volume (6)

September 5th, 2021

Hello Earthlings.

Sorry I left you without a brain-ache and an in the night sky last week.

I was distracted learning how to pilot a spaceship.

While we were gone…

Perseverance’s drill holding its rock core sample(!) on Sol 190, Earth date September 1st, 2021 (Image Credit: NASA/JPL-Caltech/ASU/MSSS)

Percy successfully cored its first sample! We knew you would find that perfect rock. You go bot!!!

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let’s go 

volume (6):

Hubble catches distant quasar thanks to cosmic magnifying glass(!)

What appears to be a ring of dots around a bright spot is actually just one distant celestial object warped by the mass of two galaxies in front of it in Hubble’s field of view (Image Credit: ESA/Hubble & NASA, T. Treu)

Yes. I know. What the f#$% is a quasar please? And what exactly do you mean by cosmic magnifying glass? That sure is a pretty cool picture though(!).

A quasar is scholarly defined as a “quasi-stellar-radio-object”. Quasars are so bright, they outshine the galaxy from which they originate (especially in radio wavelengths). In the first radio sky surveys in the 1950’s some of the radio sources in the images appeared star-like to the observers. So they were named “quasi-stellar-radio-objects”, which was then shorthanded to quasar. I swear I was taught that a quasar was a f#$%ing star when I was in school and I’m not that old (my astrophysics teacher was, though). Because it always seems that we learn new things faster than we can historically rename them, these so-called “quasi-stellar-radio-objects” are still referred to as such. If you ask me, the term is just misleading. It’s probably more like a step in the life cycle of black holes. They are definitely not genuine stars. I can see the argument for calling a black hole a stellar-object, but I still don’t think its helpful to think about it that way. Maybe you can call it the quasar phase(?) of a black hole.

Quasar 3C 273 lives 1.9 billion light-years away in the constellation Virgo. As imaged by Hubble in 1994 (Image Credit: NASA and J. Bahcall (IAS))

Have we talked about black holes yet? Not entirely, no. You might remember from volume (2) that black holes can represent the end of some (massive) star’s life cycles. Black holes can also be formed by the meeting and combining of two (very massive) stars in their lifetimes. One of Hawking’s famous musings involves so-called primordial black holes - effective seedling micro black holes from the early universe that have grown as they have eaten space matter for billions of years. A black hole is a celestial object which is so massive, it bends the fabric of space-time so intensely, that the velocity required to escape its gravitational pull exceeds the speed of light (AKA the cosmic speed limit of the Universe). All black holes have what is called an event horizon, which is the point of no return; once you cross the event horizon of a black hole you cannot escape its gravity. As the mass of a black hole grows, so too does its event horizon (think about literally a bigger and bigger hole opening).

Just like stars, black holes vary in mass. To date, there are five flavors of black holes:

1. primordial (micro) black holes; about the mass of our moon, would have existed in the early universe may still be traversing space somewhere yet discovered

2. stellar black holes; up to about 10x the mass of our sun, these are the kinds formed by - you guessed it- dying stars

3. intermediate-mass black holes; up to about 10,000x the mass of our sun, a relatively newly observed phenomena these mythical sized black holes were not thought possible maybe five years ago, these black holes are in all likelihood formed from the collisions/mergers of other smaller black holes

4. supermassive black holes; up to about 1 million times the mass of our sun, usually found in the centers of large galaxies “old” and “new”, definitely formed from merging and also many many many many years of feasting

5. ultra massive black holes; up to about 1 billion times the mass of our sun, these absolutely ginormous monsters found at the centers of some distant galaxies are almost certainly the result of the combination of two or more supermassive black holes

Active Galaxy Hercules A lives 1.9 billion light-years away in the constellation Hercules. Here shown in x-ray (pinky purple), optical (whiteish) and radio (blue) wavelengths. In just visible light Hercules A appears to be a typical elliptical galaxy. In X-ray light, however, Chandra detects a giant cloud of multimillion-degree gas. This gas has been heated by energy generated by the infall of matter into a central black hole 1,000 times as massive as SGR A* of the Milky Way. Radio data show jets (which span almost one million light-years!) of particles streaming away from the black hole. (Image Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA)

All of these black holes are everywhere, all across the universe, and even in our galaxy. The Milky Way’s supermassive black hole (scholarly known as Sagittarius A* or SGR A*) at its center, might be the one you’ve heard of. There are plenty more roaming around the galaxy as we speak. Remember the black hole binary V404 Cygni from volume (3)? Tons of other stars are currently orbiting companions with black holes, destined to be destroyed after a (relatively) slow process of being gobbled by their hungry travel partners. Black holes can orbit each other too, two black holes in a binary system will eventually merge together to make an newly massive black hole.

This visualization shows a complete 360 view around a simulated black hole and its accretion disk following a path that is perpendicular to the disk. The black hole’s extreme gravity redirects and distorts light coming from different parts of the disk, but exactly what we see depends on our angle of view. (Visualization Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman)

Just like stars, black holes go through phases, and they are dependent on their mass. So far these are loosely described as active and dormant. Very helpful I know. Just as more massive stars move through their life cycles more quickly than less massive stars, the more massive the black hole the faster it moves through its active phase. According to observations of the present universe, about 10% of all galaxies (or all galaxies 10% of the time) appear to be active. The term active is used to describe galaxies with unusual spectral line emission and very strong radio emissions. Within this class of Active Galactic Nuclei (AGN) (or Active Galaxies) there are a few types arranged in a hierarchy of how much they emit in radio wavelengths. There are the so-called Radio Galaxies at the lowest on the radio totem pole, whose brightness is nothing compared to the Quasars - the most luminous sources in the universe. They are also very far away. The closest quasar (galaxy) of the million discovered to date is oh just a mere 581 million light years from here(!).

Markarian 231, the closest known “quasar” to the Milky Way lives 581 million light-years away in the constellation Ursa Major.(Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University))

It should be mentioned that perhaps even more so than stars, black holes are constantly changing due to their hungry nature. I mentioned that their phases are dependent on their mass, and black holes are categorically feasting beings, constantly gaining more mass. Even our SGR A* displays indications of more active nature than previous records - probably due to a close encounter (AKA a small feast) with a star whose orbit brought it too close to the supermassive black hole. Then it will calm down again and resume its usual more dormant nature. But when it comes to a black hole’s quasar phase it’s all about the dust and gas baby - it always is isn’t it!!!

A detailed depiction explaining just what we could “see” from a black hole (Image Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman)

I should clarify at this point, that what is so bright about this black hole in its quasar phase is not the black hole itself but rather its accretion disk. It is the result of the processes taking place at the very edges of the giant hole in space-time; at the event horizon. Remember how stars were formed of gas and dust accreting onto the baby stars? Same here, but with extreme dynamics at play due to the immense gravity of black holes. Black hole accretion disks are formed because of one the the laws of motion - the conservation of angular momentum. Because the black hole cannot just directly pull the matter in a straight line into its singularity, the gas appears to settle in a disk as it swirls its way past/into the event horizon. The accretion disk of a black hole is hot enough to emit x-rays just outside the event horizon. The luminosity of quasars is believed to be a result of gas being accreted by supermassive black holes. These black hole accretion processes can convert 10-40% of the mass of any object into energy (a genuine star’s nuclear fusion processes only convert about 0.7%!). They are the most energetic sources in the known universe. Wow.

The gigantor elliptical galaxy M87 is the home of several trillion stars, a supermassive black hole, and a family of 15,000 globular star clusters. If you look closely you can see the jet of subatomic particles accelerating away from the central black hole. M87 lives 54 million light-years away in the constellation Virgo. (Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgment: P. Cote (Herzberg Institute of Astrophysics) and E. Baltz (Stanford University))

So what about our Milky Way’s supermassive black hole?(!) Will it turn quasar on us and eat up all the galactic dust and gas and hinder star birth and outshine all the rest of us for any aliens looking our way? The truth is nobody is sure. The Milky Way is thought to have already experienced its active phase of life. The Milky Way is likewise due to have a run in with the Andromeda Galaxy (which is also in its dormant phase) in about 4 billion years. Did you know that the Andromeda Galaxy is falling towards the Milky Way at a rate of 68 miles per second? Galactic collisions, especially those with supermassive black holes involved, are known to reignite all sorts of “dead” systems. The whole life cycles of the galaxy can begin again.

Oh yeah, wait, what ever happened to the cosmic magnifying glass making us see quintuple of these cosmic mysteries?

Galaxy Cluster Abell 370 is located about 4 billion light-years away in the constellation Cetus. In a combination of visible and near-infrared light, the immense cluster is a rich mix of galaxy shapes. The brightest and largest galaxies in the cluster are the yellow-white, elliptical galaxies containing many hundreds of billions of stars apiece. Spiral galaxies - like our Milky Way - have younger populations of stars and appear bluish. Dispersed throughout are what look like blueish arcs across the sky; these are hundreds of galaxies even farther away whose light is distorted on its way through space by the sheer gravitational pull from this cluster allowing Hubble to observe ever deeper into the universe. (Image Credit: NASA, ESA, and J. Lotz and the HFF Team (STScI))

Glossing right on over to… everything in the universe has mass, even light(!). So when light travels through the universe it sometimes gets distorted on its way to us. In the example of the Hubble image at the start of this adventure, there are two galaxies directly in front of the quasar source from our earthly POV. These galaxies have astronomical masses (and therefore astronomical gravitational pull) that bend and curve the light from behind them as it passes by continuing through space until it reaches Hubble. This is called gravitational lensing. Gravitational lensing is really cool because oftentimes they act like naturally occurring zooms into the past, allowing telescopes to see deeper into cosmic history than they would otherwise be capable of.

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It’s a plane, its a star, no it’s Jupiter and Saturn (!)

Jupiter (left) and Saturn (right) shining bright in the twilighty sky (Thursday September 2nd, 2021 8:22pm pacific Earth time)

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Don’t Miss Out (!)

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“Nothing happens until something moves. When something vibrates, the electrons of the entire universe resonate with it. Everything is connected.” - Albert Einstein

This has been space matter(s). 

See you in the starstuff.

-RRR