Powehi: More than a fuzzy orange ring!
10th April 2019- For the very first time in human history,a picture of the Gargantuan beast, super massive black hole “Powehi” was captured dwelling at the heart of Messier 87 galaxy. Einstein’s very own “Schwarzchild singularity”, better known as “Black hole” jumped out of text books and landed into the lens of The Event Horizon Telescope placed 50 million light years away. The devil is expected to be huge enough to fit 6.5 billion suns in it and swallows everything from stars, planets to even light that comes in its way.
Though the picture looks blurred and pretty much out of shape, it is approximated that the data obtained from this image is equal to that of 40,000 selfies taken by a person in their lifetime and is marked as a huge leap as far as Astrophysics is concerned.
The beast was named “Powehi” which in Hawaiian means “embellished dark source of unending creation” as the black hole was illuminating and brightening the darkness around it.
HOW WAS THE IMAGE OBTAINED?
This huge amount of data for sure cannot be handled by a single satellite and so, The event horizon telescope is a range of 8 different radio telescopes present at various parts of the world, which convert the Earth into a virtual planet size telescope and collect data in parts (by each individual telescope) and then attached to each other for the final image. These telescopes are present at various parts of the world and the photons coming from the black hole are collected in parts in a particular order.
The collected data is arranged and changed according to astronomical predictions due to the difference in time zones of these radio telescopes and then stitched to one another to obtain the final image. Powehi was first discovered in 2017 but it took 2 years time for the scientists to analyze the data coming of it and stitch them accordingly to obtain the final picture.
WHAT DOES THE IMAGE LOOK LIKE ?
When we look at it, what we are actually seeing is the stream of light rays or the “Fuzzy orange ring” around its Event Horizon. Event Horizon is the boundary that limits the size of the black hole. Black holes have a very strong gravitational field and everything including light once traveled into, gets trapped in its Singularity. So, the basic laws of reflection doesn’t work here. i.e, when we look at an object, light around our eyes hit the object and its reflection falls on our retina and we capture it.
But here, there is no chance of reflection as light that enters the black hole doesn’t come back. So a deeper look at the image suggests that the glowing orange ring visible is the Event horizon and huge cluster of light rings surrounding the black hole due to its gravity.
Therefore, as depicted by Einstein in his general theory of relativity, the image of a black hole would look like an eye of a person, known as the Silhouette of black hole or the Einstein’s Eye. The dark spot at the center is the shadow cast by the light known as the black hole shadow. in simple terms, this picture marks as a proof for Einstein’s general theory of relativity.
WHAT CAN WE UNDERSTAND FROM THE IMAGE ?
The picture when subjected to sharpness, it leads to observe that the fuzzy yellow disk is a combination of stream of light rays. The yellow ring which is observed in the picture is known as Photon sphere which correspond to the number of orbits that photons took around the black hole before reaching the observer.
These sharpened images say that, all the nested rings around the black hole have same thickness but the ones nearer tot he black hole have harp edges than the ones which are far from it. This is because the black holes tend to absorb the photons towards and so the ones which are nearer have to travel larger distances compared to the ones which are nearer to us.
Not only do these images suggest the wrap of space and time, but also do they help to observe how the presence of these celestial bodies do change the way we look at space. For instance, in 2015, scientists discovered the presence of gravitational waves for the first time and these were produced due to collision of two black holes ( happened around 1.3 billion years ago).
These observations obtained from Powehi are expected to be used in further black hole studies as the next step is expected to be towards Sagittarius A* black hole. Though it is at a nearer distance (29,000 light years from Earth), scientists find it tougher to get a picture of it as it is present in the same galaxy.
Relative movement of the black hole and our planet within the same galaxy with 2 billion stars and many celestial bodies in between, scientists expect to get into outer space to capture and understand its working since there would be a lot of debris and obstacles in between causing trouble in capturing the image.
By comparing M87’s relatively active jet with eventual images of our own Sagittarius A*, it is expected to understand the ebb and flow of the influence of black holes in the long course of history of the universe in a much better way.
