Left: Color image of the galaxy NGC 4993 — large yellowish object in the center of the frame — and the kilonova — star-like object marked with crosshairs — obtained by the TOROS Collaboration using the T80-South telescope. Right: Color image of the same field after digitally subtracting NGC 4993 and enhancing the contrast. (L. Macri/Texas A&M and the TOROS Collaboration)
Since 2012, Lucas Macri, University of Texas Rio Grande Valley astronomer Mario Díaz and Universidad Nacional de Córdoba astronomer Diego Garcia Lambas have been working to establish a robotic telescope in the Argentine Andes to follow up kilonova explosions. Their collaboration, called the Transient Optical Robotic Observatory of the South (TOROS), involves about 50 astronomers from all over the world. The TOROS telescope and its dome currently are on their way to Argentina and should be operational at some point during 2018. The collaboration plans to upgrade the camera for this telescope during the next few years with a state-of-the-art 100-megapixel device and corrector lenses that will be designed, tested and built by Darren DePoy, Jennifer Marshall and their team within Texas A&M’s Charles R. ’62 and Judith G. Munnerlyn Astronomical Instrumentation Laboratory.
Using the T80-South telescope located at the Cerro Tololo Inter-American Observatory (CTIO) in Chile and the Bosque Alegre telescope located in Argentina, Macri and collaborators studied the fast-fading kilonova at various wavelengths, which is useful to rule out various models for the explosion.
“Contrary to expectations, this kilonova was quite bluish during the first couple of days,” Macri said. “This may mean that not as much radioactive material was produced, or we were looking at the event from above the plane in which the two neutron stars orbited each other.”
Dark Energy Survey
During the course of seven days in Chile, Jennifer Marshall watched the extraordinary event play out in real time through two telescopes — the 4-meter Victor M. Blanco Telescope at CTIO and the 6.5-meter Magellan Telescope at nearby Las Campanas Observatory. She was the only astronomer present and observing on behalf of the U.S. Department of Energy-funded Dark Energy Survey (DES) at Blanco during the unprecedented occurrence.
While in Chile, Marshall got to witness firsthand the fiery aftermath of the explosion while personally recording some of the initial images using the 570-megapixel Dark Energy Camera (DECam), for which Darren DePoy served as the project scientist.
Texas A&M Astronomer Jennifer Marshall Witnesses Cosmic History In Chile
Down at Dome A
Due to relative position of the Sun, Earth and NGC 4993, the kilonova could only be observed for only about 90 minutes after sunset from CTIO and other observatories located at mid-latitudes in the Southern hemisphere. This limitation was not an issue for the team that included Texas A&M astronomers Lifan Wang and Nicholas Suntzeff, who are part of a collaboration with Australian astronomers that conducted immediate follow-up on GW170817 all the way from Dome A in Antarctica, using a fully-robotic telescope called AST3 that is part of the at PLATeau Observatory (PLATO-A) established in 2008.
The uninterrupted polar night enabled Wang and Suntzeff’s team to obtain near-continuous observations of the kilonova, filling in critical gaps at points when no other observatories could image the source.
“I think it’s pretty cool that we can tell a telescope at the coldest place on Earth to look at something of this magnitude,” Suntzeff said.
Darren DePoy, Lucas Macri, Jennifer Marshall, Nicholas Suntzeff and Lifan Wang are co-authors in a mega-paper that summarizes all the worldwide, space-based observations made during that history-making week in August.
Lucas Macri is the corresponding author in a publication that appears today in The Astrophysical Journal Letters detailing the results of the TOROS observations. He also is presenting those results today in Baton Rouge as part of a Gravitational Wave Astrophysics Conference sponsored by the International Astronomical Union and hosted by Louisiana State University. In addition, Macri is featured in several newspapers in his native Argentina, where he participated in an embargoed press conference last week.
Jennifer Marshall is a co-author in nine publications making their debut today. In addition to the two papers mentioned above, her observations appear in two DES-related papers in The Astrophysical Journal Letters as well as two papers in the journal Science featuring the Las Campanas spectra and images. Beyond those, she is an author on three additional DES papers, including one that uses the binary neutron star merger event to estimate the value of the Hubble constant. Darren DePoy is a co-author in four of the DES papers as a DES Builder along with Marshall, who also is a member of the survey’s management and science committees.
Lifan Wang is the corresponding author of a paper published today in Science Bulletin on AST3 observations of GW 170817. Wang and the AST3 team under his leadership is also a part of the Deep Wide and Fast (DWF) survey collaboration that aims to discover optical counterparts of rapid transients arising from gravitational wave and fast radio burst events. The team has access to a broad range of survey telescopes around the globe, from which they acquired spectroscopy that show a rapidly evolving object, with color turning from blue to red extremely fast. Wang also is on a proposal to use the European Space Observatory’s very large telescope to acquire data of the target in the mid infrared. These data and results are published today in Publications of Australia Society of Astronomy.
Lifan Wang and Nicholas Suntzeff are co-authors in a publication that presents the results of the Antarctic observations, as well as another paper written in collaboration with the Australian OzGrav team.
Contact: Shana Hutchins, (979) 862-1237 or firstname.lastname@example.org, Dr. Lucas Macri, (979) 845-7362 or email@example.com, Dr. Jennifer Marshall, (979) 862-2782 or firstname.lastname@example.org, or Dr. Lifan Wang, (979) 845-4881 or email@example.com