Brian D. Ramsey
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View article: Hybrid-integrated InGaAs/InP SPAD arrays for quantum communications
Hybrid-integrated InGaAs/InP SPAD arrays for quantum communications Open
Photonic integration is a promising route to miniaturise the hardware of quantum key distribution (QKD), yet the monolithic integration of single-photon detectors remains a significant challenge. QKD receiver chips integrating superconduct…
View article: In-flight Performance of the IXPE Telescopes
In-flight Performance of the IXPE Telescopes Open
We present a comprehensive characterization of the on-orbit imaging performance of the three telescopes on board the Imaging X-ray Polarimetry Explorer (IXPE). Each telescope comprises a Wolter-I mirror module assembly and a Gas Pixel Dete…
View article: In-flight performance of the IXPE telescopes
In-flight performance of the IXPE telescopes Open
We present a comprehensive characterization of the on-orbit imaging performance of the three telescopes on board the Imaging X-ray Polarimetry Explorer (IXPE). Each telescope comprises a Wolter-I mirror module assembly and a Gas Pixel Dete…
View article: X-Ray Polarization Detection of the Pulsar Wind Nebula in G21.5–0.9 with IXPE
X-Ray Polarization Detection of the Pulsar Wind Nebula in G21.5–0.9 with IXPE Open
We present the X-ray polarization observation of G21.5−0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in 2023 October, with a total livetime of approximately 837 ks. Using differ…
View article: The Telescope Calibration of the Imaging X-Ray Polarimetry Explorer
The Telescope Calibration of the Imaging X-Ray Polarimetry Explorer Open
Fifty years after the very first sounding rocket measurement of cosmic X-ray polarization, the Imaging X-ray Polarimetry Explorer (IXPE) mission has effectively opened a new window into the X-ray sky. Prior to launch of IXPE, an extensive …
View article: Inflight calibration of SRG/ART-XC point spread function at large off-axis angles
Inflight calibration of SRG/ART-XC point spread function at large off-axis angles Open
The knowledge of the point spread function (PSF) of the Mikhail Pavlinsky Astronomical Roentgen Telescope - X-ray Concentrator (ART-XC) telescope aboard the Spectrum-Roentgen-Gamma (SRG) observatory plays an especially crucial role in the …
View article: The Telescope Calibration of the Imaging X-ray Polarimetry Explorer
The Telescope Calibration of the Imaging X-ray Polarimetry Explorer Open
Fifty years after the very first sounding rocket measurement of cosmic X-ray polarization, the Imaging X-ray Polarimetry Explorer (IXPE) mission has effectively opened a new window into the X-ray sky. Prior to launch of IXPE, an extensive …
View article: Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry
Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry Open
Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray …
View article: Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry
Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry Open
Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray …
View article: Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations
Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations Open
We present Crab X-ray polarization measurements using Imaging X-Ray Polarimetry Explorer (IXPE) data with a total exposure of 300 ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more puls…
View article: Probing the polarized emission from SMC X-1: The brightest X-ray pulsar observed by IXPE
Probing the polarized emission from SMC X-1: The brightest X-ray pulsar observed by IXPE Open
Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry…
View article: Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry
Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry Open
Discovery of pulsations from a number of ultra-luminous X-ray (ULX) sources proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve…
View article: The imaging x-ray polarimetry explorer 2.5 years later
The imaging x-ray polarimetry explorer 2.5 years later Open
Soffitta, Paolo et al.-- Full list of the authors: Soffitta, Paolo; Baldini, Luca; Baumgartner, Wayne; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bucciantini, Niccolò; Costa, Enrico; Dovčiak, Michal; Ehlert, Steven; Kaaret, Philip E.; Kol…
View article: Considerations on Possible Directions for a Wide Band Polarimetry X-ray Mission
Considerations on Possible Directions for a Wide Band Polarimetry X-ray Mission Open
The Imaging X-ray Polarimetry Explorer (IXPE) has confirmed that X-ray polarimetry is a valuable tool in astronomy, providing critical insights into the emission processes and the geometry of compact objects. IXPE was designed to be sensit…
View article: Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1
Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1 Open
Weakly magnetized neutron stars in X-ray binaries show a complex phenomenology with several spectral components that can be associated with the accretion disk, the boundary, and/or a spreading layer, a corona, and a wind. Spectroscopic inf…
View article: Analysis of Crab X-ray Polarization using Deeper IXPE Observations
Analysis of Crab X-ray Polarization using Deeper IXPE Observations Open
We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped $…
View article: Optimizing the electroforming process for full-shell X-ray optics
Optimizing the electroforming process for full-shell X-ray optics Open
Electroforming replication technology at the Marshall Space Flight Center has a long heritage of producing high-quality, full-shell X-ray mirrors for various applications. Nickel alloys are electroformed onto a super-polished mandrel in th…
View article: On the Making of IXPE
On the Making of IXPE Open
Drs. Weisskopf and Ramsey were the original Principal and Deputy Principal Investigators of the Imaging X-ray Polarimetry Explorer (IXPE). They outline the path to the development of IXPE and discuss the technical and programmatic history …
View article: Probing the polarized emission from SMC X-1: the brightest X-ray pulsar observed by IXPE
Probing the polarized emission from SMC X-1: the brightest X-ray pulsar observed by IXPE Open
Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry…
View article: Discovery of a Shock-compressed Magnetic Field in the Northwestern Rim of the Young Supernova Remnant RX J1713.7–3946 with X-Ray Polarimetry
Discovery of a Shock-compressed Magnetic Field in the Northwestern Rim of the Young Supernova Remnant RX J1713.7–3946 with X-Ray Polarimetry Open
Supernova remnants (SNRs) provide insights into cosmic-ray acceleration and magnetic field dynamics at shock fronts. Recent X-ray polarimetric measurements by the Imaging X-ray Polarimetry Explorer (IXPE) have revealed radial magnetic fiel…
View article: X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei: NGC 1068
X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei: NGC 1068 Open
Context. NGC 1068 is the most observed radio-quiet active galactic nucleus (AGN) in polarimetry, yet its high-energy polarization has never been probed before due to a lack of dedicated polarimeters. Aims. Using the first X-ray polarimeter…
View article: Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry
Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry Open
Discovery of pulsations from a number of ULXs proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as wel…
View article: Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13–0.11
Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13–0.11 Open
We report the discovery of X-ray polarization from the X-ray-bright filament G0.13−0.11 in the Galactic center (GC) region. This filament features a bright, hard X-ray source that is most plausibly a pulsar wind nebula (PWN) and an extende…
View article: X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068
X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068 Open
We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra…
View article: X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630–47 Challenges the Standard Thin Accretion Disk Scenario
X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630–47 Challenges the Standard Thin Accretion Disk Scenario Open
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 ≈50 σ confidenc…
View article: X-Ray Polarimetry of the Dipping Accreting Neutron Star 4U 1624–49
X-Ray Polarimetry of the Dipping Accreting Neutron Star 4U 1624–49 Open
We present the first X-ray polarimetric study of the dipping accreting neutron star 4U 1624−49 with the Imaging X-ray Polarimetry Explorer. We report a detection of polarization in the nondip time intervals with a confidence level of 99.99…
View article: First detection of polarization in X-rays for PSR B0540-69 and its nebula
First detection of polarization in X-rays for PSR B0540-69 and its nebula Open
We report on X-ray polarization measurements of the extra-galactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud (LMC), using a ~850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is …
View article: First Detection of Polarization in X-Rays for PSR B0540-69 and Its Nebula
First Detection of Polarization in X-Rays for PSR B0540-69 and Its Nebula Open
We report on X-ray polarization measurements of the extragalactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud, using a ∼850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresol…
View article: IXPE observation confirms a high spin in the accreting black hole 4U 1957+115
IXPE observation confirms a high spin in the accreting black hole 4U 1957+115 Open
We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The binary system has been in a high-soft spectral state since …