Researchers Find Out Why A Supermassive Black Hole Appears To Move

Researchers often assume that massive galaxies host supermassive black holes (SMBHs) in their nuclei. In recent years, observers have sought galaxies that might contain an SMBH that is displaced from its equilibrium position. Among the scenarios that could cause such a displacement are the merger of two SMBHs or the existence of a binary pair of SMBHs, and finding an example would give astronomers information about the evolution of galaxies and the frequency of the formation and mergers of this type of object.

One of the candidates for a displaced SMBH is the giant elliptical galaxy M87, which contains one of the nearest and most studied galactic nuclei (AGN). Previous studies on the displacement of the SMBH of M87 produced conflicting results. However a new study by Elena López Návas, a student at the University of La Laguna, has produced new data suggesting that the SMBH in this galaxy is in its equilibrium position, and that the displacements found previously were due to variations in the centre of production of light, the “photocentre” caused by outbursts from its relativistic jet, a flow of material expelled from near the surface of the black hole at velocities close to light speed.

To perform this research, it was necessary to analyze a large number of high-resolution images of M87 taken at different times and with different instruments on the NASA/ESA Hubble Space Telescope (HST) and on ESA’s Very Large Telescope (VLT) (Cerro Paranal, Chile).

“In our work, we have found that the SMBH has been in a very stable position for the past 20 years. What has changed is the centre of light production, the'”photocentre,”” explains López, the author of this study, which has just been published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).

“As a result of what we have found, we realised that the images which appeared to show a displacement of the centre of the galaxy were taken at an epoch when M87 had a major outburst, which could be measured over the whole range of the electromagnetic spectrum,” says Almudena Prieto Escudero, co-author of the article and a researcher at the Instituto de Astrofísica de Canarias (IAC).

This outburst took place between the years 2003 and 2007 in a knot within the jet known as HST-1, the closest knot to the nucleus of M87. While this outburst lasted, this knot increased in brightness so much that it even outshone the nucleus itself.

“A time series analysis of the displacements of the centre of the galaxy show that this outburst is related to the change in the position of the photocentre,” explains the astrophysicist. “But afterward, the photocentre and the nucleus were in the same place, so that we inferred that the nucleus and the black hole were always in the same place, which is the potential mínimum at the centre of the galaxy.”

These new data have inspired much interest in the astrophysical community, because studying the position of the SMBH in M87 is critical for understanding the evolution of the galaxy, and for the analysis of jets in other AGNs. “In addition, this research reminds us that we must be very careful when we study variable sources that show irregularities,such as this enormous jet,” says Lopez, who is now working with a training research contract at the IAC.

UPDATE: Geomagnetic Storm for May 6, 2018

Geomagnetic K-Index of 6 expected on May 6th 2018. Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.

Potential Impacts are as follows: Induced Currents – Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms. Spacecraft – Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.

Radio – HF (high frequency) radio propagation can fade at higher latitudes. Aurora – Aurora may be seen as low as New York to Wisconsin to Washington state.

May 4th 2018 Geomagnetic Report:
Cutting across half of the solar disk, a wide hole in the Sun’s atmosphere is turning toward Earth and spewing a stream of solar wind toward our planet. This extreme ultraviolet image from NASA’s Solar Dynamics Observatory shows the gaseous canyon.

This is a coronal hole – a region where the Sun’s magnetic field opens up and allows gaseous material to escape. It looks dark because the hot glowing gas previously contained there is missing. NOAA forecasters say G1-class geomagnetic storms are possible when the solar wind arrives on May 6th or 7th. High-latitude sky watchers should be alert for auroras, especially in the southern hemisphere when deepening autumn darkness favors visibility of Southern Lights. Free: Aurora Alerts.

 

 

 

Scientists Crack 70-Year-Old Mystery Of How Magnetic Waves Heat The Sun

Scientists at Queen’s University Belfast have led an international team to the ground-breaking discovery that magnetic waves crashing through the sun may be key to heating its atmosphere and propelling the solar wind.

The sun is the source of energy that sustains all life on Earth but much remains unknown about it. However, a group of researchers at Queen’s have now unlocked some mysteries in a research paper, which has been published in Nature Physics.

In 1942, Swedish physicist and engineer Hannes Alfvén predicted the existence of a new type of wave due to magnetism acting on a plasma, which led him to obtain the Nobel Prize for Physics in 1970. Since his prediction, Alfvén waves have been associated with a variety of sources, including nuclear reactors, the gas cloud that envelops comets, laboratory experiments, medical MRI imaging and in the atmosphere of our nearest star – the sun.

Scientists have suggested for many years that these waves may play an important role in maintaining the sun’s extremely high temperatures but until now had not been able to prove it.

Dr. David Jess from the School of Mathematics and Physics at Queen’s University Belfast explains: “For a long time scientists across the globe have predicted that Alfvén waves travel upwards from the solar surface to break in the higher layers, releasing enormous amounts of energy in the form of heat. Over the last decade scientists have been able to prove that the waves exist but until now there was no direct evidence that they had the capability to convert their movement into heat.

“At Queen’s, we have now led a team to detect and pinpoint the heat produced by Alfvén waves in a sunspot. This theory was predicted some 75 years ago but we now have the proof for the very first time. Our research opens up a new window to understanding how this phenomenon could potentially work in other areas such as energy reactors and medical devices.”

The study used advanced high-resolution observations from the Dunn Solar Telescope in New Mexico (USA) alongside complementary observations from NASA’s Solar Dynamics Observatory, to analyse the strongest magnetic fields that appear in sunspots. These sunspots have intense fields similar to modern MRI machines in hospitals and are much bigger than our own planet.

Dr. Samuel Grant from Queen’s comments: “By breaking the sun’s light up into its constituent colours, our international team of researchers were able to examine the behaviour of certain elements from the periodic table within the sun’s atmosphere, including calcium and iron.

“Once these elements had been extracted, intense flashes of light were detected in the image sequences. These intense flashes had all the hallmarks of the Alfvén waves converting their energy into shock waves, in a similar way to a supersonic aircraft creating a boom as it exceeds the speed of sound. The shock waves then ripple through the surrounding plasma, producing extreme heat. Using supercomputers, we were able to analyse the data and show for the first time in history that the Alfvén waves were capable of increasing plasma temperatures violently above their calm background.”