Astronomical Informant

2022-06-17 04:36:30 arXiv:Cosmic (hydrogen) reionization marks one of the major phase transitions of the universe at redshift z >= 6. During this epoch, hydrogen atoms in the intergalactic medium (IGM) were ionized by Lyman continuum (LyC) photons. However, it remains challenging to identify the major sources of the LyC photons responsible for reionization. In particular, individual contributions of quasars (or active galactic nuclei, AGNs) and galaxies are still under debate. Here we construct the far-ultraviolet (far-UV) luminosity function for type 1 quasars at z >= 6 that spans 10 magnitudes (-19 < M_UV < -29), conclusively showing that quasars made a negligible contribution to reionization. We mainly search for quasars in the low-luminosity range of M_UV > -23 mag that is critical to determine quasars' total LyC photon production but has been barely explored previously. We find that the quasar population can only provide less than 7% (95% confidence level) of the total photons needed to keep the universe ionized at z = 6.0 - 6.6. Our result suggests that galaxies, presumably low-luminosity star-forming systems, are the major sources of hydrogen reionization.

via astro-ph updates on arXiv.org https://ift.tt/XwPmLyO Aprire / Come

2022-06-11 01:29:47 NASA to Discuss, Conduct Test to Prepare for Artemis I Moon Mission
http://www.nasa.gov/press-release/nasa-to-discuss-conduct-test-to-prepare-for-artemis-i-moon-mission

NASA is targeting Saturday, June 18, for the beginning of the next wet dress rehearsal test of the agency’s Space Launch System (SLS) rocket and Orion spacecraft at the Kennedy Space Center in Florida with tanking operations on Monday, June 20. Aprire / Come

2022-06-10 19:55:47 NASA Student Business Competition Gets Boost by White House Initiative
http://www.nasa.gov/press-release/nasa-student-business-competition-gets-boost-by-white-house-initiative

NASA’s Minority University Education and Research Program (MUREP) Innovation and Tech Transfer Idea Competition (MITTIC), a Shark Tank-style competition for students at minority-serving institutions, is officially included in the 2022 historically Black colleges and universities (HBCU) Scholar Recognition Program. Aprire / Come

2022-06-10 19:02:21 NASA Student Business Competition Gets Boost by White House Initiative
http://www.nasa.gov/press-release/nasa-student-business-competition-gets-boost-by-white-house-initiative

NASA’s Minority University Education and Research Program (MUREP) Innovation and Tech Transfer Idea Competition (MITTIC), a Shark Tank-style competition for students at minority-serving institutions, is officially included in the 2022 historically Black colleges and universities (HBCU) Scholar Recognition Program. Aprire / Come

2022-06-10 17:36:01 Hubble Investigates an Enigmatic Star Cluster
http://www.nasa.gov/image-feature/goddard/2022/hubble-investigates-an-enigmatic-star-cluster

Unlike most globular clusters, Ruprecht 106 may be what astronomers call a single population globular cluster. Aprire / Come

2022-06-10 10:01:32 ATel 15430: Erratum to Atel #15429
https://www.astronomerstelegram.org/?read=15430

... Aprire / Come

2022-06-10 10:00:39 ATel 15429: NuSTAR observations reveal relativistic reflection and strong absorption features in the spectrum of 1A 1744-361
https://www.astronomerstelegram.org/?read=15429

We present preliminary spectral results from NuSTAR observations (OBSID 90801312001) of the accreting neutron star 1A 1744-361 in outburst (Atels #15407, #15408, #15410, #15424). ... Aprire / Come

2022-06-10 05:36:34 arXiv:In both particle physics and muon applications, a high-resolution muon momentum measurement capability plays a significant role not only in providing valuable information on the properties of subatomic particles but also in improving the utilizability of cosmic ray muons. Typically, muon momentum is measured by reconstructing a curved muon path using a strong magnetic field and muon trackers. Alternatively, a time-of-flight and Cherenkov ring imager are less frequently applied, especially when there is a need to avoid a magnetic field. However, measurement resolution is much less than that of magnetic spectrometers, approximately 20% whereas it is nearly 4% or less when using magnets and trackers. Here, we propose a different paradigm to estimate muon momentum that utilizes multiple pressurized gas Cherenkov radiators. Using the fact that the refractive index of gas medium varies depending on its pressure and temperature, we can optimize the muon Cherenkov threshold momentum levels for which a muon signal will be detected. In this work, we demonstrate that muon momentum can be estimated with mean resolution of {sigma_p}/p < 20% and mean classification rate of 90.08% in the momentum range of 0.1 to 10.0 GeV/c by analyzing optical photon signals from each Cherenkov radiator. We anticipate our new spectrometer will significantly improve quality of imaging and reduce scanning time in cosmic ray muon applications by being incorporated with existing instruments.

via astro-ph updates on arXiv.org https://ift.tt/3UQGV5q Aprire / Come

2022-06-10 05:36:33 arXiv:The memo describes the methods used to track the long-term gain variations in the NuSTAR detectors. It builds on the analysis presented in Madsen et al. (2015) using the deployable calibration source to measure the gain drift in the NuSTAR CdZnTe detectors. This is intended to be a live document that is periodically updated as new entries are required in the NuSTAR gain CALDB files. This document covers analysis up through early-2022 and the gain v010 CALDB file released in version 20220510.

via astro-ph updates on arXiv.org https://ift.tt/wYgFEeA Aprire / Come

2022-06-10 05:36:31 arXiv:The outer parts of the Milky Way's disc are significantly out of equilibrium. Using only distances and proper motions of stars from Gaia's Early Data Release 3, in the range |b|<10{\deg}, 130{\deg}
via astro-ph updates on arXiv.org https://ift.tt/BLRTu2E

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