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Michael J. Pivovaroff

Bio: Michael J. Pivovaroff is an academic researcher from Lawrence Livermore National Laboratory. The author has contributed to research in topics: Pulsar & Axion. The author has an hindex of 41, co-authored 127 publications receiving 9192 citations. Previous affiliations of Michael J. Pivovaroff include Massachusetts Institute of Technology & University of California, Berkeley.


Papers
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Journal ArticleDOI
Fiona A. Harrison1, William W. Craig2, William W. Craig3, Finn Erland Christensen4, Charles J. Hailey5, William W. Zhang6, Steven E. Boggs3, Daniel Stern1, W. Rick Cook1, Karl Forster1, Paolo Giommi, Brian W. Grefenstette1, Yunjin Kim1, Takao Kitaguchi7, Jason E. Koglin5, Kristin K. Madsen1, Peter H. Mao1, Hiromasa Miyasaka1, Kaya Mori5, M. Perri8, Michael J. Pivovaroff2, Simonetta Puccetti8, Vikram Rana1, Niels Jørgen Stenfeldt Westergaard4, J. L. Willis1, Andreas Zoglauer3, Hongjun An9, Matteo Bachetti10, Matteo Bachetti11, Nicolas M. Barrière3, Eric C. Bellm1, Varun Bhalerao1, Varun Bhalerao12, Nicolai Brejnholt4, Felix Fuerst1, Carl Christian Liebe1, Craig B. Markwardt6, Melania Nynka5, Julia Vogel2, Dominic J. Walton1, Daniel R. Wik6, David M. Alexander13, L. R. Cominsky14, Ann Hornschemeier6, Allan Hornstrup4, Victoria M. Kaspi9, Greg Madejski, Giorgio Matt15, S. Molendi7, David M. Smith16, John A. Tomsick3, Marco Ajello3, David R. Ballantyne17, Mislav Baloković1, Didier Barret10, Didier Barret11, Franz E. Bauer18, Roger Blandford8, W. Niel Brandt19, Laura Brenneman20, James Chiang8, Deepto Chakrabarty21, Jérôme Chenevez4, Andrea Comastri7, Francois Dufour9, Martin Elvis20, Andrew C. Fabian22, Duncan Farrah23, Chris L. Fryer24, Eric V. Gotthelf5, Jonathan E. Grindlay20, D. J. Helfand25, Roman Krivonos3, David L. Meier1, Jon M. Miller26, Lorenzo Natalucci7, Patrick Ogle1, Eran O. Ofek27, Andrew Ptak6, Stephen P. Reynolds28, Jane R. Rigby6, Gianpiero Tagliaferri7, Stephen E. Thorsett29, Ezequiel Treister30, C. Megan Urry31 
TL;DR: The Nuclear Spectroscopic Telescope Array (NuSTAR) as discussed by the authors is the first focusing high-energy X-ray telescope in orbit, which operates in the band from 3 to 79 keV.
Abstract: The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to the peak epoch of galaxy assembly in the universe (at z ≾ 2) by surveying selected regions of the sky; (2) study the population of hard X-ray-emitting compact objects in the Galaxy by mapping the central regions of the Milky Way; (3) study the non-thermal radiation in young supernova remnants, both the hard X-ray continuum and the emission from the radioactive element ^(44)Ti; (4) observe blazars contemporaneously with ground-based radio, optical, and TeV telescopes, as well as with Fermi and Swift, to constrain the structure of AGN jets; and (5) observe line and continuum emission from core-collapse supernovae in the Local Group, and from nearby Type Ia events, to constrain explosion models. During its baseline two-year mission, NuSTAR will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6° inclination orbit, the observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an expected orbit lifetime of 10 yr, we anticipate proposing a guest investigator program, to begin in late 2014.

1,966 citations

Journal ArticleDOI
TL;DR: The Nuclear Spectroscopic Telescope Array (NuSTAR) as discussed by the authors is the first focusing high-energy X-ray telescope in orbit, which operates in the band from 3 - 79 keV.
Abstract: The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 13 June 2012, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 -- 79 keV, extending the sensitivity of focusing far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low-background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than one-hundred-fold improvement in sensitivity over the collimated or coded-mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity, spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives, and will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6degree inclination orbit, the Observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an expected orbit lifetime of ten years, we anticipate proposing a guest investigator program, to begin in Fall 2014.

1,548 citations

Journal ArticleDOI
TL;DR: The axion-photon coupling strength of the CERN Axion Solar Telescope (CAST) was shown to be at least 0.02$ eV in the first vacuum phase (2003-2004) with low-background x-ray detectors and a new xray telescope as mentioned in this paper.
Abstract: During 2003--2015, the CERN Axion Solar Telescope (CAST) has searched for $a\to\gamma$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. In its final phase of solar axion searches (2013--2015), CAST has returned to evacuated magnet pipes, which is optimal for small axion masses. The absence of a significant signal above background provides a world leading limit of $g_{a\gamma} < 0.66 \times 10^{-10} {\rm GeV}^{-1}$ (95% C.L.) on the axion-photon coupling strength for $m_a \lesssim 0.02$ eV. Compared with the first vacuum phase (2003--2004), the sensitivity was vastly increased with low-background x-ray detectors and a new x-ray telescope. These innovations also serve as pathfinders for a possible next-generation axion helioscope.

752 citations

Posted Content
Yonit Hochberg1, Yonit Hochberg2, A. N. Villano3, Andrei Afanasev4  +238 moreInstitutions (98)
TL;DR: The white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.
Abstract: This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.

464 citations

31 Oct 2013
TL;DR: A review of the physics motivation for dark sectors and the exciting opportunities for experimental exploration is provided in this article, where axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles.
Abstract: Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and low-cost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere.

382 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: A binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors.
Abstract: On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

2,746 citations

Journal ArticleDOI
TL;DR: The Linac Coherent Light Source free-electron laser has achieved coherent X-ray generation down to a wavelength of 1.2 A and at a brightness that is nearly ten orders of magnitude higher than conventional synchrotrons.
Abstract: The Linac Coherent Light Source free-electron laser has now achieved coherent X-ray generation down to a wavelength of 1.2 A and at a brightness that is nearly ten orders of magnitude higher than conventional synchrotrons. Researchers detail the first operation and beam characteristics of the system, which give hope for imaging at atomic spatial and temporal scales.

2,648 citations

01 Jan 2005
TL;DR: The Monthly Notices as mentioned in this paper is one of the three largest general primary astronomical research publications in the world, published by the Royal Astronomical Society (RAE), and it is the most widely cited journal in astronomy.
Abstract: Monthly Notices is one of the three largest general primary astronomical research publications. It is an international journal, published by the Royal Astronomical Society. This article 1 describes its publication policy and practice.

2,091 citations