experiment in February 2017 (long cross-talk experiment). The latter was performed with the explicit goal of testing the tilt-to-length coupling noise dependency on the test mass alignment. Using the analytical model, we show that all realignments performed during the mission were only partially successful and explain the reasons why. In addition to the analytical model, we computed another physical tilt-to-length coupling model via a minimizing routine making use of the long cross-talk experiment data. A similar approach could prove useful for the LISA mission.
NanoNewton electrostatic force actuators for femtoNewton-sensitive measurements: system performance test in the LISA Pathfinder mission
(2023-12-30) 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.; Bosco, D. Dal; Danzmann, K.; Silva, M. De Deus; De Rosa, R.; Di Fiore, L.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferroni, L. Ferraioli 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.; Pierick, J. ten; 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.
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/H¹/² 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 x 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.
Kinematics in the Galactic Center with SiO masers
(Cambridge University Press, 2024-02-07) Paine, Jennie; Darling, Jeremy
Stellar SiO masers are found in the atmospheres of asymptotic giant branch (AGB) stars with several maser transitions observed around 43 and 86 GHz. At least 28 SiO maser stars have been detected within ?2 pc projected distance from Sgr A* by the Very Large Array (VLA) and Atacama Millimeter/submillimeter Array (ALMA). A subset of these masers have been studied for several decades and form the basis of the radio reference frame that anchors the reference frame for infrared stars in the Galactic Center (GC). We present new observations of the GC masers from VLA and ALMA. These new data combined with extant maser astrometry provide 3D positions, velocities, and acceleration limits. The proper motions and Doppler velocities are measured with unprecedented precision for these masers. We further demonstrate how these measurements may be used to trace the stellar and dark matter mass distributions within a few pc of Sgr A*.
Adiabatic gravitational waveform model for compact objects undergoing quasicircular inspirals into rotating massive black holes
(APS, 2024-02-08) Nasipak, Zachary
We present bhpwave: a new python-based, open-source tool for generating the gravitational waveforms of stellar-mass compact objects undergoing quasicircular inspirals into rotating massive black holes. These binaries, known as extreme-mass-ratio inspirals (EMRIs), are exciting mHz gravitational wave sources for future space-based detectors such as the Laser Interferometer Space Antenna (LISA). Relativistic models of EMRI gravitational wave signals are necessary to unlock the full scientific potential of mHz detectors, yet few open-source EMRI waveform models exist. Thus we built bhpwave, which uses the adiabatic approximation from black hole perturbation theory to rapidly construct gravitational waveforms based on the leading-order inspiral dynamics of the binary. In this work, we present the theoretical and numerical foundations underpinning bhpwave. We also demonstrate how bhpwave can be used to assess the impact of EMRI modeling errors on LISA gravitational wave data analysis. In particular, we find that for retrograde orbits and slowly spinning black holes we can mismodel the gravitational wave phasing by as much as ~10 radians without significantly biasing EMRI parameter estimation.
LISA Definition Study Report
(2024-02-12) Colpi, Monica; Danzmann, Karsten; Hewitson, Martin; Holley-Bockelmann, Kelly; Jetzer, Philippe; Nelemans, Gijs; Petiteau, Antoine; Shoemaker, David; Sopuerta, Carlos; Stebbins, Robin; Tanvir, Nial; Ward, Henry; Weber, William Joseph; Thorpe, Ira; Daurskikh, Anna; Deep, Atul; Núñez, Ignacio Fernández; Marirrodriga, César García; Gehler, Martin; Halain, Jean-Philippe; Jennrich, Oliver; Lammers, Uwe; Larrañaga, Jonan; Lieser, Maike; Lützgendorf, Nora; Martens, Waldemar; Mondin, Linda; Niño, Ana Piris; Amaro-Seoane, Pau; Sedda, Manuel Arca; Auclair, Pierre; Babak, Stanislav; Baghi, Quentin; Baibhav, Vishal; Baker, Tessa; Bayle, Jean-Baptiste; Berry, Christopher; Berti, Emanuele; Boileau, Guillaume; Bonetti, Matteo; Brito, Richard; Buscicchio, Riccardo; Calcagni, Gianluca; Capelo, Pedro R.; Caprini, Chiara; Caputo, Andrea; Castelli, Eleonora; Chen, Hsin-Yu; Chen, Xian; Chua, Alvin; Davies, Gareth; Derdzinski, Andrea; Domcke, Valerie Fiona; Doneva, Daniela; Dvorkin, Irna; Ezquiaga, Jose María; Gair, Jonathan; Haiman, Zoltan; Harry, Ian; Hartwig, Olaf; Hees, Aurelien; Heffernan, Anna; Husa, Sascha; Izquierdo, David; Karnesis, Nikolaos; Klein, Antoine; Korol, Valeriya; Korsakova, Natalia; Kupfer, Thomas; Laghi, Danny; Lamberts, Astrid; Larson, Shane; Jeune, Maude Le; Lewicki, Marek; Littenberg, Tyson; Madge, Eric; Mangiagli, Alberto; Marsat, Sylvain; Vilchez, Ivan Martin; Maselli, Andrea; Mathews, Josh; van de Meent, Maarten; Muratore, Martina; Nardini, Germano; Pani, Paolo; Peloso, Marco; Pieroni, Mauro; Pound, Adam; Quelquejay-Leclere, Hippolyte; Ricciardone, Angelo; Rossi, Elena Maria; Sartirana, Andrea; Savalle, Etienne; Sberna, Laura; Sesana, Alberto; Shoemaker, Deirdre; Slutsky, Jacob; Sotiriou, Thomas; Speri, Lorenzo; Staab, Martin; Steer, Danièle; Tamanini, Nicola; Tasinato, Gianmassimo; Torrado, Jesus; Torres-Orjuela, Alejandro; Toubiana, Alexandre; Vallisneri, Michele; Vecchio, Alberto; Volonteri, Marta; Yagi, Kent; Zwick, Lorenz
The Laser Interferometer Space Antenna (LISA) is the first scientific endeavour to detect and study gravitational waves from space. LISA will survey the sky for Gravitational Waves in the 0.1 mHz to 1 Hz frequency band which will enable the study of a vast number of objects ranging from Galactic binaries and stellar mass black holes in the Milky Way, to distant massive black-hole mergers and the expansion of the Universe. This definition study report, or Red Book, presents a summary of the very large body of work that has been undertaken on the LISA mission over the LISA definition phase.
Detection and characterization of instrumental transients in LISA Pathfinder and their projection to LISA
(APS, 2022-02-16) Baghi, Quentin; Korsakova, Natalia; Slutsky, Jacob; Castelli, Eleonora; Karnesis, Nikolaos; Bayle, Jean-Baptiste
The LISA Pathfinder (LPF) mission succeeded outstandingly in demonstrating key technological aspects of future space-borne gravitational-wave detectors, such as the Laser Interferometer Space Antenna (LISA). Specifically, LPF demonstrated with unprecedented sensitivity the measurement of the relative acceleration of two free-falling cubic test masses. Although most disruptive nongravitational forces have been identified and their effects mitigated through a series of calibration processes, some faint transient signals of yet unexplained origin remain in the measurements. If they appear in the LISA data, these perturbations (also called glitches) could skew the characterization of gravitational-wave sources or even be confused with gravitational-wave bursts. For the first time, we provide a comprehensive census of LPF transient events. Our analysis is based on a phenomenological shapelet model allowing us to derive simple statistics about the physical features of the glitch population. We then implement a generator of synthetic glitches designed to be used for subsequent LISA studies, and perform a preliminary evaluation of the effect of the glitches on future LISA data analyses.
G359.13142-0.20005: A steep spectrum radio pulsar candidate with an X-ray counterpart running into the Galactic Center Snake (G359.1-0.2)
(Oxford University Press, 2024-02-24) Yusef-Zadeh, F.; Zhao, Jun-Hui; Arendt, Richard; Wardle, M.; Heinke, C. O.; Royster, M.; Lang, C.; Michail, J.
The Snake is a remarkable Galactic center radio filament with a morphology characterized by two kinks along its ~20’ extent. The major and minor kinks are located where the filament is most distorted from a linear magnetized structure running perpendicular to the Galactic plane. We present Chandra, VLA, and MeerKAT data and report the detection of an X-ray and radio source at the location of the major kink. High-resolution radio images of the major kink reveal a compact source with a steep spectrum with spectral index α ∼ −2.7 surrounded by extended emission. The radio luminosity and steep spectrum of the compact source are consistent with a pulsar. We also show flattening of the spectrum and enhanced synchrotron emissivity away from the position of the major kink along the Snake, which suggests injection of relativistic particles along the Snake. We argue that the major kink is created by a fast-moving (~500–1000 km s⁻¹), object punching into the Snake, distorting its magnetic structure, and producing X-ray emission. X-ray emission pinpoints an active acceleration site where the interaction is taking place. A secondary kink is argued to be induced by the impact of the high-velocity object producing the major kink.

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