445 research outputs found
Unresolved Blazar Component of the Extragalactic Gamma-Ray Background
We present new theoretical estimates of the relative contribution of unresolved blazars and star forming galaxies to the extragalactic gamma-ray background and discuss constraints on the contributions from other possible components. We find that the Fermi data do not rule out a scenario in which the extragalactic gamma-ray background is dominated by emission from unresolved blazars. The spectrum of unresolved FSRQs, when accounting for the energy dependent effects of source confusion, could be consistent with the combined spectrum of the low energy EGRET extragalactic gamma-ray background measurements and the Fermi-LAT measurements above 200 MeV
Neutrino Target-of-Opportunity Sky Coverage and Scheduler for EUSO-SPB2
Very-high-energy neutrinos can be observed by detecting air shower signals.
Detection of transient target of opportunity (ToO) neutrino sources is part of
a broader multimessenger program. The Extreme Universe Space Observatory on a
Super Pressure Balloon 2 (EUSO-SPB2) Mission, launched on May 12, 2023, was
equipped with an optical Cherenkov Telescope (CT) designed to detect up-going
air showers sourced by Earth-skimming neutrinos that interact near the Earth's
limb. Presented here is an overview of the sky coverage and ToO scheduler
software for EUSO-SPB2. By using the balloon trajectory coordinates and setting
constraints on the positions of the Sun and Moon to ensure dark skies, we can
determine if and when a source direction is slightly below the Earth's limb.
From a source catalog, CT scheduling and pointing is performed to optimize the
search for high-energy neutrinos coming from astrophysical sources. Some sample
results for EUSO-SPB2 are shown.Comment: 10 pages, 6 figures, ICRC2023 Conference Proceeding
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Collaborative yet independent: Information practices in the physical sciences
In many ways, the physical sciences are at the forefront of using digital tools and methods to work with information and data. However, the fields and disciplines that make up the physical sciences are by no means uniform, and physical scientists find, use, and disseminate information in a variety of ways. This report examines information practices in the physical sciences across seven cases, and demonstrates the richly varied ways in which physical scientists work, collaborate, and share information and data.
This report details seven case studies in the physical sciences. For each case, qualitative interviews and focus groups were used to understand the domain. Quantitative data gathered from a survey of participants highlights different information strategies employed across the cases, and identifies important software used for research.
Finally, conclusions from across the cases are drawn, and recommendations are made. This report is the third in a series commissioned by the Research Information Network (RIN), each looking at information practices in a specific domain (life sciences, humanities, and physical sciences). The aim is to understand how researchers within a range of disciplines find and use information, and in particular how that has changed with the introduction of new technologies
Summary of the First Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE1)
Challenges related to development, deployment, and maintenance of reusable software for science are becoming a growing concern. Many scientists’ research increasingly depends on the quality and availability of software upon which their works are built. To highlight some of these issues and share experiences, the First Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE1) was held in November 2013 in conjunction with the SC13 Conference. The workshop featured keynote presentations and a large number (54) of solicited extended abstracts that were grouped into three themes and presented via panels. A set of collaborative notes of the presentations and discussion was taken during the workshop.
Unique perspectives were captured about issues such as comprehensive documentation, development and deployment practices, software licenses and career paths for developers. Attribution systems that account for evidence of software contribution and impact were also discussed. These include mechanisms such as Digital Object Identifiers, publication of “software papers”, and the use of online systems, for example source code repositories like GitHub. This paper summarizes the issues and shared experiences that were discussed, including cross-cutting issues and use cases. It joins a nascent literature seeking to understand what drives software work in science, and how it is impacted by the reward systems of science. These incentives can determine the extent to which developers are motivated to build software for the long-term, for the use of others, and whether to work collaboratively or separately. It also explores community building, leadership, and dynamics in relation to successful scientific software
A Hard X-ray Study of the Normal Star-Forming Galaxy M83 with NuSTAR
We present results from sensitive, multi-epoch NuSTAR observations of the
late-type star-forming galaxy M83 (d=4.6 Mpc), which is the first investigation
to spatially resolve the hard (E>10 keV) X-ray emission of this galaxy. The
nuclear region and ~ 20 off-nuclear point sources, including a previously
discovered ultraluminous X-ray (ULX) source, are detected in our NuSTAR
observations. The X-ray hardnesses and luminosities of the majority of the
point sources are consistent with hard X-ray sources resolved in the starburst
galaxy NGC 253. We infer that the hard X-ray emission is most likely dominated
by intermediate accretion state black hole binaries and neutron star low-mass
X-ray binaries (Z-sources). We construct the X-ray binary luminosity function
(XLF) in the NuSTAR band for an extragalactic environment for the first time.
The M83 XLF has a steeper XLF than the X-ray binary XLF in NGC 253, consistent
with previous measurements by Chandra at softer X-ray energies. The NuSTAR
integrated galaxy spectrum of M83 drops quickly above 10 keV, which is also
seen in the starburst galaxies NGC253, NGC 3310 and NGC 3256. The NuSTAR
observations constrain any AGN to be either highly obscured or to have an
extremely low luminosity of 10 erg/s (10-30 keV), implying it
is emitting at a very low Eddington ratio. An X-ray point source consistent
with the location of the nuclear star cluster with an X-ray luminosity of a few
times 10 erg/s may be a low-luminosity AGN but is more consistent with
being an X-ray binary.Comment: Accepted for publication in ApJ (25 pages, 17 figures
Report on the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3)
This report records and discusses the Third Workshop on Sustainable Software
for Science: Practice and Experiences (WSSSPE3). The report includes a
description of the keynote presentation of the workshop, which served as an
overview of sustainable scientific software. It also summarizes a set of
lightning talks in which speakers highlighted to-the-point lessons and
challenges pertaining to sustaining scientific software. The final and main
contribution of the report is a summary of the discussions, future steps, and
future organization for a set of self-organized working groups on topics
including developing pathways to funding scientific software; constructing
useful common metrics for crediting software stakeholders; identifying
principles for sustainable software engineering design; reaching out to
research software organizations around the world; and building communities for
software sustainability. For each group, we include a point of contact and a
landing page that can be used by those who want to join that group's future
activities. The main challenge left by the workshop is to see if the groups
will execute these activities that they have scheduled, and how the WSSSPE
community can encourage this to happen
POEMMA: Probe Of Extreme Multi-Messenger Astrophysics
The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being
designed to establish charged-particle astronomy with ultra-high energy cosmic
rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of
UHECRs and CTNs from space will yield orders-of-magnitude increase in
statistics of observed UHECRs at the highest energies, and the observation of
the cosmogenic flux of neutrinos for a range of UHECR models. These
observations should solve the long-standing puzzle of the origin of the highest
energy particles ever observed, providing a new window onto the most energetic
environments and events in the Universe, while studying particle interactions
well beyond accelerator energies. The discovery of CTNs will help solve the
puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics
with the study of neutrino properties at ultra-high energies.Comment: 8 pages, in the Proceedings of the 35th International Cosmic Ray
Conference, ICRC217, Busan, Kore
Performance and science reach of the Probe of Extreme Multimessenger Astrophysics for ultrahigh-energy particles
The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is a potential
NASA Astrophysics Probe-class mission designed to observe ultra-high energy
cosmic rays (UHECRs) and cosmic neutrinos from space. POEMMA will monitor
colossal volumes of the Earth's atmosphere to detect extensive air showers
(EASs) produced by extremely energetic cosmic messengers: UHECRs above 20 EeV
over the full sky and cosmic neutrinos above 20 PeV. We focus most of this
study on the impact of POEMMA for UHECR science by simulating the detector
response and mission performance for EAS from UHECRs. We show that POEMMA will
provide a significant increase in the statistics of observed UHECRs at the
highest energies over the entire sky. POEMMA will be the first UHECR
fluorescence detector deployed in space that will provide high-quality
stereoscopic observations of the longitudinal development of air showers.
Therefore, it will be able to provide event-by-event estimates of the
calorimetric energy and nuclear mass of UHECRs. The particle physics in the
interactions limits the interpretation of the shower maximum on an event by
event basis. In contrast, the calorimetric energy measurement is significantly
less sensitive to the different possible final states in the early
interactions. We study the prospects to discover the origin and nature of
UHECRs using expectations for measurements of the energy spectrum, the
distribution of arrival direction, and the atmospheric column depth at which
the EAS longitudinal development reaches maximum. We also explore supplementary
science capabilities of POEMMA through its sensitivity to particle interactions
at extreme energies and its ability to detect ultra-high energy neutrinos and
photons produced by top-down models including cosmic strings and super-heavy
dark matter particle decay in the halo of the Milky Way.Comment: 40 pages revtex, with 42 figure
A Focused, Hard X-ray Look at Arp 299 with NuSTAR
We report on simultaneous observations of the local starburst system Arp 299
with NuSTAR and Chandra, which provides the first resolved images of this
galaxy up to energies of ~ 45 keV. Fitting the 3-40 keV spectrum reveals a
column density of ~ 4 x10^{24} cm^{-2}, characteristic of a
Compton-thick AGN, and a 10-30 keV luminosity of 1.2x 10^{43} ergs s^{-1}. The
hard X-rays detected by NuSTAR above 10 keV are centered on the western
nucleus, Arp 299-B, which previous X-ray observations have shown to be the
primary source of neutral Fe-K emission. Other X-ray sources, including Arp
299-A, the eastern nucleus which is also thought to harbor an AGN, as well as
X-ray binaries, contribute to the 10-20 keV emission from the
Arp 299 system. The lack of significant emission above 10 keV other than that
attributed to Arp 299-B suggests that: a) any AGN in Arp 299-A must be heavily
obscured ( > 10^{24} cm^{-2}) or have a much lower luminosity than
Arp 299-B and b) the extranuclear X-ray binaries have spectra that cut-off
above ~10 keV. Such soft spectra are characteristic of ultraluminous X-ray
(ULX) sources observed to date by NuSTAR.Comment: 9 pages; accepted for publication in Astrophysical Journa
Considerations for creating and annotating the budding yeast Genome Map at SGD: a progress report
The Saccharomyces Genome Database (SGD) is compiling and annotating a comprehensive catalogue of functional sequence elements identified in the budding yeast genome. Recent advances in deep sequencing technologies have enabled for example, global analyses of transcription profiling and assembly of maps of transcription factor occupancy and higher order chromatin organization, at nucleotide level resolution. With this growing influx of published genome-scale data, come new challenges for their storage, display, analysis and integration. Here, we describe SGD's progress in the creation of a consolidated resource for genome sequence elements in the budding yeast, the considerations taken in its design and the lessons learned thus far. The data within this collection can be accessed at http://browse.yeastgenome.org and downloaded from http://downloads.yeastgenome.org
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