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Corentin Cadiou
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Daily Astro papers on the arXiv in all categories.

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    3UCubed: The IMAP Student Collaboration CubeSat Project

    3UCubed: The IMAP Student Collaboration CubeSat Project by Marcus Alfred et al. on Wednesday 30 November The 3UCubed project is a 3U CubeSat being jointly developed by the University of New Hampshire, Sonoma State University, and Howard University as a part of the NASA Interstellar Mapping and Acceleration Probe, IMAP, student collaboration. This project comprises of a multidisciplinary team of undergraduate students from all three universities. The mission goal of the 3UCubed is to understand how Earths polar upper atmosphere the thermosphere in Earths auroral regions, responds to particle precipitation and solar wind forcing, and internal magnetospheric processes. 3UCubed includes two instruments with rocket heritage to achieve the science mission: an ultraviolet photomultiplier tube, UVPMT, and an electron retarding potential analyzer ERPA. The spacecraft bus consists of the following subsystems: Attitude Determination and Control, Command and Data Handling, Power, Communication, Structural, and Thermal. Currently, the project is in the post-PDR stage, starting to build and test engineering models to develop a FlatSat prior to critical design review in 2023. The goal is to launch at least one 3U CubeSat to collect science data close to the anticipated peak of Solar Cycle 25 around July 2025. Our mother mission, IMAP, is also projected to launch in 2025, which will let us jointly analyze the science data of the main mission, providing the solar wind measurements and inputs to the magnetosphere with that of 3UCubed, providing the response of Earths cusp to these inputs. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.15781v1

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  2. ٣٠‏/١١‏/٢٠٢٢

    A Bayesian approach for torque modelling of BeXRB pulsars with application to super-Eddington accretors

    A Bayesian approach for torque modelling of BeXRB pulsars with application to super-Eddington accretors by A. S. Karaferias et al. on Wednesday 30 November In this study we present a method to estimate posterior distributions for standard accretion torque model parameters and binary orbital parameters for X-ray binaries using a nested sampling algorithm for Bayesian Parameter Estimation. We study the spin evolution of two Be X-ray binary systems in the Magellanic Clouds, RX J0520.5-6932 and RX J0209-7427, during major outbursts, in which they surpassed the Eddington-limit. Moreover, we apply our method to the recently discovered Swift J0243.6+6124; the only known Galactic pulsating ultra-luminous X-ray source. This is an excellent candidate for studying the disc evolution at super-Eddington accretion rates, for its luminosity span several orders of magnitude during its outburst, with a maximum $L_{\rm X}$ that exceeded the Eddington limit by a factor of $\sim 10$. Our method, when applied to RX J0520.5-6932 and RX J0209-7427, is able to identify the more favourable torque model for each system, while yielding meaningful ranges for the NS and orbital parameters. Our analysis for Swift J0243.6+6124 illustrates that, contrary to the standard torque model predictions, the magnetospheric radius and the Alfv\'en radius are not proportional to each other when surpassing the Eddington limit. Reported distance estimates of this source range between 5 and 7 kpc. Smaller distances require non-typical neutron star properties (i.e. mass and radius) and possibly lower radiative efficiency of the accretion column. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16079v1

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  3. ٣٠‏/١١‏/٢٠٢٢

    A Bayesian approach to RFI mitigation

    A Bayesian approach to RFI mitigation by S. A. K. Leeney et al. on Wednesday 30 November Radio Frequency Interference (RFI) is an endemic problem in radio astronomy. Information in contaminated frequency channels is lost and it can lead to significant systematic error if not properly modelled. In this paper we propose a RFI mitigation methodology that takes a Bayesian approach, where contaminated data is both flagged and managed as part of a single step fitting process. To the authors knowledge, our approach is first-of-its-kind. We provide a proof-of-concept of our methods which are also tested and shown to be effective on both a simple toy model and when incorporated into the Bayesian data analysis pipeline for REACH (a modern cosmological radio experiment). arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.15448v1

    ٢٥ من الثواني

  4. ٣٠‏/١١‏/٢٠٢٢

    A Catalog of the Highest-Energy Cosmic Rays Recorded During Phase I of Operation of the Pierre Auger Observatory

    A Catalog of the Highest-Energy Cosmic Rays Recorded During Phase I of Operation of the Pierre Auger Observatory by The Pierre Auger Collaboration et al. on Wednesday 30 November A catalog containing details of the highest-energy cosmic rays recorded through the detection of extensive air-showers at the Pierre Auger Observatory is presented with the aim of opening the data to detailed examination. Descriptions of the 100 showers created by the highest-energy particles recorded between 1 January 2004 and 31 December 2020 are given for cosmic rays that have energies in the range 78 EeV to 166 EeV. Details are also given of a further nine very-energetic events that have been used in the calibration procedure adopted to determine the energy of each primary. A sky plot of the arrival directions of the most energetic particles is shown. No interpretations of the data are offered. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16020v1

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  5. ٣٠‏/١١‏/٢٠٢٢

    A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane

    A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane by Felix J. Lockman et al. on Wednesday 30 November We have identified a new structure in the Milky Way: a leading component of the Smith high velocity cloud that is now crossing the Galactic plane near longitude 25 degrees. Using new 21cm HI data from the Green Bank Telescope (GBT) we measured the properties of several dozen clouds that are part of this structure. Their kinematics is consistent with that of the Smith Cloud with a VLSR exceeding that permitted by circular rotation in their direction. Most of the clouds in the Leading Component show evidence that they are interacting with disk gas allowing the location of the interaction to be estimated. The Leading Component crosses the Galactic plane at a distance from the Sun of 9.5 kpc, about 4.5 kpc from the Galactic Center. Its HI mass may be as high as 10^6 Solar masses, comparable to the mass of the neutral component of the Smith Cloud, but only a fraction of this is contained in clouds that are resolved in the GBT data. Like the Smith Cloud, the Leading Component appears to be adding mass and angular momentum to the ISM in the inner Galaxy. We suggest that the Smith Cloud is not an isolated object, but rather part of a structure that stretches more than 40 degrees (about 7 kpc) across the sky, in two pieces separated by a gap of about 1 kpc. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16598v1

    ١ من الدقائق

  6. ٣٠‏/١١‏/٢٠٢٢

    A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane

    A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane by Felix J. Lockman et al. on Wednesday 30 November We have identified a new structure in the Milky Way: a leading component of the Smith high velocity cloud that is now crossing the Galactic plane near longitude 25 degrees. Using new 21cm HI data from the Green Bank Telescope (GBT) we measured the properties of several dozen clouds that are part of this structure. Their kinematics is consistent with that of the Smith Cloud with a VLSR exceeding that permitted by circular rotation in their direction. Most of the clouds in the Leading Component show evidence that they are interacting with disk gas allowing the location of the interaction to be estimated. The Leading Component crosses the Galactic plane at a distance from the Sun of 9.5 kpc, about 4.5 kpc from the Galactic Center. Its HI mass may be as high as 10^6 Solar masses, comparable to the mass of the neutral component of the Smith Cloud, but only a fraction of this is contained in clouds that are resolved in the GBT data. Like the Smith Cloud, the Leading Component appears to be adding mass and angular momentum to the ISM in the inner Galaxy. We suggest that the Smith Cloud is not an isolated object, but rather part of a structure that stretches more than 40 degrees (about 7 kpc) across the sky, in two pieces separated by a gap of about 1 kpc. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16598v1

    ١ من الدقائق

  7. ٣٠‏/١١‏/٢٠٢٢

    A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy

    A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy by Vedant Chandra et al. on Wednesday 30 November We report the discovery of Specter, a disrupted ultrafaint dwarf galaxy revealed by the H3 Spectroscopic Survey. We detected this structure via a pair of comoving metal-poor stars at a distance of 12.5 kpc, and further characterized it with Gaia astrometry and follow-up spectroscopy. Specter is a $25^\circ \times 1^\circ$ stream of stars that is entirely invisible until strict kinematic cuts are applied to remove the Galactic foreground. The spectroscopic members suggest a stellar age $\tau \gtrsim 12$ Gyr and a mean metallicity $\langle\text{[Fe/H]}\rangle = -1.84_{-0.18}^{+0.16}$, with a significant intrinsic metallicity dispersion $\sigma_{ \text{[Fe/H]}} = 0.37_{-0.13}^{+0.21}$. We therefore argue that Specter is the disrupted remnant of an ancient dwarf galaxy. With an integrated luminosity $M_{\text{V}} \approx -2.6$, Specter is by far the least-luminous dwarf galaxy stream known. We estimate that dozens of similar streams are lurking below the detection threshold of current search techniques, and conclude that spectroscopic surveys offer a novel means to identify extremely low surface brightness structures. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2207.13717v2

    ١ من الدقائق

  8. ٣٠‏/١١‏/٢٠٢٢

    A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy

    A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy by Vedant Chandra et al. on Wednesday 30 November We report the discovery of Specter, a disrupted ultrafaint dwarf galaxy revealed by the H3 Spectroscopic Survey. We detected this structure via a pair of comoving metal-poor stars at a distance of 12.5 kpc, and further characterized it with Gaia astrometry and follow-up spectroscopy. Specter is a $25^\circ \times 1^\circ$ stream of stars that is entirely invisible until strict kinematic cuts are applied to remove the Galactic foreground. The spectroscopic members suggest a stellar age $\tau \gtrsim 12$ Gyr and a mean metallicity $\langle\text{[Fe/H]}\rangle = -1.84_{-0.18}^{+0.16}$, with a significant intrinsic metallicity dispersion $\sigma_{ \text{[Fe/H]}} = 0.37_{-0.13}^{+0.21}$. We therefore argue that Specter is the disrupted remnant of an ancient dwarf galaxy. With an integrated luminosity $M_{\text{V}} \approx -2.6$, Specter is by far the least-luminous dwarf galaxy stream known. We estimate that dozens of similar streams are lurking below the detection threshold of current search techniques, and conclude that spectroscopic surveys offer a novel means to identify extremely low surface brightness structures. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2207.13717v2

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Daily Astro papers on the arXiv in all categories.

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    Corentin Cadiou
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