Nanoscale gemstones source of mysterious cosmic microwave light
Some of the tiniest diamonds in the universe – bits of crystalline carbon hundreds of thousands of times smaller than a grain of sand – have been detected swirling around three infant star systems in the Milky Way. These microscopic gemstones are neither rare nor precious; they are, however, exciting for astronomers who identified them as the source of a mysterious cosmic microwave “glow” emanating from several protoplanetary disks in our galaxy.
Innovation Advances ‘Phased Array Feed’ Imaging System
The 19-element phased array feed developed by the NRAO CDL. Credit: NRAO/AUI/NSF
To accelerate the pace of discovery and exploration of the cosmos, a multi-institution team of astronomers and engineers has developed a new and improved version of an unconventional radio-astronomy imaging system known as a Phased Array Feed (PAF). This remarkable instrument can survey vast swaths of the sky and generate multiple views of astronomical objects with unparalleled efficiency.
Looking nothing like a camera or other traditional imaging technologies – like CCDs in optical telescopes or single receivers in radio telescopes – this new Phased Array Feed design resembles a forest of miniature tree-like antennas evenly arranged on a meter-wide metal plate. When mounted on a single-dish radio telescope, specialized computers and signal processors are able to combine the signals among the antennas to create a virtual multi-pixel camera.
This type of instrument is particularly useful in a number of important areas of astronomical research, including the study of hydrogen gas raining in on our galaxy and in searches for enigmatic Fast Radio Bursts.
Over the years, various other radio astronomy research facilities have developed phased array receiver designs. Most, however, have not achieved the efficiency necessary to compete with classical radio receiver designs, which process one signal from one spot on the sky at a time. The value of the new PAF is that it can form multiple views (or “beams on the sky,” in radio astronomy terms) with the same efficiency as a classical receiver, which can enable faster scans of multiple astronomical targets.
This newly developed system helps take Phased Array Feed technology from a curious area of research to a highly efficient, multipurpose tool for exploring the universe.
Infographic demonstrating the layout of the newly designed Phased Array Feed receiver that was tested on the Green Bank Telescope. Credit: NRAO/AUI/NSF; S. Dangello
Commissioning observations with the National Science Foundation’s Green Bank Telescope (GBT) using this new design show that this instrument met and exceeded all testing goals. It also achieved the lowest operating noise temperature – a normally vexing problem for clear views of the sky — of any phased array receiver to date. This milestone is critical to move the technology from an experimental design to a fully fledged observing instrument.
The results are published in the Astronomical Journal.
“When looking at all phased array receiver technologies currently operating or in development, our new design clearly raises the bar and gives the astronomy community a new, more rapid way of conducting large-scale surveys,” said Anish Roshi, an astronomer-engineer with the National Radio Astronomy Observatory (NRAO) and a member of the design team.
The new PAF was designed by a consortium of institutions: the NRAO’s Central Development Laboratory, Green Bank Observatory, and Brigham Young University.
“The collaborative work that went into designing, building, and ultimately verifying this remarkable system is truly astounding,” said NRAO Director Tony Beasley. “It highlights the fact that new and emerging radio astronomy technology can have an immense impact on research.”
Close-up of dipole antennas on the Phased Array Feed. Credit: NRAO/AUI/NSF
The new PAF design consists of 19 dipole antennas, radio receivers that resemble miniature umbrellas without a covering. A dipole, which simply means “two poles,” is the most basic type of antenna. Its length determines the frequency — or wavelength of radio light — it is able to receive. In the PAF radio system, the strength of the signal can vary across the surface of the array. By calculating how the signal is received by each of the antennas, the system produces what is known as a “point-spread function” – essentially, a pattern of dots concentrated in one region.
The PAF’s computer and signal processors can calculate up to seven point-spread functions at a time, enabling the receiver to synthesize seven individual beams on the sky. The new design also allows these regions to overlap, creating a more comprehensive view of the region of space being surveyed.
“This project brings together in one instrument a state-of-the-art, low-noise receiver design, next generation multi-channel digital radio technology, and advanced phased array modeling and beamforming,” said Bill Shillue, PAF group lead at the NRAO’s Central Development Laboratory.
The astronomical value of the receiver was demonstrated by GBT observations of the pulsar B0329+54 and the Rosette Nebula, a star-forming region of the Milky Way filled with ionized hydrogen gas.
Additional development and computing power could enable this same design to generated an even greater number of beams on the sky, greatly expanding its utility.
The Green Bank Observatory and National Radio Astronomy Observatory are facilities of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
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This research is presented in a paper titled “Performance of a highly sensitive, 19-element, dual-polarization, cryogenic L-band phased array feed on the Green Bank Telescope,” by D.A. Roshi, et al., which appears in the Astronomical Journal. [https://doi.org/10.3847/1538-3881/aab965]
Contact:
Charles Blue, Public Information Officer
(434) 296-0314; cblue@nrao.edu
Spring is here in Green Bank, at least in theory (and if it would stop snowing that would be nice). This means we are now ramping up for our influx of summer staff and the many summer programs which we host on site. From workshops on single dish radio astronomy for undergraduate and graduate students, to REU and internship positions, summer camps for teachers and students, amateur astronomy gatherings, Pulsar Search Collaboratory meetings and training, and the annual Space Race Rumpus bike weekend, there is something for almost everyone going on here during the summer months. During this summer we are also spending time looking toward the future of the Observatory. As you will see in the ASTRO2020 article within this newsletter, we are actively soliciting input from the scientific community to help us shape our future and working with plan for what Green Bank Observatory should look like in 2020 and beyond.
Enjoy Your Spring!
Karen O’Neil
Director
News
Expression of Interest Invitation
Green Bank Observatory, LBO and NRAO invite submissions of brief Expressions of Interest (EoI) in PI-led “eXtra Large Proposals” (X-Proposals) for the GBT, VLBA and VLA requiring 1000 hours or more of telescope time, and running over multiple semesters (and possibly multiple VLA configurations).
X-Proposals are expected to be resourced by the proposing team. Projects should have extraordinary scientific merit and community legacy value, and will be expected to specify why the science goals cannot be achieved through the standard SRP/TAC process.
Responses will be used to gauge the level of community interest in such proposals, and their scientific potential. The observatories may not proceed to a Call for X-Proposals if, for example, there is judged to be insufficient community interest, scientific merit, or differentiation from Large Proposals.
The call for submission of EoIs is expected to be issued on June 1 with a deadline of July 11.
See the 2016 and 2017 NRAO User Committee reports for further background.
REU Students coming to Green Bank
Green Bank Observatory will be welcoming eight summer students in late May as part of the Research Experience for Undergraduates (REU) program and the Physicists Inspiring the Next Generation (PING) program. Students will be joining scientific and engineering staff for 10-12 week research projects and professional development activities. PING students will also spend one week mentoring middle school students participating in a science camp at the observatory. This core component of PING is designed to enhance the participation of underrepresented minorities in Science, Technology, Engineering, and Mathematics (STEM) fields. The Green Bank Observatory will also be welcoming a graduate intern working in the digital electronics group.
Astro2020 Update
The Green Bank Observatory kicked off plans for the Astro2020 Decadal Survey at the Winter AAS Meeting in Washington, DC. The effort started with the “Transformative Science for the Next Decade with the Green Bank Observatory” workshop in October 2017, which identified some key science drivers for the Observatory in the next decade. At the AAS meeting, Observatory science staff conducted an information-gathering session along with many of those very important booth and hallway conversations that spark new ideas. In January, we announced the Astro2020 activities for Green Bank with a letter from the Director to all who participated in the workshop and AAS activities to join the Observatory in crafting a series of science white papers in anticipation of a late 2018 call for papers. Science interests have been divided into seven scientific discussion categories and we are establishing teams for each category to identify key science cases and develop papers. The categories are:
Fundamental Physics (e.g. gravitational waves, general relativity, equivalence principle)
The transient sky (e.g. FRBs, SETI, Pulsars )
Stars & star formation (e.g. turbulence, magnetic fields, multi-scale molecular clouds, diffuse environments, ISM)
Galaxies & Galaxy Clusters (Milky Way and beyond) (e.g. cosmic web, HI extent of galaxies, galaxy structure, galaxy clusters)
Planetary systems (e.g. sun, stars, asteroid, comets, exoplanets, planetary weather/atmosphere)
Cosmology & Large Scale Structure
Response has been excellent with more than 60 scientists and astronomy professionals signing up for one or more discussion groups. We encourage anyone with interest in future science at Green Bank to join the Astro2020 team. More information about the Astro2020 program and information for interested participants is available at on our ASTRO2020 page.
We hope to hear from you. We will keep you posted on the progress of the teams in upcoming newsletter articles.
Pulsar Watchers Close In On Galaxy Merger History
Fifty years after pulsar discovery published, massive new data set moves closer to finding very-low-frequency gravitational waves, researchers say.
Gravitational waves are wrinkles in space-time that stretch and squeeze the distances between objects. In 2015, a hundred years after Albert Einstein realized that accelerating massive objects should produce them, these waves were finally detected from black holes with masses roughly 30 times the mass of our sun colliding with each other. However, Einstein’s theory also predicts another kind of wave, one that comes from the mergers of black holes with masses of hundred million times the sun’s.
Astronomers Solve Cosmic “Whodunit” with Interstellar Forensics
On the outskirts of our galaxy, a cosmic tug-of-war is unfolding. The players are two dwarf galaxies, the Large Magellanic Cloud and the Small Magellanic Cloud, both of which orbit our own Milky Way Galaxy. But as they go around the Milky Way, they are also orbiting each other. Each one tugs at the other, and one of them has pulled out a huge cloud of gas from its companion.
Solar System’s Largest Telescope Sees New Black Hole Details
Part of the global network of ground radio telescopes that participated in the observations. Credit: Paul Boven (boven@jive.eu). Satellite image: Blue Marble Next Generation, courtesy of NASA Visible Earth (visibleearth.nasa.gov)
Using the RadioAstron Space VLBI Telescope, an international consortium of astronomers have been able to observe ten times closer to a black hole and see new details of the jet formation region of Perseus A. These observations challenge some of the current models by showing jets much wider than predicted. The Perseus jets are in their infancy and astronomers plan to continue these ultra-high resolution observations to see how the jets ‘mature’ and compare observations of other active Galactic Nuclei to see how these results compare with other black hole jets.
All of this is possible because the combination of the RadioAstron spacecraft’s 10 meter telescope in orbit between the Moon and Earth, combined with multiple ground telescopes, like the GBT which contributed to the Perseus A observation, is able to resolve details beyond the capabilities of any ground-based telescope or array. Whenever the spacecraft is viewable in our hemisphere, the science data and spacecraft data are conveyed back to Russia by way of the 140’ Telescope acting as a data downlink, often as the GBT is simultaneously observing the same source as the spacecraft. Green Bank is pleased to provide the vital data connection that make observations like these possible.
Coming this Summer – New GBO Post Docs
Natalie Butterfield and Will Armentrout join the GBO Scientific staff in August as our newest Post Docs. Natalie has been an NRAO Reber Fellow attending the University of Iowa, and Will is currently finishing his PhD at West Virginia University with advisor, Loren Anderson. We look forward to their arrival this summer.
GBT Publications, 2018
A complete list of publications are available on this page.
EPO Happenings
Green Bank Observatory Chosen for National Leap Into Science Project
A diverse group of educators from the Green Bank Observatory, West Virginia University Extension Service, Pocahontas County Libraries and the Morgantown Public Library System have teamed up to become The West Virginia Leap into Science State Leadership Team. Out of more than 20 applications from around the nation, West Virginia was one of four state teams selected.
Governor’s School Returns to Green Bank Observatory, under a New Name
After a two-year hiatus, the Green Bank Observatory successfully competed to host the West Virginia Governor’s STEM Institute (GSI) for the next 3 years. GSI invites students to delve into projects that allow them the time and opportunity to think and work like scientists and engineers, using high level mathematics and thinking skills while employing the latest technology. The Green Bank Observatory program “Investigating the Universe”, is an intensive two-week residential program that engages 60 talented rising ninth graders from all over West Virginia in radio astronomy research. Our program is truly unique in that is embedded within the day-to-day workings of a national research center. Our students will have the opportunity to join our professional STEM community; working in teams with scientist-mentors, rubbing elbows with undergraduate students, and using some of the most sophisticated radio astronomy technology on earth.
Physics Inspiring the Next Generation (PING) Camp Accepting Applications
The Green Bank Observatory also hosts a similar camp for rising ninth graders with an interest in STEM from all over the nation. PING is free of charge, except for travel (we do offer shuttle service to and from Green Bank from DC, and Charlottesville VA). We encourage applications from youth who are traditionally under-represented in the STEM fields. Please help us spread the word.
Andrew Seymour officially joined the GBO Scientific Staff in January, 2018. He has been a visiting scientist in Green Bank since hurricane Maria stopped by the Arecibo Observatory for an unwelcomed visit. We talked to Andrew about his career, life in Puerto Rico and his journey to GBO.
Could you briefly explain your Scientific Career journey?
My career has been a bit of a “random walk”. After earning my undergraduate degrees in Mechanical and Aerospace Engineering, I decided to go to graduate school for Physics. There I did research with lasers and optics, then moved on to Chaos theory, but eventually did my thesis work on Astronomy and Pulsars. After graduate school, I moved to Puerto Rico to use the William E. Gordon Telescope at Arecibo, famous for being in the films Goldeneye and Contact, to continue my pulsar work. While there, one of the collaborations that I work with found a millisecond extra-galactic radio source known as a Fast Radio Burst. Follow ups on this source have produced numerous events at Arecibo in the past three years. Yet, this is the sole source to date to repeat, and it is still unknown what is causing these events. All of which has kept the collaboration and me pretty busy.
What was the most fun about working at Arecibo?
Since Arecibo is in the tropics, there was a lot of beach fun to be had. Yet I think I had the most fun with my co-workers. It takes a special personality willing to move to Puerto Rico, and we grew to rely on each other. Be it through a hurricane or the uncertainty of a NSF-EIS, we learned to laugh our way through it all.
Were you involved with any of the projects where Arecibo and the GBT work together? If so, could you talk about them?
There are many projects that use the unique capabilities of both the Arecibo and the Green Bank Telescope.The obvious ones are the Pulsar surveys and Pulsar timing projects. This is where measuring the radio burst from neutron stars can eventually detect gravitational waves from merging super massive black holes, like that found in the center of some galaxies. In order to achieve this, we need a large number of pulsars.
Therefore we want to search far and wide to find them. Arecibo was the largest radio telescope in the world, which allows it to search for very deep and weak pulsars. Yet because of its size, it cannot be tilted, limiting what part of the sky it can observe. Using the largest steerable structure, that is the GBT, is great for finding pulsars in the other part of the sky that Arecibo cannot reach. Arecibo searches the far, while GBT searches the wide.
What is the major difference between Puerto Rico and West Virginia?
The weather.
What are their similarities?
Puerto Rico and West Virginia have more in common than you first realize. Both have their unique dialects. The mountains can make it hard to get where you want to go. Not all the information you need can be found online. Be wary where the GPS sends you. Your cell phone might not work. In spite or maybe because of these “hardships”, both places have a tremendous amount of pride in the region they call home.
May 30 – June 1
2½ day workshop, geared toward college faculty who teach at small non-research colleges or community colleges, and who have an interest in learning about radio astronomy research.
For more info, contact the GBO Education Officer, Sue Ann Heatherly at sheather@nrao.edu
Space Race Rumpus
June 8 – 10
Space Race Rumpus is weekend-long cycling festival, based at the Observatory that raises funds for a Community Wellness Center.
June 4 – 8 For all summer students at NRAO and GBO sites.
ALFALFA-U Workshop
June 19 – 23 This workshop engages undergraduates and their faculty on radio astronomy projects with the ALFALFA Survey data. The workshop is part of an NSF-sponsored program to promote undergraduate research within the ALFALFA project.
ESS Passport Workshop
June 17 – 30 Professional Development workshop to prepare WV teachers to teach 9th grade Earth and Space Science.
A diverse group of educators from the Green Bank Observatory, West Virginia University Extension Service, Pocahontas County Libraries and the Morgantown Public Library System have teamed up to become The West Virginia Leap into Science State Leadership Team. Out of more than 20 applications from around the nation, West Virginia was one of four state teams selected.
Summary: By comparing new Hubble observations with data from the Green Bank Telescope, astronomers have discovered the origin of a huge cloud of gas bridging the Large Magellanic Cloud and the Small Magellanic Cloud, two dwarf galaxies that orbit the Milky Way. In a cosmic version of tug-of-war, the Large Magellanic Cloud is using its added heft to rip away gas from its smaller companion, creating an enormous bow-like feature — known as the Leading Arm – which is crashing onto the outer parts of our galaxy.
