Engineering topics

Del Monte, Ettore

Publications and source records attributed to Del Monte, Ettore.

6 records

DOE OSTI2022

Polarized blazar X-rays imply particle acceleration in shocks

Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization—the only range available until now—probe extended regions of the jet containing particles that left the acceleration site days to years earlier and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree Π X of around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

A Weighted Analysis to Improve the X-Ray Polarization Sensitivity of the Imaging X-ray Polarimetry Explorer

Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer mission that was launched at the end of 2021 to measure the polarization of X-ray emission from tens of astronomical sources. Its focal-plane detectors are based on the Gas Pixel Detector, which measures the polarization by imaging photoelectron tracks in a gas mixture and reconstructing their initial directions. The quality of the single track, and then the capability of correctly determining the original direction of the photoelectron, depends on many factors, e.g., whether the photoelectron is emitted at low or high inclination with respect to the collection plane or the occurrence of a large Coulomb scattering close to the generation point. The reconstruction algorithm used by IXPE to obtain the photoelectron emission direction also calculates several properties of the shape of the tracks that characterize the process. In this paper we compare several such properties and identify the best one to weight each track on the basis of the reconstruction accuracy. We demonstrate that significant improvement in sensitivity can be achieved with this approach and for this reason it will be the baseline for IXPE data analysis.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2020

IXPE Mission System Concept and Development Status

The Goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mi SMEX), is to expand understanding of high-energy astrophysical processes and sources, in support of NASA’s first science objective in Astrophysics: “Discover how the universe works.” IXPE, an international collaboration, will conduct X-ray imaging polarimetry for multiple categories of cosmic X-ray sources such as neutron stars, stellar-mass black holes, supernova remnants and active galactic nuclei. The Observatory uses a single science operational mode capturing the X-ray data from the targets. The IXPE Observatory consists of spacecraft and payload modules built up in parallel to form the Observatory during system integration and test. The payload includes three X-ray telescopes each consisting of a polarization-sensitive, gas pixel X-ray detector, paired with its corresponding grazing incidence mirror module assembly (MMA). A deployable boom provides the correct separation (focal length) between the detector units (DU) and MMAs. These payload elements are supported by the IXPE spacecraft which is derived from the BCP-small spacecraft architecture. This paper summarizes the IXPE mission science objectives, updates the Observatory implementation concept including the payload and spacecraft ts and summarizes the mission status since last year’s conference.

Deininger, William D.↗

NASA NTRS2019

The Imaging X-Ray Polarimetry Explorer (IXPE): Technical Overview II

The Imaging X-ray Polarimetry Explorer (IXPE) will add polarization to the properties (time, energy, and position) observed in x-ray astronomy. A NASA Astrophysics Small Explorer (SMEX) in partnership with the Italian Space Agency (ASI), IXPE will measure the 2–8-keV polarization of a few dozen sources during the first 2 years following its 2021 launch. The IXPE Observatory includes three identical x-ray telescopes, each comprising a 4-m-focal-length (grazingincidence) mirror module assembly (MMA) and a polarization-sensitive (imaging) detector unit (DU), separated by a deployable optical bench. The Observatory’s Spacecraft provides typical subsystems (mechanical, structural, thermal, power, electrical, telecommunications, etc.), an attitude determination and control subsystem for 3-axis stabilized pointing, and a command and data handling subsystem communicating with the science instrument and the Spacecraft subsystems.

X-ray astronomy↗

NASA NTRS2018

Imaging X-Ray Polarimetry Explorer (IXPE) Risk Management

The Imaging X-ray Polarimetry Explorer (IXPE) project is an international collaboration to build and fly a polarization sensitive X-ray observatory. The IXPE Observatory consists of the spacecraft and payload. The payload is composed of three X-ray telescopes, each consisting of a mirror module optical assembly and a polarization-sensitive X-ray detector assembly; a deployable boom maintains the focal length between the optical assemblies and the detectors. The goal of the IXPE Mission is to provide new information about the origins of cosmic X-rays and their interactions with matter and gravity as they travel through space. IXPE will do this by exploiting its unique capability to measure the polarization of X-rays emitted by cosmic sources. The collaboration for IXPE involves national and international partners during design, fabrication, assembly, integration, test, and operations. The full collaboration includes NASA Marshall Space Flight Center (MSFC), Ball Aerospace, the Italian Space Agency (ASI), the Italian Institute of Astrophysics and Space Planetology (IAPS)/Italian National Institute of Astrophysics (INAF), the Italian National Institute for Nuclear Physics (INFN), the University of Colorado (CU) Laboratory for Atmospheric and Space Physics (LASP), Stanford University, McGill University, and the Massachusetts Institute of Technology. The goal of this paper is to discuss risk management as it applies to the IXPE project. The full IXPE Team participates in risk management providing both unique challenges and advantages for project risk management. Risk management is being employed in all phases of the IXPE Project, but is particularly important during planning and initial execution-the current phase of the IXPE Project. The discussion will address IXPE risk strategies and responsibilities, along with the IXPE management process which includes risk identification, risk assessment, risk response, and risk monitoring, control, and reporting.

IXPE↗

NASA NTRS2018

Imaging X-ray Polarimetry Explorer Mission Overview and Systems Engineering Status

The Imaging X-ray Polarimetry Explorer (IXPE) is a space-based observatory that will have the capability to measure the polarization of X-rays from astrophysical sources. IXPE will improve sensitivity over OSO-8, the only previous X-ray polarimeter, by two orders of magnitude in required exposure time. IXPE will yield insight into our understanding of X-ray production in objects such as neutron stars as well as stellar and supermassive black holes. IXPE measurements will provide new dimensions for probing a wide range of cosmic X-ray sources-including active galactic nuclei (AGN) and microquasars, pulsars and pulsar wind nebulae, magnetars, accreting X-ray binaries, supernova remnants, and the Galactic center.

Houston, Janice↗