scholarly journals Fermi: Monitoring the Gamma-Ray Universe

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 117 ◽  
Author(s):  
David Thompson
Keyword(s):  
Response Time ◽  
Real Time ◽  
Gamma Ray ◽  
High Redshift ◽  
Large Area ◽  
Long Duration ◽  
Level Data ◽  
High Level ◽  
Atmospheric Phenomena ◽  
Scientific Return

Since 2008, the Large Area Telescope and the Gamma-ray Burst Monitor on the Fermi Gamma-ray Space Telescope have been monitoring the entire sky at energies from about 8 keV to more than 1 TeV. Photon-level data and high-level data products are made publicly available in near-real time, and efforts continue to improve the response time. This long-duration, all-sky monitoring has enabled a broad range of science, from atmospheric phenomena on Earth to signals from high-redshift sources. The Fermi instrument teams have worked closely with multiwavelength and multi-messenger observers and theorists to maximize the scientific return from the observatory, and they look forward to continued cooperative efforts as Fermi moves into its second decade of operation.

scholarly journals Exploration of the high-redshift universe enabled by THESEUS

2021 ◽  
Author(s):  
N. R. Tanvir ◽  
E. Le Floc’h ◽  
L. Christensen ◽  
J. Caruana ◽  
R. Salvaterra ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Long Duration ◽  
Absorption Studies ◽  
Population Iii Stars ◽  
High Redshift Universe

AbstractAt peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar and intergalactic medium back to the reionization era. The proposed THESEUS mission is designed to detect large samples of GRBs at z > 6 in the 2030s, at a time when supporting observations with major next generation facilities will be possible, thus enabling a range of transformative science. THESEUS will allow us to explore the faint end of the luminosity function of galaxies and the star formation rate density to high redshifts; constrain the progress of re-ionisation beyond $z\gtrsim 6$ z ≳ 6 ; study in detail early chemical enrichment from stellar explosions, including signatures of Population III stars; and potentially characterize the dark energy equation of state at the highest redshifts.

scholarly journals The Science Case for PILOT II: the Distant Universe

2009 ◽  
Vol 26 (4) ◽  
pp. 397-414 ◽  
Author(s):  
J. S. Lawrence ◽  
M. C. B. Ashley ◽  
A. Bunker ◽  
R. Bouwens ◽  
D. Burgarella ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
High Sensitivity ◽  
Infrared Light ◽  
Wide Field ◽  
Atmospheric Conditions ◽  
Large Area ◽  
Optical Telescope ◽  
Infrared Telescope ◽  
Scientific Potential

AbstractPILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the distant (redshift >1) Universe, that have been identified as key science drivers for the PILOT facility. The potential for PILOT to detect the first populations of stars to form in the early Universe, via infrared projects searching for pair-instability supernovae and gamma-ray burst afterglows, is investigated. Two projects are proposed to examine the assembly and evolution of structure in the Universe: an infrared survey searching for the first evolved galaxies at high redshift, and an optical survey aimed at characterising moderate-redshift galaxy clusters. Finally, a large-area weak-lensing survey and a program to obtain supernova infrared light-curves are proposed to examine the nature and evolution of dark energy and dark matter.

scholarly journals GRB 130427A: A Nearby Ordinary Monster

Science ◽  
2013 ◽  
Vol 343 (6166) ◽  
pp. 48-51 ◽  
Author(s):  
A. Maselli ◽  
A. Melandri ◽  
L. Nava ◽  
C. G. Mundell ◽  
N. Kawai ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
High Redshift ◽  
Full Range ◽  
Gamma Ray Bursts ◽  
Central Engine ◽  
Long Duration ◽  
Relative Proximity ◽  
Γ Ray ◽  
Burst Emission

Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ∼ 3 × 1053 ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies.

scholarly journals Open high-level data formats and software for gamma-ray astronomy

2017 ◽  
Author(s):  
Christoph Deil ◽  
Catherine Boisson ◽  
Karl Kosack ◽  
Jeremy Perkins ◽  
Johannes King ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Astronomy ◽  
Data Formats ◽  
Level Data ◽  
High Level

scholarly journals Simulating High-Redshift Disk Galaxies: Applications to Long Duration Gamma-Ray Burst Hosts

2008 ◽  
Vol 4 (S254) ◽  
pp. 35-40
Author(s):  
Brant E. Robertson
Keyword(s):  
Star Formation ◽  
Molecular Hydrogen ◽  
Gamma Ray ◽  
High Redshift ◽  
Disk Galaxies ◽  
Host Galaxies ◽  
Long Duration ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
The Impact

AbstractThe efficiency of star formation governs many observable properties of the cosmological galaxy population, yet many current models of galaxy formation largely ignore the important physics of star formation and the interstellar medium (ISM). Using hydrodynamical simulations of disk galaxies that include a treatment of the molecular ISM and star formation in molecular clouds (Robertson & Kravtsov 2008), we study the influence of star formation efficiency and molecular hydrogen abundance on the properties of high-redshift galaxy populations. In this work, we focus on a model of low-mass, star forming galaxies at 1 ≲ z ≲ 2 that may host long duration gamma-ray bursts (GRBs). Observations of GRB hosts have revealed a population of faint systems with star formation properties that often differ from Lyman-break galaxies (LBGs) and more luminous high-redshift field galaxies. Observed GRB sightlines are deficient in molecular hydrogen, but it is unclear to what degree this deficiency owes to intrinsic properties of the galaxy or the impact the GRB has on its environment. We find that hydrodynamical simulations of low-stellar mass systems at high-redshifts can reproduce the observed star formation rates and efficiencies of GRB host galaxies at redshifts 1 ≲ z ≲ 2. We show that the compact structure of low-mass high-redshift GRB hosts may lead to a molecular ISM fraction of a few tenths, well above that observed in individual GRB sightlines. However, the star formation rates of observed GRB host galaxies imply molecular gas masses of 108 – 109M⊙ similar to those produced in the simulations, and may therefore imply fairly large average H2 fractions in their ISM.

scholarly journals Environments of massive stars and the upper mass limit

2011 ◽  
Vol 7 (S279) ◽  
pp. 9-17
Author(s):  
Paul A. Crowther
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
High Redshift ◽  
Star Clusters ◽  
Stellar Mass ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Mass Limit ◽  
Host Galaxies ◽  
Long Duration

AbstractThe locations of massive stars (≥ 8M⊙) within their host galaxies is reviewed. These range from distributed OB associations to dense star clusters within giant Hii regions. A comparison between massive stars and the environments of core-collapse supernovae and long duration Gamma Ray Bursts is made, both at low and high redshift. We also address the question of the upper stellar mass limit, since very massive stars (VMS, Minit ≫ 100M⊙) may produce exceptionally bright core-collapse supernovae or pair instability supernovae.

Real-time image-content-based beamline control for smart 4D X-ray imaging

2016 ◽  
Vol 23 (5) ◽  
pp. 1254-1263 ◽  
Author(s):  
Matthias Vogelgesang ◽  
Tomas Farago ◽  
Thilo F. Morgeneyer ◽  
Lukas Helfen ◽  
Tomy dos Santos Rolo ◽  
...  
Keyword(s):  
Real Time ◽  
High Speed ◽  
Image Data ◽  
Building Blocks ◽  
Level Control ◽  
Real Time Processing ◽  
X Ray ◽  
Level Data ◽  
High Level

Real-time processing of X-ray image data acquired at synchrotron radiation facilities allows for smart high-speed experiments. This includes workflows covering parameterized and image-based feedback-driven control up to the final storage of raw and processed data. Nevertheless, there is presently no system that supports an efficient construction of such experiment workflows in a scalable way. Thus, here an architecture based on a high-level control system that manages low-level data acquisition, data processing and device changes is described. This system is suitable for routine as well as prototypical experiments, and provides specialized building blocks to conduct four-dimensionalin situ,in vivoandoperandotomography and laminography.

scholarly journals Radio VLBA polarization and multiband monitoring of the high-redshift quasar S5 0836 + 710 during a high-activity period

2019 ◽  
Vol 491 (1) ◽  
pp. 858-873 ◽  
Author(s):  
M Orienti ◽  
F D’Ammando ◽  
M Giroletti ◽  
D Dallacasa ◽  
G Giovannini ◽  
...  
Keyword(s):  
High Activity ◽  
Gamma Ray ◽  
High Redshift ◽  
Activity Period ◽  
X Rays ◽  
Large Area ◽  
The Core ◽  
Rotation Measure ◽  
Spectrum Radio ◽  
Γ Ray

ABSTRACT We report on results of a multiband monitoring campaign from radio to γ-rays of the high-redshift flat spectrum radio quasar S5 0836 + 710 during a high-activity period detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Two major flares were detected, in 2015 August and November. In both episodes, the apparent isotropic γ-ray luminosity exceeds 1050 erg s−1, with a doubling time-scale of about 3 h. The high γ-ray activity may be related to a superluminal knot that emerged from the core in 2015 April at the peak of the radio activity and is moving downstream along the jet. The low variability observed in X-rays may indicate that X-ray emission is produced by the low-energy tail of the same electron population that produces the γ-ray emission. The analysis of full-polarization pc-scale radio observations suggests the presence of a limb-brightened polarization structure at about 1 mas from the core in which a rotation measure gradient with a sign change is observed transverse to the jet direction. These characteristics are consistent with a scenario in which Faraday rotation is produced by a sheath of thermal electrons with a toroidal magnetic field surrounding the emitting jet.

scholarly journals Towards open and reproducible multi-instrument analysis in gamma-ray astronomy

2019 ◽  
Vol 625 ◽  
pp. A10 ◽  
Author(s):  
C. Nigro ◽  
C. Deil ◽  
R. Zanin ◽  
T. Hassan ◽  
J. King ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Data Format ◽  
Cherenkov Telescopes ◽  
Level Data ◽  
Combining Data ◽  
Very High Energy ◽  
High Level ◽  
The Crab Nebula

The analysis and combination of data from different gamma-ray instruments involves the use of collaboration proprietary software and case-by-case methods. The effort of defining a common data format for high-level data, namely event lists and instrument response functions (IRFs), has recently started for very-high-energy gamma-ray instruments, driven by the upcoming Cherenkov Telescope Array (CTA). In this work we implemented this prototypical data format for a small set of MAGIC, VERITAS, FACT, and H.E.S.S. Crab nebula observations, and we analyzed them with the open-source gammapy software package. By combining data from Fermi-LAT, and from four of the currently operating imaging atmospheric Cherenkov telescopes, we produced a joint maximum likelihood fit of the Crab nebula spectrum. Aspects of the statistical errors and the evaluation of systematic uncertainty are also commented upon, along with the release format of spectral measurements. The results presented in this work are obtained using open-access on-line assets that allow for a long-term reproducibility of the results.

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