Black holes

Various reconstructions of the gravitational waves detected by the LIGO experiment (Image courtesy LIGO experiment)

During a press conference at the American Astronomical Society meeting in San Diego, the second detection of gravitational waves from the merging of two black holes by the LIGO experiment was announced. It is a different event from the first, historic, one announced on February 11, 2016: this time the merger took place about 1.4 billion years ago and was detected on Earth on December 26, 2015. The event is also described in a article published in the journal “Physical Review Letters”.

In the background an image taken by the Hubble Space Telescope. In red the gas seen by ALMA (Image B. Saxton (NRAO/AUI/NSF)/G. Tremblay et al./NASA/ESA Hubble/ALMA (ESO/NAOJ/NRAO))

An article published in the journal “Nature” describes the observation of an intergalactic deluge of gases that from large clouds are falling toward the supermassive black hole at the center of a galaxy in the Abell 2597 cluster. By using the ALMA radio telescope a team of astronomers led by Grant Tremblay of Yale University discovered the first evidence that these huge black holes can gorge on gas through chaotic and clumpy rains of giant clouds of very cold molecular gas.

Artistic representation of a supermassive black hole seed. The inset boxes show a candidate seen by Chandra (top) and by Hubble (bottom) (Image X-ray: NASA/CXC/Scuola Normale Superiore/F. Pacucci, et al. Optical: NASA/STScI. Illustration: NASA/CXC/M. Weiss)

An article that will be published in the journal “Monthly Notices of the Royal Astronomical Society” describes a research on the origin of supermassive black holes. A team of Italian scientists led by Fabio Pacucci of Scuola Normale Superiore of Pisa used NASA’s space telescopes to identify two ancient objects that represent the best candidates black hole “seeds” found so far.