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1. The Imaging X-ray Polarimetry Explorer (IXPE)

Author

Martin C. Weisskopf, Brian Ramsey, Stephen L. O’Dell, Allyn Tennant, Ronald Elsner, Paolo Soffita, Ronaldo Bellazzini, Enrico Costa, Jeffery Kolodziejczak, Victoria Kaspi, Fabio Mulieri, Herman Marshall, Giorgio Matt, and Roger Romani

Subjects
Physics, QC1-999
Abstract

The Imaging X-ray Polarimetry Explorer (IXPE) expands observation space by simultaneously adding polarization to the array of X-ray source properties currently measured (energy, time, and location). IXPE will thus open new dimensions for understanding how X-ray emission is produced in astrophysical objects, especially in systems under extreme physical conditions. Keywords: X-ray astronomy, X-ray polarimetry, X-ray imaging

Published
2016
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3. X-ray Polarization Reveals the Precessions of the Neutron Star in Hercules X-1

Author

Jeremy Heyl, Victor Doroshenko, Denis González-Caniulef, Ilaria Caiazzo, Juri Poutanen, Alexander Mushtukov, Sergey Tsygankov, Demet Kirmizibayrak, Matteo Bachetti, George Pavlov, Iván Agudo, Lucio Antonelli, Luca Baldini, Wayne Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolo Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Michal Dovciak, Steven Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier Garcia, Shuichi Gunji, Wataru Iwakiri, Svetlana Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frederic Marin, Andrea Marinucci, Alan Marscher, Herman Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, C.-Y. Ng, Stephen O'Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, Abel Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian Ramsey, John Rankin, Ajay Ratheesh, Oliver Roberts, Roger Romani, Carmelo Sgro, Patrick Slane, Paolo Soffitta, Gloria Spandre, Doug Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn Tennant, Nicholas Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, Martin Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane

Abstract

In an X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the inner edge of the disc, funneling the gas to flow onto the magnetic poles on its surface. Hercules X-1 is in many ways the prototypical X-ray pulsar; it shows persistent X-ray emission and it resides with its companion HZ Her, a two-solar-mass star, at about 7~kpc from Earth1. Its emission varies on three distinct timescales2 the neutron star rotates every 1.2~seconds, it is eclipsed by its companion each 1.7~days, and the system exhibits a superorbital period of 35~days which has remained remarkably stable since its discovery3. Several lines of evidence point to the source of this variation as the precession of the accretion disc4,5, the precession of the neutron star6,7 or both8. Despite the many hints over the past fifty years, the precession of the neutron star itself has yet not been confirmed or refuted. We here present X-ray polarization measurements with the Imaging X-ray Polarimetry Explorer9 (IXPE) which probe the spin geometry of the neutron star. These observations provide direct evidence that the 35-day-period is set by the free precession of the neutron star crust, which has the important implication that its moment of inertia eigenvalues differ fractionally by a few parts per ten million10. Furthermore, we find indications that the basic spin geometry of the neutron star is altered by torques on timescale of a few hundred days.

Published
2023
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4. Arcus: The Soft X-ray Grating Explorer

Author

Randall K Smith, Margaret Abraham, Grace Baird, Marshall Bautz, Jay Bookbinder, Joel Bregman, Laura Brenneman, Nancy Brickhouse, David Burrows, Vadim Burwitz, Joseph Bushman, Claude Canizares, Deepto Chakrabarty, Peter Cheimets, Elisa Costantini, Simon Dawson, Casey DeRoo, Abraham Falcone, Adam Foster, Luigi Gallo, Catherine E Grant, H Moritz Gunther, Ralf K Heilmann, Butler Hine, David Huenemoerder, Steve Jara, Jelle Kaastra, Ingo Kreykenbohm, Kristin Madsen, Michael McDonald, Michael McEachen, Randall McEntaffer, Herman Marshall, Eric Miller, Jon Miller, Elisabeth Morse, Richard Mushotzky, Kirpal Nandra, Michael Nowak, Frits Paerels, Robert Petre, Katja Poppenhaeger, Andrew Ptak, Paul Reid, Karolyn S Ronzano, Jeremy Sanders, Mark Schattenburg, Jonathan Schonfeld, Norbert Schulz, Alan Smale, Pasquale Temi, Lynne Valencic, Stephen Walker, Richard Willingale, Joern Wilms, and Scott Wolk

Subjects
Optics
Abstract

Arcus provides high-resolution soft X-ray spectroscopy in the 12-50 Å bandpass with unprecedented sensitivity, including spectral resolution > 2500 and effective area > 250 cm2. The three top science goals for Arcus are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback, and (3) to explore how stars form and evolve. Arcus uses the same 12 m focal length grazing-incidence Silicon Pore X-ray Optics (SPOs) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. Combined with the high-heritage NGIS LEOStar-2 spacecraft and launched into 4:1 lunar resonant orbit, Arcus provides high sensitivity and high efficiency observing of a wide range of astrophysical sources.

Published
2019
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5. When the Milky Way hosted a quasar

Author

Frederic Marin, Eugene Churazov, Ildar Khabibullin, Riccardo Ferrazzoli, Laura Di Gesu, Thibault Barnouin, Alessandro Di Marco, Riccardo Middei, Alexey Vikhlinin, Enrico Costa, Paolo Soffitta, Fabio Muleri, Rashid Sunyaev, William Forman, Ralph Kraft, Stefano Bianchi, Immacolata Donnarumma, Pierre-Olivier Petrucci, Teruaki Enoto, Iván Agudo, Lucio Antonelli, Matteo Bachetti, Luca Baldini, Wayne Baumgartner, Ronaldo Bellazzini, Stephen Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolo Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Niccolo Di Lalla, Victor Doroshenko, Michal Dovciak, Steven Ehlert, Yuri Evangelista, Sergio Fabiani, Javier Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Adam Ingram, Wataru Iwakiri, Svetlana Jorstad, Philip Kaaret, Vladimir Karas, Takao Kitaguchi, Jeffery Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Andrea Marinucci, Alan Marscher, Herman Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, C.-Y. Ng, Stephen O'Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George Pavlov, Abel Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian Ramsey, John Rankin, Ajay Ratheesh, Oliver Roberts, Roger Romani, Carmelo Sgro, Patrick Slane, Gloria Spandre, Doug Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn Tennant, Nicholas Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Martin Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane

Abstract

The Galactic Center harbors diffuse X-ray emission co-spatial with giant molecular clouds and featuring hard X-ray spectra with a prominent fluorescent iron line at 6.4 keV [1–3]. These spectral properties are characteristic of the reflected emission from a neutral gas illuminated by X-rays. However, there are no persistent X-ray sources in that region that are bright enough to provide the required illumination level. Moreover, the observed diffuse emission is variable on time scales of years [4, 5], implying that the primary source of X-rays must be variable, too. The most exciting and far-reaching scenario is that a very powerful flare from the central supermassive black hole of the Milky Way, Sgr A*, provided the required flux of X-ray photons, when for a period shorter than a few years it became at least five orders of magnitude brighter than is typically observed today. Even if the primary emission was unpolarized, the reflected emission should be polarized in the direction perpendicular to the scattering plane with the degree of polarization being set by the scattering angle. Therefore, by measuring X-ray polarization one can infer the direction towards the primary source and, simultaneously, the mutual positions in space of the source and the cloud [6]. Here, we report the detection of X-ray polarization from the Galactic Center region obtained by the recently launched Imaging X-ray Polarimetry Explorer (IXPE) mission. For a large region where Chandra and XMM-Newton identify spectral signatures of the reflection, IXPE measures a polarization degree of 31% ± 11% with a polarization angle -48° ± 11° for the scattered continuum. The latter corroborates the conjecture that Sgr A* is the primary source of illuminating photons, while the former implies that some 200 years ago our Galactic Center hosted an extremely bright active galactic nucleus, on par with the ones found in Seyfert galaxies, though only for a short time.

Published
2022
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6. Arcus: exploring the formation and evolution of clusters, galaxies, and stars

Author

Randall K. Smith, Marshall Bautz, Joel Bregman, Laura Brenneman, Nancy Brickhouse, Esra Bulbul, Vadim Burwitz, Joseph Bushman, Claude Canizares, Deepto Chakrabarty, Peter Cheimets, Elisa Costantini, Casey DeRoo, Abe Falcone, Adam Foster, Luigi Gallo, Catherine Grant, Hans Guenther, Ralf Heilmann, Sarah Heine, Butler Hine, David Huenemoerder, Steve Jara, Jelle Kaastra, Erin Kara, Ingo Kreykenbohm, Kristin Madsen, Herman Marshall, Michael McDonald, Randall McEntaffer, Jon Miller, Eric Miller, Richard Mushotzky, Kirpal Nandra, Michael Nowak, Frederik Paerels, Robert Petre, Katja Poppenhaeger, Andrew Ptak, Paul Reid, Karolyn Ronzano, Agata Rozanska, Jenna Samra, Jeremy Sanders, Mark Schattenburg, Jonathan Schonfeld, Norbert Schulz, Alan Smale, Pasquale Temi, Lynne Valencic, Stephen Walker, Joern Wilms, and Scott Wolk

Published
2022
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8. Angling for X-ray pulsar geometry with polarimetry

Author

Victor Doroshenko, Juri Poutanen, Sergey Tsygankov, Valery Suleimanov, Matteo Bachetti, Ilaria Caiazzo, Enrico Costa, Alessandro Di Marco, Jeremy Heyl, Fabio La Monaca, Fabio Muleri, Alexander Mushtukov, George Pavlov, Brian Ramsey, John Rankin, Andrea Santangelo, Paolo Soffitta, Ruediger Staubert, Martin Weisskopf, Silvia Zane, Iván Agudo, Lucio Antonelli, Luca Baldini, Wayne Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen Bongiorno, Raffaella Bonino, Niccolò Bucciantini, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Michal Dovciak, Steven Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana Jorstad, Vladimir Karas, Takao Kitaguchi, Jeffery Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan Marscher, Herman Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, C.-Y. Ng, Stephen O'Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, Abel Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Ajay Ratheesh, Roger Romani, Carmelo Sgro, Patrick Slane, Gloria Spandre, Rashid Sunyaev, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn Tennant, Nicolas Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, Kinwah Wu, and Fei Xie

Abstract

Using observations of X-ray pulsar Her X-1 by the Imaging X-ray Polarimetry Explorer, we report on a highly significant detection of the polarization signal from an accreting neutron star. The observed degree of the linear polarization of ∼ 10% is found to be far below theoretical expectations for this object, and stays low throughout the spin cycle of the pulsar. Both the polarization degree and the angle exhibit variability with pulse phase, which allowed us to measure the pulsar spin position angle and magnetic obliquity of the neutron star, which is an essential step towards detailed modeling of the intrinsic emission of X-ray pulsars. Combining our results with the optical polarimetric data, we find that the spin axis of the neutron star and the angular momentum of the binary orbit are misaligned by at least ∼20 deg, which is a strong argument in support of the models explaining stability of the observed super-orbital variability with the precession of the neutron star.

Published
2022
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9. NuSTAR reveals the hidden nature of SS433

Author

S. E. Boggs, Dominic J. Walton, M. Brightman, Matthew J. Middleton, Thomas Dauser, S. Eikenberry, Brian W. Grefenstette, Fiona A. Harrison, Diego Altamirano, Daniel Stern, A. J. Bird, Felix Fuerst, K. Forster, Gilad Perez, K. Madsen, William W. Craig, James Miller-Jones, Michael Parker, C. Hailey, William W. Zhang, William Alston, Herman Marshall, Y-F. Jiang, Ciro Pinto, Matteo Bachetti, Philip A. Charles, Andrew C. Fabian, Finn Erland Christensen, and ITA

Subjects
Accretion, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Luminosity, binaries [Accretion discs – X-rays], 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, geography, geography.geographical_feature_category, Accretion (meteorology), 010308 nuclear & particles physics, Astronomy and Astrophysics, Quasar, Numerical models, Redshift, Erg (landform), Space and Planetary Science, Precession, Outflow, Astrophysics - High Energy Astrophysical Phenomena
Abstract

SS433 is the only Galactic binary system known to persistently accrete at highly super-critical (or hyper-critical) rates, similar to those in tidal disruption events, and likely needed to explain the rapid growth of those very high redshift quasars containing massive SMBHs. Probing the inner regions of SS433 in the X-rays is crucial to understanding this system, and super-critical accretion in general, but is highly challenging due to obscuration by the surrounding wind, driven from the accretion flow. NuSTAR observed SS433 in the hard X-ray band across multiple phases of its 162 day super-orbital precession period. Spectral-timing tools allow us to infer that the hard X-ray emission from the inner regions is likely being scattered towards us by the walls of the wind-cone. By comparing to numerical models, we determine an intrinsic X-ray luminosity of $\ge$ 2$\times$10$^{37}$ erg/s and that, if viewed face on, we would infer an apparent luminosity of $>$ 1$\times$10$^{39}$ erg/s, confirming SS433's long-suspected nature as an ultraluminous X-ray source (ULX). We present the discovery of a narrow, $\sim 100$s lag due to atomic processes occurring in outflowing material travelling at least 0.14-0.29c, which matches absorption lines seen in ULXs and -- in the future -- will allow us to map a super-critical outflow for the first time., 14 pages, 10 figures, accepted for publication in MNRAS

Published
2021
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12. Modeling contamination migration on the Chandra X-ray Observatory IV

Author

Matthew T. Dahmer, Allyn F. Tennant, Catherine E. Grant, Akos Bogdan, Herman . Marshall, Paul P. Plucinsky, Neil W. Tice, Douglas A. Swartz, and Stephen L. O'Dell

Subjects
0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, 02 engineering and technology, 010303 astronomy & astrophysics, 01 natural sciences
Published
2017
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15. Designing, constructing, and testing an X-ray polarimeter

Author

Herman Marshall., Massachusetts Institute of Technology. Dept. of Mechanical Engineering., Jenks, Kevin P. (Kevin Patrick), Herman Marshall., Massachusetts Institute of Technology. Dept. of Mechanical Engineering., and Jenks, Kevin P. (Kevin Patrick)

Abstract

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011., Cataloged from PDF version of thesis., Includes bibliographical references (p. 24)., X-ray astronomy has been an important field since its birth 50 years ago. However, Xray polarization measurements have been almost non-existent, especially when compared to the amount of polarimetry being performed in the other bands of the spectrum. One method of filtering a specific energy of polarized X-rays involves reflecting these X-rays off of a correctly tuned multilayer mirror at a specific grazing angle. A design for a small spacecraft incorporating this type of instrument has been proposed, but the effectiveness of using multilayer mirrors as polarization filters has never been tested in a laboratory setting. A design for using an existing X-ray beamline as a means of testing this method was developed. The necessary modifications to both the source and detector end were made, but due to an inability to completely eliminate small misalignments in the system, the full tests of the multilayer mirrors could not be performed. Further research could be performed to identify and correct the cause of the misalignments and continue the evaluation of the multilayer mirrors as a polarimeter., by Kevin P. Jenks., S.B.

Published
2012

16. SYSTEMATIC UNCERTAINTIES IN THE SPECTROSCOPIC MEASUREMENTS OF NEUTRON STAR MASSES AND RADII FROM THERMONUCLEAR X-RAY BURSTS. III. ABSOLUTE FLUX CALIBRATION.

Author

Tolga Güver, Feryal Özel, Herman Marshall, Dimitrios Psaltis, Matteo Guainazzi, and Maria Díaz-Trigo

Subjects
NEUTRON stars, X-ray bursts, NUCLEAR size (Physics), EQUATIONS of state, TIME-resolved spectroscopy
Abstract

Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826–238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE/PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0 ± 0.3% less flux than the RXTE/PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared with EPIC MOS1, MOS2, and ACIS-S detectors. We also show that any intrinsic time-dependent systematic uncertainty that may exist in the calibration of the satellites has already been implicity taken into account in the neutron star radius measurements. [ABSTRACT FROM AUTHOR]

Published
2016
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17. Which Shakespeare character would you most like to play?

Author

Herman, Marshall

Subjects
CHARACTERS of William Shakespeare, DRAMATIC works of William Shakespeare
Abstract

The article reveals the roles some celebrities would like to portray in Shakespeare's plays when asked at the Public Theater's summer gala in Manhattan, New York.

Published
2009

18. What's your idea of heaven?

Author

Herman, Marshall

Subjects
CELEBRITIES, FUNDRAISING
Abstract

This article reports on celebrities at the 2009 Art of Elysium Heaven & Hell charity benefit.

Published
2009

19. What's your art fantasy?

Author

Herman, Marshall

Subjects
CHARITIES, CELEBRITIES
Abstract

Photographs are presented of celebrities in attendance at the 2008 Gala in the Garden charity event at the Hammer Museum in Los Angeles, California, including actor Tobey Maguire with wife Jennifer Meyer, model Linda Evangelista, and actor Ben Stiller.

Published
2008

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