Astrophysics Branch Archive
LIGO-VIRGO Announce New Type of Binary Black Hole Merger
Tyson Littenberg (Astrophysics Branch) is part of the LIGO Scientific Collaboration team that announced the discovery of a new type of binary black hole: GW190412. The signal was recorded on April 12, 2019 during the first month of LIGO-Virgo’s third observing run (O3). GW190412 is a unique event in that the constituent black holes that merged were of very different mass – a ~30 solar mass black hole merging with a ~8 solar mass black hole. All black hole mergers observed previously were consistent with equal mass binaries. Asymmetric mass binaries were predicted to emit gravitational waves at higher-order multipoles of the dominant quadrupole signal. Tests performed on the GW190412 observation unambiguously show the presence of higher order components to the gravitational wave signal consistent with the predictions from Einstein’s general theory of relativity, and marks the first time this phenomena has been observed. GW190412 is only the second O3 event to be published (following the binary neutron star observation GW190425) with dozens of additional candidates going through the LIGO-Virgo vetting process.
The paper and associated data are publicly available for download at https://dcc.ligo.org/LIGO-P190412/public and is accompanied by a numerical relativity simulation of the system viewable at https://www.youtube.com/watch?v=5AkT4bPk-00.
MoonBEAM Proposal Selected for Astrophysics Science SmallSat Studies Program
The “MoonBEAM: A Beyond Earth-orbit Gamma-ray Burst Detector for Multi-Messenger Astronomy” proposal has been selected for a concept study by the Astrophysics Science SmallSat Studies (AS3) program. MoonBeam was submitted in response to NASA’s Research Opportunities in Space Science and is led by ST12’s Michelle Hui. The Marshall Space Flight Center Advanced Concept Office will conduct the mission design study together with the science team.
MoonBEAM is a SmallSat concept of deploying gamma-ray detectors in cislunar space to increase gamma-ray burst detections and improve localization precision with the timing triangulation technique. Such an instrument will probe the extreme processes involved in the cosmic collision of compact objects and facilitate multi-messenger time-domain astronomy to explore the end of stellar life cycles and black hole formation. MoonBEAM’s mission goals are to 1.) detect short gamma-ray bursts associated with gravitational wave events to study astrophysical jets and probe fundamental physics from neutron star merger events, and 2.) improve localization to enable faster afterglow detection to study kilonova evolution and the origin of heavy elements.
MoonBEAM’s in-house science instrument consists of five detector modules, each equipped with phoswiches and silicon photomultipliers positioned on five of the six sides of the instrument to maximize sky coverage. MoonBEAM’s mission is planned for two years (with a one year minimum) and one of the suitable orbits is the cislunar L3 halo orbit of the Earth-Moon system (95,000 – 665,000 km from Earth, 0.3-2.1 light-seconds difference). Based on the sky coverage and duty cycle at Earth-Moon L3 orbit and detector area, MoonBEAM will detect 30-70 short GRBs/year with onboard detection algorithms, competitive with current missions in operation. Adding another instrument in a different orbit will increase the number of GRB detections and improve localization via arrival time difference.
In the image to the right, the purple region showcases the localization improvement of an average GBM detection by MoonBEAM and an instrument in low Earth orbit.
Paper Detailing Improvement to Fermi Gamma-ray Burst Monitor (GBM) Localizations Accepted for Publication
“Evaluation of Automated Fermi GBM Localizations of Gamma-ray Bursts” led by Adam Goldstein (USRA) was accepted for publication in the Astrophysical Journal. This paper details improvements to automated gamma-ray burst localizations provided to the community within 10 minutes of a burst by the RoboBA algorithm developed by the Fermi GBM team. The overall accuracy of RoboBA localizations has been improved significantly. This paper also compares this algorithm to another developed by an outside team. This analysis of more than 500 gamma-ray bursts with known localizations from other satellites shows that the GBM team provided RoboBA algorithm provides confidence regions more than ten times smaller than those provided by the outside group’s algorithms, once systematic uncertainty is considered for both techniques.
Fermi GBM Publishes Follow-up of First LIGO-VIRGO Event Catalog
The Fermi-GBM follow-up analysis of the first LIGO-Virgo gravitational wave catalog (GWTC-1) was published in the Astrophysical Journal on April 20, 2020. The study was led by UAH graduate student and GBM team member Rachel Hamburg and is a collaboration between the full GBM team and the LIGO and Virgo Collaborations. The analysis included deep offline searches of GBM data around the times of all confident gravitational wave detections to identify any potential counterparts. The GRB associated with the binary neutron star merger in LIGO-Virgo’s second observing run (GW1709817/GRB170817a) was found with high confidence, but no “subthreshold” events were discovered in the search. Based on lessons learned from that analysis, improvements to the GBM follow-up algorithms have been implemented and offline searches of new gravitational wave events are ongoing.
Marshall Scientists Support New Video Series
Multiple Marhsall scientists are supporting the US Space and Rocket Center's (USSRC’s) new video series aimed at 10-14 year-olds called “Science Never Stops”. Videos are posted on Facebook and YouTube. ST12 scientists contributing are Tyson Littenberg, Steven Ehlert, and Colleen Wilson-Hodge.
Chandra Project Science team member, Steven Ehlert, gave an interview as part of this digital series. His interview focused on the science mission of the Chandra X-ray Observatory as well as some personal anecdotes. The edited interview video will be made available on the Space and Rocket Center’s social media pages.
Fermi Gamma-ray Burst Monitor (GBM) Paper in Top 10% of Downloads
The First Fermi-GBM Terrestrial Gamma Ray Flash Catalog led by Oliver Roberts (USRA), was in the top 10% of downloaded papers published between January 2018 and December 2019 by the Journal of Geophysical Research: Space Physics. This paper detailed results from 4,144 terrestrial gamma-flashes (TGFs) detected with Fermi GBM from July 11, 2008 through July 31, 2016. TGFs are gamma-rays associated with lightning in thunderstorms. The detection rate of TGFs was about 800 per year on average, with strong correlations with the seasonal variation of lightning. This study quantitatively showed that TGFs occur preferentially near coastlines.
10-Year Compendium of Accreting Pulsar Observations with the Fermi GBM Accepted for Publication
“The Ups & Downs of Accreting X-ray Pulsars: Decade-long Observations with the Fermi Gamma-ray Burst Monitor” led by NASA Postdoctoral Program Fellow Christian Malacaria (USRA) was accepted for publication in the Astrophysical Journal. This paper details observations of 39 accreting X-ray pulsars from August 2008 through November 2019. Accreting pulsars are highly magnetized neutron stars in binary systems with normal star companions. The neutron star accretes mass from its companion onto its poles, emitting X-rays, periodic with the spin period of the neutron star. Fermi GBM observations are vital to our understanding of these systems, revealing long-term cycles, uncovering torque reversals, and providing new orbital solutions.
Universe's Expansion May Not be the Same in All Directions
One of the fundamental ideas of cosmology is that everything looks the same in all directions if you look over large enough distances. A new study using galaxy clusters examines whether the Universe is "isotropic," or the same in all directions. Galaxy Clusters are enormous structures that astronomers can use to measure important cosmological properties. The latest result uses X-ray data from Chandra and X-ray MultiMirror-Newton (XMM-Newton) of hundreds of galaxy clusters. The cluster observations suggest that the Universe may be different depending on which way astronomers look.
For more information see: https://chandra.harvard.edu/photo/2020/isotropic/
Paper accepted for publication in Planetary and Space Science
Steven Ehlert (Astrophysics Branch) is the lead author on a paper accepted for publication in Planetary and Space Science entitled “Measuring Fluxes of Meteor Showers with the NASA All-Sky Fireball Network”. The manuscript was submitted for publication while Dr. Ehlert was in his previous position supporting the Meteoroid Environment Office in the MSFC Natural Environments Branch (EV44)
Black Hole’s Record-breaking Explosion Spotted
On February 27, 2020, Chandra released a new image and press release of the biggest explosion seen in the Universe that astronomers have discovered – the Ophiuchus galaxy cluster. In the center of the Ophiuchus cluster is a large galaxy containing a supermassive black hole. Researchers have traced the source of this gigantic eruption to jets that blasted away from the black hole and carved out a large cavity in the hot gas. Astronomers obtained this result using data from NASA's Chandra X-ray Observatory, XMM-Newton, and two radio telescopes in Australia and India. The explosion released a factor of five more energy than the previous record holder and hundreds of thousands of times more than typical clusters.
For more information see: https://www.nasa.gov/mission_pages/chandra/images/ophiuchus-galaxy-cluster.html.
Colleen Wilson-Hodge Selected as American Astronomical Society (AAS) Legacy Fellow
The American Astronomical society (AAS) has established a new accolade, Fellow of the AAS, to honor members for extraordinary achievement and service over the course of their careers. Dr. Colleen Wilson-Hodge was selected as one of the initial set of Legacy AAS Fellows. The press release is found here https://aas.org/press/aas-announces-first-class-aas-fellows. After this year, there will be an annual selection for this honor. The list of legacy fellows is found here https://aas.org/grants-and-prizes/aas-fellows.
Chandra Data Tests “Theory of Everything”
Astronomers used Chandra to perform a test of string theory, a possible "theory of everything" that would tie all known physics together. The researchers were looking for a type of particle known as an "axion" and other similar particles. Galaxy clusters with their strong magnetic fields and X-ray emission can be excellent places to search for evidence for axions. The team looked at the Perseus galaxy cluster for over 5 days with Chandra, but did not find signals of any axion-like particles.
For more information see: https://chandra.cfa.harvard.edu/photo/2020/perseus/.
A Cosmic Jekyll and Hyde
On February 20, 2020, Chandra released a new image of Terzan 5 CX1, a globular cluster located about 19,000 light years from the earth that has shown behavior traits of two different types of objects. Chandra data from 2003 show this system acted as a low-mass X-ray binary, with a neutron star pulling material from a star like the Sun. In Chandra and VLA data taken from 2009 to 2014, Terzan 5 CX1 showed the system changed into behaving like a millisecond pulsar, then in 2016 went back to acting like a low-mass X-ray binary. To confirm this pattern of "Jekyll and Hyde" behavior, astronomers need to detect radio pulses while Terzan 5 CX1 is faint in X-rays. More radio and X-ray observations are planned to search for this behavior, along with sensitive searches for pulses in existing data. Only three confirmed examples of these identity-changing systems are known, with the first discovered in 2013 using Chandra and several other X-ray and radio telescopes.
For more information see: https://www.nasa.gov/mission_pages/chandra/cosmic-jekyll-and-hyde.html.
Stellar Explosions and Jets Showcased in New 3D Visualizations
On January 29, 2020, the Chandra team released a new collection of 3D visualizations based on data from Chandra and other X-ray telescopes. This compilation of 3D visualizations which includes DG Tau, Cassiopeia A, UScorpii, SN1006, SN 1987A, and Tycho was created by Salvatore Orlando (National Institute for Astrophysics (INAF), Osservatorio Astronomico di Palermo) and his colleagues. These visualizations can teach astronomers about the physical properties of cosmic objects such as their geometry, velocity, and more. Each of these computer simulations is available using free software that is supported by most platforms and browsers and allows users to interact with and navigate 3D models as they choose.
For more information see: https://www.nasa.gov/mission_pages/chandra/main/index.html.
Large Area Burst Polarimeter (LEAP) Selected for Concept Study
On March 16, 2020, Large Area Burst Polarimeter (LEAP), an Astrophysics Mission of Opportunity (MO), was selected for a nine-month implementation concept study. LEAP is an externally mounted International Space Station (ISS) instrument that will study the energetic jets launched during the explosive death of a massive star, or the merger of compact objects such as neutron stars. The LEAP principal investigator (PI) organization is Dr. Mark McConnell/ University of New Hampshire, the deputy PI responsibility is assigned to Marshall’s ST12 Astrophysics Branch, and the project management responsibility is assigned to Marshall’s ST14 Project Management Branch. The project team held a kickoff meeting on March 18, 2020 to review the Phase A schedule and a kickoff with the Explorer’s Project Office will be held on April 23, 2020. The Phase A study will conclude with the delivery of a concept study report in the December time frame.
Progress on IXPE
Marshall scientists, technicians and partners continue to make process on the Imaging X-ray Polarimetry Explorer (IXPE). Recently, the Italian Instrument Team (I2T) at Marshall completed rework and the vibration test of the Detector Unit 2 (DU2), a highly specialized unit that determine the polarization of incident X-rays. The Italian DU2 is flight hardware contributed for use by the IXPE Project and DU2 property custody was transferred from the Italian Space Agency (ASI) to IXPE (NASA).
Also, the Astrophysics Branch, MSFC Engineering, and IXPE Project has validated margin in the mirror module assembly, MMA2, 9394 epoxy bonds using independent engineering groups and cleared the epoxy process used in the MMA final assembly. The IXPE team is ready to begin proto-type level environmental testing. The MMA2 is flight hardware developed by Marshall Space Flight Center for use by the IXPE Project. Following thermal-vacuum (TVAC) testing this flight unit will undergo acoustic and vibration testing before start of X-ray calibration.
Nicole Pelfrey Selected as Marshall's Astrophysics (ST12) Branch Chief
Nicole Pelfrey received a Bachelor of Science degree in biology from Wofford College in 1998. She began her career in the generic pharmaceutical industry, starting as a compliance auditor, leading a microbiology lab and performing research and development for new products. She spent 8 years performing microbiological and chemical testing of drug products. She also served as the assistant quality control laboratory manager for the seventh largest generic pharmaceutical company in the United States. In 2006, she joined the International Space Station (ISS) Payload Operations Team as a Payloads Communications Manager (PAYCOM), collaborating with the ISS crew to ensure successful on-board science operations. She served as PAYCOM team lead for 6 years before shifting her focus to training and organizational management. She served as the operations engineer for an ISS emerging technology development project, supported multiple technical contract proposal teams, developed training for multiple organizations, and supported the Sierra Nevada Dream Chaser vehicle PDR. Her last two years on the ISS Program were as the Operations Manager for the Mission Operations & Integration contract with approximately 300 contractors, 10 direct reports across 5 branches and 24 disciplines. Ms. Pelfrey joined NASA in 2018 as the Deputy Branch Chief of the Astrophysics Branch and began serving as the acting Branch Chief in May 2019. She was recently selected as the Branch Chief in January 2020 to succeed Dr. Nasser Barghouty, who accepted a NASA Headquarters position.
The Fermi Gamma-ray Burst Monitor Releases 10 Year Catalog of Gamma-ray Burst Observations
The Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope has released its 4th Gamma-ray Burst (GRB) catalog, covering over 10 years of observations. Fermi-GBM has been a prolific detector of GRBs; bright flashes of gamma-rays that originate in the distant Universe and are due to the death of massive stars or the inspiral of two compact stellar remnants. The 4th Fermi-GBM GRB catalog includes 2356 bursts, providing a vast trove of information with which scientist can study these unique events. The GBM GRB catalog series provides the community with the most important observables of the GBM detected GRBs, including the location and main characteristics of the prompt emission, duration, peak flux and fluence for each of the cataloged bursts. This 4th catalog is an official product of the Fermi-GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).
The catalog has been accepted to the Astrophysical Journal Supplement Series and will be available on the arXiv pre-print server at the link below.
Galaxy Gathering Brings Warmth
Using NASA’s Chandra X-ray Observatory, European Space Agency's X-ray Multi-Mirror Mission (XMM)-Newton, the Giant Metrewave Radio Telescope (GMRT), and optical observations with the Apache Point Observatory in New Mexico, a team of astronomers has found that two galaxy groups are smashing into each other at a remarkable speed of about 4 million miles per hour. This could be the most violent collision yet seen between two galaxy groups. By studying mergers like this, astronomers can learn more about galaxy groups grow and evolve over time. The system is called NGC 6338, which is located about 380 million light-years from Earth. This composite image contains X-ray data from Chandra (displayed in red) that shows hot gas with temperatures upward of about 20 million degrees Celsius, as well as cooler gas detected with Chandra and XMM (shown in blue) that also emits X-rays. The Chandra data have been combined with optical data from the Sloan Digital Sky Survey, showing the galaxies and stars in white.
The new Chandra and XMM-Newton data also show that the gas to the left and right of the cool cores, and in between them, appears to have been heated by shock fronts -- similar to the sonic booms created by supersonic aircraft -- formed by the collision of the two galaxy groups. This pattern of shock-heated gas has been predicted by computer simulations, but NGC 6338 may be the first merger of galaxy groups to clearly show it. Such heating will prevent some of the hot gas from cooling down to form new stars.
For more information, see: https://www.nasa.gov/mission_pages/chandra/main/index.html.
NASA’s Great Observatories Help Astronomers Build a 3D Visualization of Exploded Star
A Chandra-issued image release on January 5, 2020 combined X-ray, visible and infrared data from NASA's Great Observatories to create a three-dimensional representation of the Crab Nebula. The multiwavelength computer graphics visualization is based on images from the Chandra, Hubble and Spitzer space telescopes. The powerhouse "engine" energizing the entire system is a pulsar, a rapidly spinning neutron star that is shooting blistering pulses of radiation towards us 30 times a second with clockwork precision. A video was created that dissects the intricate nested structure that makes up the stellar corpse, giving viewers a glimpse of the extreme and complex physical processes powering the nebula.
For more information, or to view the video, go to: https://www.nasa.gov/feature/goddard/2019/nasas-great-observatories-help-astronomers-build-a-3d-visualization-of-an-exploded-star.
Black Holes and Baby Stars
On November 18, 2019 Chandra released to the press a featured discovery entitled “A Weakened Black Hole Allows Its Galaxy to Awaken.” The associated image release was featured as the NASA Image of the Day on November 20, 2019. Through this observation of the Phoenix Constellation, astronomers have confirmed the first example of a galaxy cluster where large numbers of stars are being born at its core. More information can be found at the website: https://www.nasa.gov/mission_pages/chandra/images/a-weakened-black-hole-allows-its-galaxy-to-awaken.html.
On November 26, 2019, Chandra released to the press a feature entitled “Black Hole Nurtures Baby Stars a Million Light-Years Away.” The associated image release was featured as the NASA Image of the Day on November 26, 2019. The press release describes one black hole that is influencing the rate of star formation in multiple galaxies and across vast distances. This is a rare example of "positive feedback" where a black hole is helping to spur star formation, not suppress it. Researchers used X-rays from Chandra, radio waves from the VLA, and optical light from ground-based telescopes to make this discovery. If confirmed, this result would represent the largest distance over which a black hole has boosted the birth of stars. More information can be found at the website: https://www.nasa.gov/mission_pages/chandra/images/black-hole-nurtures-baby-stars-a-million-light-years-away.html.
Famous Black Hole has Jet Pushing Cosmic Speed Limit
Chandra data shows that the black hole in the galaxy Messier 87 (M87) is propelling particles away from it faster than 99% the speed of light. These remarkable speeds were detected in changes in the X-ray emission between 2012 and 2017 in regions along a jet generated by the black hole. M87 became famous in April 2019 when the Event Horizon Telescope released the first-ever direct image of its black hole. The jet seen with Chandra is 500,000 times larger and shows much older activity from the black hole than the ring imaged by the EHT.
For more information see: https://chandra.cfa.harvard.edu/photo/2020/m87/.
Marshall scientist presents ground-breaking gamma-ray research at conference in Japan.
Dr. Daniel Kocevski gave an invited talk on the high-energy detection of GRB 190114C at a conference held in Yokohama, Japan. The talk focused on the Fermi and Swift contributions to a paper reporting the first very high-energy detection of a gamma-ray burst (GRB) by ground-based air Cherenkov telescopes. The detection gave high-energy astrophysicists a better understanding of accelerated mechanisms that generate the gamma-rays from these events. The paper has been accepted for publication in the journal Nature.
On January 14, 2019, just before 4:00 p.m. EST, both the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory detected a spike of gamma rays from the constellation Fornax. These distant explosions have produced the highest-energy light yet seen from these events, called gamma-ray bursts, or GRBs. The missions alerted the astronomical community to the location of the burst, dubbed GRB 190114C.
One facility receiving the alerts was the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observatory located on La Palma in the Canary Islands, Spain. Both of its 17-meter telescopes automatically turned to the site of the facing burst. They began observing the GRB just 50 seconds after it was discovered and captured the most energetic gamma rays yet seen from these events. With GRB 190114C, MAGIC became the first facility to report unambiguous very high-energy (VHE) emission, with energies up to a trillion electron volts (1 TeV). That's 10 times the peak energy Fermi has seen to date.
Scientists suspect that most of the gamma rays from GRB afterglows originate in magnetic fields at the jet's leading edge. High-energy electrons spiraling in the fields directly emit gamma rays through a mechanism called synchotron emission. But other scientists, including the MAGIC team, interpret the VHE emission as a distinct afterglow component, which means some additional process must be at work, perhaps inverse Compton scattering. High-energy electrons in the jet crash into lower-energy gamma rays and boost them to much higher energies.
In the paper detailing the Fermi and Swift observations, the researchers conclude that an additional physical mechanism may be needed to produce the VHE emission. Within the lower energies observed by these missions, however, the flood of synchotron gamma rays makes uncovering a second process much more difficult.
Several papers have been published about GRB 190114C. Dr. Kocevski's invited talk presented information from the paper titled "Fermi and Swift Observations for GRB 190114c: Tracing the Evolution of High-Energy Emission from Prompt to Afterglow," for which he was one of the authors.
This paper on the Fermi and Swift contributions can be found at https://arxiv.org/abs/1909.10605.
Additional data and information about MAGIC and GRB 190114C can be found at: https://www.nature.com/articles/s41586-019-1750-x.
Read the Goddard press release here: https://www.nasa.gov/feature/goddard/2019/nasa-s-fermi-swift-missions-enable-a-new-era-in-gamma-ray-science/.
Time Domain Astronomy with the Fermi Gamma-Ray Burst Monitor in the Multimessenger Era presented at Yale University.
On Thursday, November 7, 2019, Dr. Colleen Wilson-Hodge presented an invited Yale Astronomy and Astrophysics Colloquium about the Fermi Gamma-ray Burst Monitor and its exciting science for transients ranging from gravitational wave counterparts to pulsars and magnetars to solar flares and terrestrial gamma-ray flashes. During an impromptu lunchtime talk, when she was asked to speak extemporaneously without slides, she described her experiences with current and future missions for NASA, including the path that led to her involvement in the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X).
To find out more about STROBE-X, go to this site: https://gammaray.nsstc.nasa.gov/Strobe-X/index.html.
To view a link to the seminar, visit: https://astronomy.yale.edu/event/yale-astronomy-astrophysics-colloquium-colleen-wilson-hodge.
Lynx team presented to the ASTRO2020 Panel on the Electromagnetic Observations from Space 2
On November 6, 2018, the Lynx Team presented to the Astro2020 EOS2 panel on the science, technical, and cost of the Lynx mission. Lynx is one of four flagship mission concepts that would launch in the 2030s, after the James Webb Space Telescope and the Wide Field InfraRed Survey Telescope. if prioritized by the Astro2020 Decadal. The Decadal Survey on Astronomy and Astrophysics (Astro2020) is a partnership between the National Academies and the Astronomical community to identify key priorities in astronomy and astrophysics and develop a comprehensive strategy for agency investments in the upcoming decade. Participants from MSFC included Karen Gelmis (ST14), Jessica Gaskin (ST14), and Douglas Swartz (ST12/USRA).
Lynx will provide unprecedented X-ray vision into the otherwise "Invisible" Universe with unique power to directly observe the dawn of supermassive black holes, reveal the drivers of galaxy formation, trace stellar activity including effects on planet habitability, and transform our knowledge of endpoints of stellar evolution.
The clumpy and lumpy death of a star.
A Chandra press release was issued on October 17, 2019 describing new data from Chandra and other telescopes providing a new image of the Tycho supernova remnant from Chandra. The pattern shows bright clumps and fainter holes in the X-ray data. Scientists are trying to determine if this "clumpiness" was caused by the supernova explosion itself or something in tis aftermath. By comparing Chandra data to computer simulations, researchers found evidence that the explosion was likely the source of this lumpy distribution. The original supernova was first seen by skywatchers in 1572, including the Danish astronomer Tycho Brahe for whom the object was eventually named.
For more information go to https://chandra.cfa.harvard.edu/photo/2019/tycho/.
Chandra spots a mega-cluster of galaxies in the making.
A Chandra press release was issued on October 24, 2019, describing a mega-merger of four galaxy clusters in Abell 1758 which was observed by Chandra and other telescopes. Abell 1758 contains two pairs of galaxy clusters, each with hundreds of galaxies embedded in large amounts of hot gas and unseen dark matter. Eventually these two pairs of clusters will collide to form one of the most massive objects in the Universe. The X-rays from Chandra helped astronomers estimate how fast one pair of clusters were moving toward each other.
For more information, go to https://chandra.cfa.harvard.edu/photo/2019/a1758/.
Fermi Gamma-ray Burst Monitor (GBM) continues to follow up unique gravitational wave detections.
September has been an exciting time for the gamma-ray follow up by the Fermi Gamma-ray Burst Monitor of gravitational wave detections. The past four weeks saw the detection of two binary neutron star merger candidates and three neutron star black hole merger candidates by the LIGO Scientific collaboration and the Virgo Collaboration. The merger of two neutron stars has long been thought to be the origin of short GRBs, a theory that was confirmed by the detection of GRB 170817 in both gamma-rays and gravitational waves. It is currently an open question as to whether neutron star black hole mergers could also produce short GRBs, and the past few months have seen the first of these kind of detections by LIGO and Virgo. the GBM did not detect coincident emission from any of the recent binary neutron star or neutron star black hole mergers, but additional observations of such events gives astronomers valuable insight into the ubiquity of electromagnetic emission from such mergers and may be used in the future to constrain theories that aim to explain how these systems work.
Fermi and Swift Observations of GRB 190114C: Tracing the evolution of high-energy emission from prompt to afterglow.
The Fermi Gamma-ray Burst Monitor (GBM) team in Huntsville, working with members of the Fermi Large Area Telescope (LAT) collaboration and the Neil Gehrels Swift Observatory, released a paper on the high-energy observations of gamma-ray burst (GRB) 190114C. GRB 190114C was a unique event in that it was the first GRB ever detected by a ground-based Cherenkov telescope at energies in excess of 1 TeV. Long GRBs result from the explosion of massive stars in distant galaxies and are among the most energetic supernovae ever detected. the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope, located in the Canary Islands, was able to observe the GRB within a minute of its detection by GBM and Swift. The MAGIC observations revealed gamma-ray emission over a million times higher in energy than the emission typically observed by GBM from these events. The combined Fermi and Swift observations placed these VHE observations in context, but providing comprehensive observations at lower energies and revealed how that emission evolved with time.
Using these observations, the Fermi and Swift teams were able to estimate the energy and speed of the relativistic blast wave that was created when the progenitor star went supernova. Being able to measure these properties allowed the Fermi and Swift teams to show that a theory used to explain the emission observed by the GBM and LAT instruments could not also explain the VHE emission observed by MAGIC and that an additional emission mechanism would be needed. The combined observations ultimately allows astronomers to obtain a better understanding of the physics behind the most energetic explosions in the Universe.
You can find the paper online at https://arxiv.org/abs/1909.10605.
Evaluation of Automated Fermi GBM Localizations of Gamma-ray Bursts
The Fermi Gamma-ray Burst Monitor (GBM) detects onboard roughly 240 gamma-ray bursts (GRBs) a year, and the localization of these events and other transients observed by GBM are of prime importance in the era of multi-messenger and time-domain astronomy. To this end, an accurate estimate of the GBM localization uncertainty is a requirement to prevent reporting over-confident localizations that may result in false counterpart associations or lead to ruling out real associations. Therefore, it is important for GBM localizations to be as precise as possible and to account for systematic uncertainty to ensure the overall reported accuracy is reliable.
The GBM team implemented improvements to its automated localization algorithm of GRBs, called RoboBA, and compared the operation of the original and updated version of RoboBA to an alternative, independently-developed localization algorithm, BALROG. Through a systematic study utilizing over 500 GRBs with known locations from instruments like Swift and the Fermi LAT, the GBM team directly compare the effectiveness of, and accurately estimate the systematic uncertainty for, both algorithms.
The GBM team showed that simple adjustments to RoboBA, in operation since early 2016, yields significant improvement in the systematic uncertainty, removing the long tail previously identified in the systematic, and improved the overall accuracy. The systematic uncertainty for the updated RoboBA localizations is 1.8 deg. for 52% of GRBs and 4.1 deg. for the remaining 48%. Both from public reporting by BALROG and the GBM team's systematic study, the systematic uncertainty of 1-2 deg. quoted by the BALROG team for bright GRBs is an underestimate of the true magnitude of the systematic, which is found to be 2.7 deg. for 74% of GRBs and 33 deg. for the remaining 26%. The GBM team showed that, once the systematic uncertainty is considered, the RoboBA 90% localization confidence regions can be more than an order of magnitude smaller in area than those produced by BALROG.
Read the paper online at https://arxiv.org/abs/1909.03006.
The Fermi Gamma-ray Burst Monitor receives positive senior review results.
The Fermi 2019 Senior Review (SR) results have been released and the Fermi mission, including operations of the Gamma-Ray Burst Monitor (GBM), have been extended into 2022. Led by a team at NASA's Marshall Space Flight Center and the University of Alabama in Huntsville, GBM is currently the most prolific detector of transient astrophysical gamma-rays in the sky. The unique, full-sky observational capability of GBM was lauded and Fermi's scientific merit expectations were directly tied to GBM's multi-messenger observations with the Laser Interferometer Gravity Wave Observatory (LIGO) and other gravitational wave observatories. The Fermi Mission was also invited to submit another extended mission proposal for the 2022 SR cycle.
The full astrophysics Senior Review report can be found at: https://science.nasa.gov/astrophysics/2019-senior-review-operating-missions
Chandra's 20th Anniversary!
In 2019, NASA's Chandra X-ray Observatory celebrates its 20th year in space exploring the extreme universe.
Listen to a Public Radio Hour special on Chandra featuring Marshall scientists, Dr. Martin Weisskopf and Dr. Jessica Gaskin, as they join historian Brian Odom to talk about Chandra's discoveries. Just click on the link below.
Marshall X-ray optics will map the X-ray universe.
Scientists and technicians at the Marshall Space Flight Center (MSFC) have designed and fabricated eight Astronomical Roentgen Telescope - X-ray Concentrator (ART-XC) X-ray optics modules that have been launched into space as part of the Spectrum-Roentgen-Gamma (SRG or Spectr-RG observatory) mission. The purpose of this mission is to study the Universe's X-ray range of electromagnetic radiation and create a map of the X-ray Universe including large clusters of galaxies and active galactic nuclei. The SRG mission successfully launched from the Baikonur Cosmodrome on July 13, 2019.
The SRG mission is a Russian-led X-ray astrophysical observatory that carries two, co-aligned, X-ray telescope systems. The extended Roentgen Survey with an Imaging Telescope Array (eROSITA) is the German-led primary instrument for the mission and is a 7-module X-ray telescope system that operates in the 0.2 - 10 KeV band. The complementary instrument is the Astronomical Roentgen Telescope – X-ray Concentrator (ART-XC). This instrument is a seven module X-ray telescope system that operates in the 4-30 KeV energy range.
Marshall Space Flight Center designed and fabricated the seven (and one spare) co-aligned X-ray mirror modules making up the ART-XC telescope. Each module is composed of 28 concentric grazing-incidence mirror shells made using the same electroform-nickel replication process developed at MSFC for numerous space astrophysics and ground-based research applications.
You can learn more about the SRG mission by clicking on the following sites:
LISA Pathfinder sheds new light on interplanetary dust.
Researchers examining LISA Pathfinder data have been able to detect tiny impacts from cosmic dust, identify where the dust came from, and reveal clues to their origin. Read the full article from physicsworld to find out about cosmic dust and the search for gravitational waves.