Black holes from small galaxies might emit gamma rays

Black holes from small galaxies might emit gamma rays
Blazars launch jets from the black holes at their centers. Credit: Wikimedia Commons

As a general rule of thumb, if there is a puzzling phenomenon occurring somewhere deep in outer space, a black hole is often the culprit behind it.

This is according to postdoctoral researcher Vaidehi Paliya in the department of physics and astronomy, whose January 2018 publication in The Astrophysical Journal Letters details the discovery of seven that could potentially shake up what astrophysicists thought they knew about how the size of a galaxy - and the black hole at its center - can affect its behavior.

It has been widely believed that only contain enough energy to become blazars, which are stupendous jets of radiation powerful enough to stretch thousands of light years. But Paliya's latest research might indicate that smaller galaxies can also do this, if the conditions are right.

There are three main types of galaxies: oval-shaped ellipticals, disk-like spirals and irregulars that don't quite fit in with either of the former classes.

"Elliptical galaxies are the oldest, most massive galaxies in the universe," Paliya said. "People propose that form when two smaller galaxies collide, merging into one big elliptical. Typically, ellipticals are found to host a black hole that is more than a billion times the mass of our sun."

Through their inherent, inescapable gravitational force, at the center of galaxies will grow larger by drawing in and "eating" the surrounding matter through a process called accretion.

"It's like when you pour water in the kitchen sink, you see it forms a spiral, then it goes down the drain. In a similar way, matter forms an accretion disk around the black hole," Paliya said. "The black hole then grows rapidly and becomes a monster."

But when the accretion disk surrounding the black hole begins emitting extreme bursts of energy - in radio, infrared or X-ray bands - the galaxy is said to be "active," opening the door to another galaxy classifier beyond shape.

"Blazars are one type of active galaxy," said Marco Ajello, a professor of physics and astronomy and Paliya's advisor. "These are galaxies that host a supermassive black hole, and this black hole - in some way - is able to accelerate particles to near the speed of light and keep them collimated in narrow beams, called jets, which become very bright sources of light when they are pointing toward us."

These jets are some of the most extreme sources of gamma-ray radiation in outer space.

"These blazars have jets that are like fountains. If you wanted a huge fountain, you'd need to have a very powerful engine at the base. Blazars need to have very massive black holes at their centers to be able to launch jets," Paliya said. "Generally, we don't expect these powerful jets from sources that are small, like our galaxy."

The Milky Way is a spiral galaxy with pinwheel-like arms made up of gas and dust that contain a bright center of older stars. Typically, spiral galaxies are less massive and much less active than their elliptical counterparts.

When the Fermi Gamma-Ray Space Telescope, launched in 2008 by NASA, detected gamma ray emission from four spiral galaxies in its first year of orbit, physicists were perplexed.

"It was unexpected - we have only seen that kind of gamma ray emission from blazars," said Dieter Hartmann, a professor of physics and astronomy and co-author of the study. "When these four sources were discovered, people speculated that they could be blazars. But since there were so few sources, nobody was certain about it. Then the question became: are these really a new type of source, or are they just exceptions to the standard?"

The question was left up in the air, until Paliya's collaborators in India released a catalog of active spiral galaxies in 2017. Known as Seyfert galaxies, these are another type of active galaxy with relatively low mass black holes residing at their centers. However, rather than emitting violent bursts of gamma-ray radiation, like blazars, Seyfert galaxies are known for their strong ultra-violet emissions.

The catalog provided the first chance for astrophysicists to address the question of the Fermi telescope's 2008 discovery. Is it possible for a spiral galaxy to emit jetted gamma-ray radiation?

"I took this catalog of 11,101 Seyfert galaxies, and I studied them in the gamma ray band using the data from the Large Area Telescope onboard Fermi satellite," Paliya said. "From that, I found four new gamma ray sources and three that were earlier known as blazars but we believe are actually Seyfert galaxies."

This breakthrough is an indication that even smaller sources are capable of launching powerful gamma ray jets - a potential paradigm shift in the field of astrophysics.

"If the jet is similar to that of blazars, but its black hole is small, you can imagine it like a car. Say a smaller car is going the same speed as another car that has a much bigger engine. The engine in the smaller car would then need to be much more efficient," Ajello said. "So, it could be that the black hole is working more efficiently in smaller, spiral systems than it is in larger objects like blazars."

To understand the elliptical/spiral nature of the host galaxies of these seven gamma-ray detected sources, Ajello and Paliya intend to obtain deep images with the highest resolution - a challenge for ground-based optical telescopes due to the blurring effects of the atmosphere.

"The light-collecting power of a telescope is proportional to the square of its diameter. This means that with bigger telescopes, we can collect a lot more photons. More photons mean more information," Paliya said.

The Gran Telescopio Canarias, or the "Great Canary Telescope," is a 10.4-meter reflecting telescope that began gathering observations in 2007. Currently holding the title of the "world's largest single-aperture optical telescope," the Gran Telescopio Canarias is slated to be surpassed in the next decade with the unveiling of the Thirty Meter Telescope (TMT). When finished, TMT will have a 30-meter primary mirror and will allow researchers to see outer space with unprecedented clarity - at least 10 times better than the Hubble Space Telescope.

Ajello and Paliya intend to use the Hubble Space Telescope, and potentially upcoming facilities like TMT, to peer beyond the bright centers of the seven sources they uncovered to distinguish with certainty whether the galaxies are elliptical or spiral.

"If it is an elliptical, then it's true that we are just looking at a normal . It's probably a smaller elliptical and a smaller black hole," Ajello said. "But if it's a spiral, then the jets can happen in any environment that is a black hole, within some newfound conditions."

"It is of great importance to better understand the environments of super-massive black holes that are able to launch jets in which particle acceleration takes place under extreme astrophysical conditions," Hartmann added.

Paliya also intends to study whether the differences observed in translate across the electromagnetic spectrum.

"This is all about optics," Paliya said. "How do blazars behave at, say, radio frequencies? Then, how do these Seyferts compare? This discovery has indicated that yes, something different is occurring."

The researchers said that discoveries such as these are important in helping us understand the evolution of the universe. These discoveries could represent some of the missing pieces of the puzzle of how galaxies and black holes have grown together throughout history.


Explore further

Fermi Gamma-ray Space Telescope discovers the most extreme blazars yet

More information: Vaidehi S. Paliya et al, Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies in the Sloan Digital Sky Survey, The Astrophysical Journal (2018). DOI: 10.3847/2041-8213/aaa5ab
Provided by Clemson University
Citation: Black holes from small galaxies might emit gamma rays (2018, February 28) retrieved 22 July 2019 from https://phys.org/news/2018-02-black-holes-small-galaxies-emit.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
360 shares

Feedback to editors

User comments

Feb 28, 2018
As a general rule of thumb, if there is a puzzling phenomenon occurring somewhere deep in outer space, a black hole is often the culprit behind it.

The black hole did it! The dark matter did it! The unseen, undetectable, magic monsters or magic faerie dust did it!

Feb 28, 2018
As a general rule of thumb, if there is a puzzling phenomenon occurring somewhere deep in outer space, a black hole is often the culprit behind it.

The black hole did it! The dark matter did it! The unseen, undetectable, magic monsters or magic faerie dust did it!


Like your invisible, impossible current to power the non-existent non-electric sun? Or the invisible rock and electric discharges at non-electric comets? The evidence for BHs is overwhelming, and likely to be beyond question soon, when the EHT release their findings. Dark matter can be detected through its lensing effects.

Mar 01, 2018
The evidence for BHs is overwhelming, and likely to be beyond question soon, when the EHT release their findings.

LOL, the acolyte is waiting with baited breath for his high priests to manipulate the data to match his fanciful faerie tales.
Dark matter can be detected through its lensing effects.

Funny, electric currents are detected via the magnetic fields which they create. Magnetic fields are everywhere, so too must there be electric currents everywhere to create them. Your inability to process basic facts yet still grasp at faerie dust just shows your religious belief of your pseudoscientific claptrap.

Mar 01, 2018

Funny, electric currents are detected via the magnetic fields which they create. Magnetic fields are everywhere, so too must there be electric currents everywhere to create them. Your inability to process basic facts yet still grasp at faerie dust just shows your religious belief of your pseudoscientific claptrap.

I have multiple magnets on my fridge door. Do they all contain electric currents?

Mar 01, 2018
I have multiple magnets on my fridge door. Do they all contain electric currents?

Yep, magnetism is not magic.

Mar 01, 2018
LOL, the acolyte is waiting with baited breath for his high priests to manipulate the data to match his fanciful faerie tales.


Yep, and that shows the mindset of the scientifically illiterate mythologists of the EU cult. No evidence, let alone a viable hypothesis of their own, yet when evidence shows/ will show up their nonsense for what it is, it's all a conspiracy! Would score high on the Crackpot Index, would this one!


Mar 01, 2018
Funny, electric currents are detected via the magnetic fields which they create.


Wrong. Magnetic fields can persist long after the current that created them has disappeared. The best way to look for currents is from synchrottron radiation, or a radio signature. Such as in COBE, WMAP or Planck. Which is why we know that Peratt's PC woo is wrong. And please show where a current has been detected in the solar wind.

Mar 01, 2018
Magnets on your refrigerator are not orbiting your refrigerator ant near light speed, black holes have an environment that the accretion disks are not tranquil environments its high velocity particles in orbit with intense heat andhigh velocity kinetic particle collisions every atom gets its orbiting electrons stripped in this environment and most of them get trapped orbiting the black hole held in orbit by gravity, constructing a magnetic chamber vessel trapping the protons and neutrons in this magnetic orbiting electron chamber between it and the black hole, if to much material the atoms are torn apart in tgis magnetic chamber it creates an over pressure of energetic particles that the black hole can not consume fast enough that over pressure gets blown out at the poles , because the higg velocity spin of the black hole is twisting the electrons in orbit at the poles making a weak spot there in the electron containment vessel around the black hole.

Mar 01, 2018
Its kind of like a gold mining pan the heavier particles the neutrons and protons go closer to the black gole by gravity and the smaller electrons are farther away from the black hole constructed a magnetic containment field like in an partical accelerator .

Mar 01, 2018
I would suspect that those high velocities kinetic collisions turn atoms back into hydrogen atoms from particle mass loss of parts by the time it makes it to the event horizon to be consumed by the black hole and the over abundance of positive proton mass it consumes makes the black hole magnetically grab those orbiting negatively charged electrons into a closer orbit that produces the over pressure in the containment area to produce those jets of positively charged particle ejections to produce a path that can feed the black hole electrons of negatively charged particles to compensate the charge ratios of the black holes mass for its stability in charge

Mar 01, 2018
Magnetic fields can persist long after the current that created them has disappeared.

Of all the moronic statements you have made, this has got to top them all. This is easily tested. Find an electric motor, turn it off and measure the magnetic field it produces. Should be easy enough as according to jonesdumb the magnetic field will "persist long after" the electric current is shut off. Wow, new and astounding levels of stupidity are exceeded everyday!
The best way to look for currents is from synchrottron (sic) radiation, or a radio signature

That is exactly what was found, the plasma ignoramuses just blame it on "primordial" nonsense.

Mar 01, 2018
@CD85:
How much electric current do you measure in your fridge magnets?

Mar 01, 2018
That is exactly what was found, the plasma ignoramuses just blame it on "primordial" nonsense.


No, they didn't. At least not as Peratt predicted. Why do you think it is not taken seriously, and Peratt gave up on it, to go wandering off into the boonies, looking for plasma rock art?
And, as I said, where is the current in the solar wind? It carries a magnetic field.

Mar 02, 2018
@CD85:
How much electric current do you measure in your fridge magnets?


@ 691boat The real question is how was your fridge magnet created?

Mar 02, 2018
Lodestones are Earth's original and naturally occuring magnet. How do lodestones get magnetized?

"The Earth's magnetic field at 0.5 gauss is too weak to magnetize a lodestone by itself. The leading theory is that lodestones are magnetized by the strong magnetic fields surrounding lightning bolts. This is supported by the observation that they are mostly found near the surface of the Earth, rather than buried at great depth." ---Wikipedia

Mar 02, 2018
@ 691boat The real question is how was your fridge magnet created?


Thank you for making my point for me, as posted above; therefore detection of a magnetic field does NOT automatically mean we are detecting an electric current. As we see in the solar wind. Maybe you should explain that to cd, rather than 691?

Mar 02, 2018
@ 691boat The real question is how was your fridge magnet created?


Can't say I recall the last lightning strike to my fridge to keep that magnetic field going...

Mar 05, 2018

Thank you for making my point for me, as posted above; therefore detection of a magnetic field does NOT automatically mean we are detecting an electric current. As we see in the solar wind. Maybe you should explain that to cd, rather than 691?

So you are suggesting plasma is ferromagnetic? Fraid not snookems.

Mar 05, 2018

Thank you for making my point for me, as posted above; therefore detection of a magnetic field does NOT automatically mean we are detecting an electric current. As we see in the solar wind. Maybe you should explain that to cd, rather than 691?

So you are suggesting plasma is ferromagnetic? Fraid not snookems.

No, but you constantly imply that magnetic fields only exist where an electric current is present. i.e. the sun has a large magnetic field, therefore, according to you, it has a huge electric current associated with it.

Mar 06, 2018
Ummmm, yeah. That is correct, but it's not according to me. See Maxwell's equations and relevant EE concepts.
Earth has the electric Birkeland currents and a large magnetic field as well, it is what creates Earth's fields.

Mar 06, 2018
Ummmm, yeah. That is correct, but it's not according to me. See Maxwell's equations and relevant EE concepts.
Earth has the electric Birkeland currents and a large magnetic field as well, it is what creates Earth's fields.


Not even wrong! Surely you aren't serious? Or have you just phrased something poorly?
The magnetic field is due to the dynamo action of the core. The magnetic field is apparent at the surface. Compasses would be useless, otherwise. So, what is the current measured at the Earth's surface? Birkeland currents are merely an induced consequence of the interaction of the solar wind IMF with the Earth's magnetic field. If Venus had an intrinsic magnetic field, we would see the same effect there. We don't. It is much more akin to the SW/ IMF interaction with comets. Ditto Mars.

Mar 06, 2018
The magnetic field is due to the dynamo action of the core.

That's the claim, doesn't mean it is a fact.
Compasses would be useless, otherwise.

That is just a hand wavy claim by you, no basis to falsify the BC model.

Mar 06, 2018
The magnetic field is due to the dynamo action of the core.

That's the claim, doesn't mean it is a fact.
Compasses would be useless, otherwise.

That is just a hand wavy claim by you, no basis to falsify the BC model.


Lol, you WERE serious! Deary me. Even Birkeland would tell you that you are horribly wrong.

Mar 06, 2018
@CD85:
Let me guess: the poles reversing in Earth's magnetic field is because the inter-solar currents changed direction, meaning the sun used to be a sink instead of a source?

Mar 06, 2018
Are there really serious questions asking why we there's no detectable current in a permanent magnet? You are all hopefully aware of an atom's magnetic moment, and how it's created right?

Mar 06, 2018
Are there really serious questions asking why we there's no detectable current in a permanent magnet? You are all hopefully aware of an atom's magnetic moment, and how it's created right?

Im only seriously asking it from cd who claimed that there's an electric current everywhere where magnetic fields are present.

Mar 06, 2018
Are there really serious questions asking why we there's no detectable current in a permanent magnet? You are all hopefully aware of an atom's magnetic moment, and how it's created right?

Im only seriously asking it from cd who claimed that there's an electric current everywhere where magnetic fields are present.

Please keep this in context, we are ultimately discussing space plasmas.
http://electric-c...OAAJ.pdf
Let me guess: the poles reversing in Earth's magnetic field is because the inter-solar currents changed direction, meaning the sun used to be a sink instead of a source?

Already pointed out how you should stop guessing, anyways read the paper I linked to as it has a section on pole flipping fields.

Mar 06, 2018
@CD85:
so, where are those amazing currents going INTO the poles of the sun? right....never seen or measured them.
also, you pole flipping is based on a time flux? So you are saying that the current(s) passing through earth have a variable characteristic to them, like alternating current, but at a frequency of ~6.3x10^-13 Hz, assuming pole reversals every 200,000 years? That's pretty nifty. Why doesn't Mars have a magnetic field anymore? Is the current passing through it still in a decreasing magnetic flux condition?

Mar 06, 2018
@cantdrive85.
Earth has the electric Birkeland currents and a large magnetic field as well, it is what creates Earth's fields.
How do you explain the observation that planets/bodies that do not spin, or that have no 'core',layers rotating differentially, have generate no planetary/body magnetic field, mate?

PS to all 'sides': It's time all 'sides' started to review their longstanding 'claims', to actually check with the reality that which may be tenable now and those which may not be tenable now. Maybe then you will all be working off the same page and not still feuding due to 'old' misunderstandings and 'one-eyed' perspectives of the 'hybrid forces phenomena' reality involving moving charges and gravitational/inertial/electro-magnetic 'charge-sorting' dynamics at geophysical/astrophysical scales creating/evolving 'features' and 'flows' over large/long spatial/temporal extents/circuits. Good luck all. :)

Mar 06, 2018
@cantdrive85.
Earth has the electric Birkeland currents and a large magnetic field as well, it is what creates Earth's fields.
How do you explain the observation that planets/bodies that do not spin, or that have no 'core' layers rotating differentially, have no 'overall dipolar' planetary/body magnetic field, cd?

PS to all 'sides': It's time all 'sides' started to review their longstanding 'claims', to actually check with the reality that which may be tenable now and those which may not be tenable now. Maybe then you will all be working off the same page and not still feuding due to 'old' misunderstandings and 'one-eyed' perspectives of the 'hybrid forces phenomena' reality involving moving charges and gravitational/inertial/electro-magnetic 'charge-sorting' dynamics at geophysical/astrophysical scales creating/evolving 'features' and 'flows' over large/long spatial/temporal extents/circuits. Good luck all. :)

Mar 06, 2018
@CD85: giving your theory further thought, If Earth's magnetic field was indeed caused by currents from the sun, then that would imply that every planet or object in the "circuit" would have the same pole reversals, correct? But.... as far as I know, the Earth and Sun don't swap poles together, as would be expected by EU. Further more, since the planets are not in a straight line with each other relative to the Sun, why don't we see big explosive events all the time whenever planet orbitals cross one another? Seems like there would be currents joining and breaking pretty frequently in just our solar system alone, per your explosive circuit theory.

Mar 06, 2018
Already pointed out how you should stop guessing, anyways read the paper I linked to as it has a section on pole flipping fields.


That is a bunch of crap by the idiot Scott. Why on Earth would anybody take it seriously?

Mar 06, 2018
How do you explain the observation that planets/bodies that do not spin, or that have no 'core' layers rotating differentially, have no 'overall dipolar' planetary/body magnetic field, cd?

The potential difference from it's surroundings is not as significant, and the Earth has a great deal of water for EMF.

Mar 06, 2018
That is a bunch of crap by the idiot Scott.

https://youtu.be/2TnkJ8_BmSI
Surprise, surprise, surprise!
Why on Earth would anybody take it seriously?

For the same reasons people should take Maxwell, Birkeland, Langmuir, Alfvén, Bruce, and others seriously, because he uses the very same EE principles and physics those scientists did.

Mar 07, 2018
For the same reasons people should take Maxwell, Birkeland, Langmuir, Alfvén, Bruce, and others seriously, because he uses the very same EE principles and physics those scientists did.


None of whom thought that the Earth's magnetic field was due to Birkeland currents! As far as I can tell, you are the only person on the planet that believes such a thing.


Mar 07, 2018
CD85:
Again, why doesn't Earth's magnetic pole swap every sun cycle (i.e. every 9-14 years)?

Mar 07, 2018
CD85:
Again, why doesn't Earth's magnetic pole swap every sun cycle (i.e. every 9-14 years)?


Ahhh, jeez mate - that would involve actually having to think about stuff (i.e. science), and then coming up with a viable hypothesis. In the rather turgid history of EU, that has never happened. So, I'm guessing that your question was rhetorical. Yes? :)

Mar 07, 2018
What's really going to be interesting is when someone works out the mechanics of the solar dynamo that causes the sunspot cycles. I'm speculating here, but that's what I think we'll eventually find.

Mar 07, 2018
CD85:
Again, why doesn't Earth's magnetic pole swap every sun cycle (i.e. every 9-14 years)?

Why would it?

Mar 07, 2018
Why would it?
For the same reasons you cited.

Maybe you forgot.

Mar 07, 2018
I never suggested it, boat had an epiphany and though his idea was valid. He raises a red-herring, if you actual understand the mechanism that is suggested, the current doesn't change direction. The conditions that apply to the Sun obviously are somewhat different than the Earth and they don't apply directly without considering the numerous variables.

Mar 08, 2018
I never suggested it, boat had an epiphany and though his idea was valid. He raises a red-herring, if you actual understand the mechanism that is suggested, the current doesn't change direction. The conditions that apply to the Sun obviously are somewhat different than the Earth and they don't apply directly without considering the numerous variables.

So now the magic currents going into the Sun's poles are completely separate and have absolutely nothing to do with the magic currents coming out via the solar wind? Why would I expect anything else?

Mar 08, 2018
Once again, your "thinking" is getting in your way. Don't be a moron like jonesdumb and exclaim something impossible before even understanding the underlying concepts. It's just lazy.

Mar 08, 2018
Once again, your "thinking" is getting in your way. Don't be a moron like jonesdumb and exclaim something impossible before even understanding the underlying concepts. It's just lazy.


We do understand the underlying woo. That is why it is impossible.

Mar 08, 2018
You clearly don't, that's there is a long list of concepts that require the actual definition, and the jonesdumb "definition".
See electrochemistry vs. "electrochemistry"; "where's the electrolyte?"...
There are so many more examples, kinda like;
"Magnetic fields can persist long after the current that created them has disappeared." jonesdumb

You're a moron plain and simple, you cannot get past the grade school concepts let alone the complex ones. Else you wouldn't say moronic this like;
"There are no electric discharges happening at comets. Full stop."
When we know for a fact electric discharge absolutely occurs at comets.

Mar 08, 2018
@CD85:
I fully understand. Per the link you provided to explain the pole reversals, it said it is due to a magnetic time flux, or a changing in the intensity of the magnetic field due to an increase or decrease in the magnitude of the incoming electric current. Your link says that as the current decreases, this in turn creates a net negative change in the magnetic field, which we see as a pole reversal. Given that, the Sun swaps poles every 9-14 years, but Earth does it only on a scale of every 200,000-300,000 years.
So, since the current coming in to the sun is apparently constantly increasing and decreasing, but very repeatably and cyclical, it would mean that the supposed current passing out of the Sun to effect Earth is in no way related to the current passing into the Sun unless the Sun has an internal frequency converter to change the outgoing current to a much longer time period. Therefore, your model fails.
Where am I wrong?

Mar 08, 2018
Magnetic fields can persist long after the current that created them has disappeared


Yep. Where is the current in the solar wind?

See electrochemistry vs. "electrochemistry"; "where's the electrolyte?"...


Because that is the accepted use of 'electrochemistry'. If you're talking about the rubbish proposed by Anariba on Dunderdolts, that fails miserably.

When we know for a fact electric discharge absolutely occurs at comets.


Really? Where?

Mar 08, 2018
Therefore, your model fails.
Where am I wrong?


You aren't. You could have also added the complete lack of detection of any such currents, either inbound or outbound.

Mar 08, 2018
@691Boat (& @cantdrive85).

Sun's 'dipolar' magnetic field can be conveniently treated as generated like in SOLENOID (as sun's internally circulating PLASMA currents form sort of 'helical charge-flow structure' between its poles).

And, as for 'solenoid' (or 'bar') magnet, the EXTERNAL 'B field' strength 'falls off' to 'effectively' ZERO very quickly along radials of 'central perpendicular plane' (ie, sun's 'equatorial perpendicular plane').

Hence sun's MAGNETIC effects impact very little directly on Earth (or Earth's 'dipolar' magnetic field).

So:

- Sun's main (non-gravitational) influence on Earth's own magnetic field comes from SOLAR WIND 'plasma flows' (and any transient/randomly-directed 'fast-electron currents' arising therein);

- so, magnetic POLE REVERSALS are 'effectively' ONLY LOCAL for SUN ITSELF.

Ask yourselves:

Do Sun's 'pole reversals' stop or reverse SOLAR WIND?

Obviously NOT.

So, SW plasma/fast-electron flows/currents 'continue as usual'! :)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more