In data gathered and analyzed over 13 years, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has found an intriguing low-frequency signal that may be attributable to gravitational waves.
NANOGrav researchers studying the signals from distant pulsars – small, dense stars that rapidly rotate, emitting beamed radio waves, much like a lighthouse – have used radio telescopes to collect data that may indicate the effects of gravitational waves, as reported recently in The Astrophysical Journal Letters.
The NANOGrav Collaboration is greatly saddened by the collapse of the 305-m Arecibo telescope and the event’s impact on the staff and scientists who have worked so hard for so many years to ensure its success. We will miss the telescope itself, as one of our own. Many of our scientific careers began with the training we received and camaraderie we enjoyed at Arecibo, for which we will be forever grateful. We also stand in solidarity with our fellow citizens in Puerto Rico for whom Arecibo has been an inspiration and source of pride for so many years. We urge the National Science Foundation to identify uses for the site and staff, as soon as practicable, that benefit from Arecibo’s unique characteristics and promote its continued inspirational role in STEM fields.
The damage to the NSF’s Arecibo telescope from the falling support cable earlier this month will result in significant disruption to telescope operations, dealing a blow to radio astronomy, planetary science, and aeronomy. Arecibo has been the most sensitive radio telescope in the world for most of the last half century, and a continuing series of upgrades have kept it at the cutting-edge in multiple science areas.
When galaxies merge, the supermassive black holes that reside in those galaxies’ centers may form binaries. After inspiralling for millions of years, those supermassive pairs should eventually coalesce. During that inspiral process, they will emit some of the brightest gravitational waves in the universe. NANOGrav’s first multi-messenger search—that is, a search that uses both light and gravitational-wave information to seek a detection—was undertaken on the candidate binary supermassive black hole in galaxy 3C66B. Previous radio observations had led to the hypothesis that this galaxy contains a supermassive black hole binary. The apparent 1.05-year orbital period for the binary in 3C66B makes it an excellent candidate to analyze with pulsar timing arrays.
We have recently released our latest, 12.5-year data set, which consists of observations from the Arecibo Observatory and the Green Bank Telescope on 47 millisecond pulsars. We have introduced two pulsars into this data set, J1946+3417 and J2322+2057, for which we have timing baselines over 2 years; however, our longest baselines are nearly 13 years in length and make our pulsar timing array sensitive to low-frequency, nanohertz gravitational waves. This data set has two varieties: a “narrowband” version, which is very similar in its form and construction to our previous data sets (the 11-, 9-, and 5-year data sets), and a “wideband” version, which is the first data set of its kind. The timing analyses of the data sets are mutually consistent, and we are in the process of analyzing these data for the presence of gravitational waves.
The data are available on our website, here!
“Spikey”, an exciting new supermassive black hole binary candidate, was featured in Scientific American. Spikey was observed by the Kepler space telescope, and shows an unusual symmetric flare. This flare is well explained by relativistic self-lensing in a binary system, when the smaller supermassive BH passes behind the bigger one. If the flare repeats in the upcoming months, the binary nature of the candidate will be confirmed. The paper was led by graduate student Betty Hu, and co-authored by NANOGrav post-doctoral fellow Maria Charisi.
Newly published results! NANOGrav searches 11-year data set for unique gravitational wave signature – gravitational wave memory.
Read more in The Astrophysical Journal.
Special Session approved, “New Results From The North American Nanohertz Observatory for Gravitational Waves”
235th meeting of the American Astronomical Society Honolulu, HI 5 January 2020
This Special Session will highlight advancements in the search for nanohertz gravitational waves using pulsar-timing arrays, and the exciting multi-messenger opportunities to probe supermassive binary black holes. The session will include three invited talks followed by a panel discussion.
Summary: Astronomers using the GBT have discovered the most massive neutron star to date, a rapidly spinning pulsar approximately 4,600 light-years from Earth. This record-breaking object is teetering on the edge of existence, approaching the theoretical maximum mass possible for a neutron star. “Neutron stars are as mysterious as they are fascinating,” said Thankful Cromartie, a graduate student at the University of Virginia and Grote Reber doctoral fellow at the National Radio Astronomy Observatory in Charlottesville, Virginia. “These city-sized objects are essentially ginormous atomic nuclei. They are so massive that their interiors take on weird properties. Finding the maximum mass that physics and nature will allow can teach us a great deal about this otherwise inaccessible realm in astrophysics.”
Read more at the NRAO website.
The NANOGrav Collaboration congratulates the Event Horizon Telescope team for their success in creating a spectacular first direct image of the supermassive black hole at the center of galaxy M87. NANOGrav members James Cordes and Shami Chatterjee are also members of the EHT collaboration pulsar working group, which focuses on finding pulsars around the supermassive black hole at the center of the Milky Way galaxy. This measurement represents the culmination of a 10-year effort and a number of technological and scientific advancements, not least of which is the proof that supermassive black holes of millions to billions of times the mass of the sun are in fact the engines of intense gravity and light in the centers of many galaxies. For years astronomers have seen the “smoking gun” from these compact titans in the form of large-scale radio jets and intensely glowing X-rays, but the EHT result has delivered the first direct image of the heart of one of these objects. NANOGrav is involved in a long-standing effort to directly detect not just one, but two supermassive black holes in a tight orbit. This detection will be made not through their light, but through the effect of their gravitational waves on radio pulses from celestial clocks called pulsars.
For the past twelve years, a group of astronomers have been watching the sky carefully, timing pulses of radio waves being emitted by rapidly spinning stars called pulsars, first discovered 50 years ago. These astronomers are interested in understanding pulsars, but their true goal is much more profound; the detection of a new kind of gravitational waves. With a new, more sophisticated analysis, they are much closer than ever before.
NANOGrav congratulates our LIGO colleagues and their collaborators across the electromagnetic spectrum on another milestone of modern astronomy: the first detection of a merger of two neutron stars. This first detection of an object in both light and gravitational waves is a remarkable feat and demonstrates the unique power of uniting these two methods to explore our Universe.
Special Session approved, and contributed papers welcome “Merging Galaxies and Gravitational Waves: From Mpc to mpc”
229th meeting of the American Astronomical Society
6 January 2017
This Special Session will highlight advancements in astrophysics in the low frequency gravitational waveband and will feature a mix of invited and contributed oral presentations and posters.
New results from NANOGrav – the North American Nanohertz Observatory for Gravitational Waves – establish astrophysically significant limits in the search for low-frequency gravitational waves.
NANOGrav congratulates our LIGO colleagues on their discovery of gravitational waves from a binary black hole system. This result is a major milestone, not only in the field of gravitational-wave astronomy, but in the history of science!
The National Science Foundation (NSF) has awarded the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) $14.5 million over 5 years to create and operate a Physics Frontiers Center (PFC).