X-Rays from Milky Way’s Supermassive Black Hole

Most of us are aware of harmful radiation from our sun but don't realize that the Milky Way’s Supermassive Black Hole called Sagittarius A* (shortened to Sgr A) has enough energy to cause damage to life on earth. Although Sgr A is about the size of size of the Earth's orbit around the Sun and some 26,000 light years away from earth, its immense mass, some 4 million times the mass of the Sun, allows it to swallow stars for breakfast causing massive outbursts of energy, These energy outbursts have been estimated to at least as powerful as the suns from our perspective on earth.



Recently a cloud called G2 orbited a bit too close to Sgr A resulting in the largest ever flares detected from Sgr A and a ten-fold increase in the rate of bright flares (now one every day). The G2 cloud survived its closest approach to Sgr A in 2014 but the flares still continue today.

The so-called "megaflare" flare was spotted by NASA's Chandra X-ray Observatory, which can peer through dust and starlight to the centre of the Milky Way. The event was 400 times brighter than the normal level of radiation from this region and nearly three times brighter than the previous record-holding flare, recorded in 2012. A second X-ray flare, with a flash 200 times brighter than normal levels, was then seen on Oct. 22, 2014.
Link

Because the increased rate of flares from SigA continues today its been suggested that G2 may have been a star, surrounded by a cloud of gas, and the spike in X-rays is a result of excess material still falling into the black hole. We might witness increased activity in coming months.

"The G2 cloud survived its closest approach to Sgr A in 2014..."

Give or take 26000 years.

Interesting post. Thanks!

The Sun is a poor emitter in X-rays; most of the threat from it is in form of the streams of charged particles, as well as its UV radiation. Therefore, I wouldn't place much weight into comparing the radiation from Milky Way's BH with our Sun, in terms of possible damage from X-rays.

originally posted by: wildespace
The Sun is a poor emitter in X-rays; most of the threat from it is in form of the streams of charged particles, as well as its UV radiation. Therefore, I wouldn't place much weight into comparing the radiation from Milky Way's BH with our Sun, in terms of possible damage from X-rays.

...And one major source of that stream of charged particles/cosmic rays may be supermassive black holes in active galactic nuclei (supernovae may be another source).

originally posted by: Soylent Green Is People

originally posted by: wildespace
The Sun is a poor emitter in X-rays; most of the threat from it is in form of the streams of charged particles, as well as its UV radiation. Therefore, I wouldn't place much weight into comparing the radiation from Milky Way's BH with our Sun, in terms of possible damage from X-rays.

...And one major source of that stream of charged particles/cosmic rays may be supermassive black holes in active galactic nuclei (supernovae may be another source).

Ok, but the OP focuses on X-ray radiation. The linked paper says that "in both cases Sagittarius A* could precipitate on Earth an X-ray (hν>2 keV) irradiance comparable to that from the current quiescent sun."

Interestengly enough, the estimates in the harder part of X-ray range surpass the radiation from the Sun's X-class flares, also giving them a longer time span, which indeed would affect life and environment on Earth in a harmful way.

Cmon if we just think about it for a moment we are already in the black hole at the center of the milky way, and we always have been! We are but projections from the other side of another black hole!

originally posted by: FormOfTheLord
Cmon if we just think about it for a moment we are already in the black hole at the center of the milky way, and we always have been!

I believe you might be a bit confused about spacetime dilation.

Objects inside a black hole would see exterior time accelerate. And someone outside (in the galaxy) would see the black hole object's time slow down until it freezes forever. Inside both frames, time would appear to flow normally.

So no, the existence of black holes does NOT imply that "we are already in the black hole at the center of the milky way, and we always have been"; and, additionally, being inside a black hole would tear you into pieces until you are nothing but a mere cloud of elemental particles.

a reply to: swanne

being inside a black hole would tear you into pieces until you are nothing but a mere cloud of elemental particles.

I have always liked this description of falling into a black hole.



What a horrible way to die.

a reply to: swanne

Don't we see everything outside of our galaxy speeding away from us faster and faster... the cause of this is called black energy ?

So except for the getting torn into pieces, part of the explanation does seem to say we are in or maybe close to a singularity ?

Just asking...

originally posted by: Sinter Klaas
a reply to: swanne

Don't we see everything outside of our galaxy speeding away from us faster and faster... the cause of this is called black energy ?

So except for the getting torn into pieces, part of the explanation does seem to say we are in or maybe close to a singularity ?

If you are inside a strong gravitational field such as the one from a black hole, your personal space and time intervals will be dilated like crazy. This means that for every of your seconds, the outside universe seem to experience thousands and thousands.

If we truly are in a singularity (as so many sensationalist shows like to make the people believe), then it means that not only would galaxies seem to accelerate, but their time will also seem as if they were fast-forwarded. Their stars would go supernova at insane rates, they would visibly degenerate with the passing years, etc - all of these which are contrary to observations.

originally posted by: tsurfer2000h
I have always liked this description of falling into a black hole.

As he says that applies to small black holes, maybe 3 solar masses. It doesn't apply to supermassive black holes of 4 million solar masses, at least not when you first cross the event horizon. You might think the gravity is stronger for 4 million solar masses, and it is, but countering that is the fact that the event horizon is much further away from the center of mass, so the tidal forces are actually lower at the event horizon for more massive black holes.

Another reason you wouldn't die that way falling into the black hole at the center of the milky way is the reason given in this thread OP...the high energy radiation would likely kill you long before tidal forces could pull you apart. Which would kill you first with a smaller black hole might depend on how much matter is falling in and how much radiation it's giving off, your velocity falling in, etc.