Why is massive star formation quenched in galaxy centers?

November 29, 2017, Instituto de Astrofísica de Canarias
Why is massive star formation quenched in galaxy centers?
Magnetic fields control the collapse of the molecular clouds in the nuclear ring of the galaxy NGC 1097. As a result, formation of massive stars is suppressed in zones of strong magnetic field (contours). Credit: Gabriel Pérez, SMM (IAC)

The current cosmological model to explain the universe, the "Big Bang" model, aims to describe all observable phenomena, including the evolution of galaxies from earliest times to the present day. One of the major problems in the Standard Model is that it predicts a star formation rate that is far too high. All the star-forming material in galaxies should have coalesced into stars when the universe was only a fraction of its present age of 13.8 billion years. However, over half the galaxies we see, mainly spirals, are actively forming stars right now. This discrepancy between theoretical prediction and observation has forced researchers to look much more closely at star formation quenching processes that can slow down the rate of star formation over the lifetimes of galaxies. Without this quenching, the standard Big Bang model fails to predict the universe as we know it.

Researchers have proposed a number of mechanisms for quenching, including "feedback" from supernovae or , which breaks up the star-forming clouds and reduces the rate. Another mechanism has just been reported in Nature Astronomy in a study led by Instituto de Astrofísica de Canarias (IAC) researcher Fatemeh Tabatabaei. The study finds magnetic fields and cosmic rays responsible for the slow formation of massive .

A detailed study of the star formation parameters of the central region of the spiral galaxy NGC 1097 revealed that the presence of a relatively large is acting as a quenching agent, exerting pressure within a gas cloud that can inhibit its tendency to collapse and form stars. The researchers have also shown that this mechanism is, in fact, working around the center of NGC 1097. They combined observations in the visible and the near-infrared from the Hubble Space Telescope with radio observations from the Very Large Array and the Submillimeter Array to explore the effect of turbulence, stellar radiation and magnetic fields on massive star formation in the galaxy's nuclear ring. This ring contains a number of distinct zones where stars are forming inside huge molecular cloud complexes. The principal result they obtained was an inverse relation between the in a given molecular cloud and the magnetic field within it—the larger the field, the slower the star formation rate.

Simulation of star formation in the galaxy NGC1097. Credit: Gabriel Pérez, SMM (IAC).
"To do this, we made a specific separation of the magnetic field and its energy from other sources of energy in the interstellar medium, which are the thermal energy, and the general non-thermal but non-magnetic energy," explains Fatemeh Tabatabaei. "Only by combining the high quality observations at very different wavelengths could we do this and when we separated these energy sources the effect of the magnetic field was surprisingly clear."

Almudena Prieto, another of the authors, says, "Although I have been working on the central zone of NGC 1097 at optical and infrared wavelengths for some time, only when we took into account the magnetic field could we realize its relevance in decreasing the rate at which stars are formed."

This result has several interesting consequences and throws light on several types of interrelated astrophysical puzzles. First, as the magnetic field does not allow very large molecular clouds to collapse and form stars, star formation can occur only after the clouds break up into smaller . This means that this region will have a higher fraction of low-mass stars than in other zones of the galaxy. The tendency of very massive galaxies to contain a high fraction of low-mass stars at their centers is a recent discovery, and is still in some ways controversial, but is reinforced by the work reported here. Also of interest is the fact that the presence of supermassive black holes in the centers of galaxies does tend to enhance the nuclear magnetic , so that this quenching mechanism should be most effective in the bulges of .

Explore further: Image: Hubble's cosmic atlas

More information: F. S Tabatabaei et al, Discovery of massive star formation quenching by non-thermal effects in the centre of NGC 1097, Nature Astronomy (2017). DOI: 10.1038/S41550-017-0298-7

Related Stories

Image: Hubble's cosmic atlas

July 28, 2017

This beautiful clump of glowing gas, dark dust and glittering stars is the spiral galaxy NGC 4248, located about 24 million light-years away in the constellation of Canes Venatici (The Hunting Dogs).

Tune your radio: Galaxies sing when forming stars

February 21, 2017

A team led from the Instituto de Astrofísica de Canarias (IAC) has found the most precise way ever to measure the rate at which stars form in galaxies using their radio emission at 1-10 Gigahertz frequency range.

Understanding star-forming galaxies

June 5, 2017

The more stars a typical spiral galaxy contains, the faster it makes new ones. Astronomers call this relatively tight correlation the "galaxy main sequence." The main sequence might be due simply to the fact that galaxies ...

Hubble scopes out a galaxy of stellar birth

June 26, 2017

This image displays a galaxy known as ESO 486-21 (with several other background galaxies and foreground stars visible in the field as well). ESO 486-21 is a spiral galaxy—albeit with a somewhat irregular and ill-defined ...

A&A special issue: The VLA-COSMOS 3 GHz large project

June 13, 2017

Astronomy & Astrophysics is publishing a series of six articles presenting the results of the VLA-COSMOS 3 GHz Large Project. Led by researchers at the University of Zagreb, the team used the Karl G. Jansky Very Large Array ...

Recommended for you

Nano-droplets are the key to controlling membrane formation

February 19, 2019

The creation of membranes is of enormous importance in biology, but also in many chemical applications developed by humans. These membranes are shaped spontaneously when soap-like molecules in water join together. Researchers ...

LOFAR radio telescope reveals secrets of solar storms

February 19, 2019

An international team of scientists led by a researcher from Trinity College Dublin and University of Helsinki announced a major discovery on the very nature of solar storms in the journal Nature Astronomy.

Pottery reveals America's first social media networks

February 19, 2019

Long before Snapchat, Instagram, Facebook and even MySpace, early Mississippian Mound cultures in America's southern Appalachian Mountains shared artistic trends and technologies across regional networks that functioned in ...

Observation of quantized heating in quantum matter

February 19, 2019

Shaking a physical system typically heats it up, in the sense that the system continuously absorbs energy. When considering a circular shaking pattern, the amount of energy that is absorbed can potentially depend on the orientation ...

Lobster's underbelly is as tough as industrial rubber

February 19, 2019

Flip a lobster on its back, and you'll see that the underside of its tail is split in segments connected by a translucent membrane that appears rather vulnerable when compared with the armor-like carapace that shields the ...

3 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Chris_Reeve
Nov 29, 2017
This comment has been removed by a moderator.
Tuxford
1 / 5 (5) Nov 29, 2017
The tendency of very massive galaxies to contain a high fraction of low-mass stars at their centers is a recent discovery, and is still in some ways controversial...The tendency of very massive galaxies to contain a high fraction of low-mass stars at their centers is a recent discovery../

And this is a questionable patch presented by the maniacs in light of:
https://phys.org/...axy.html
But it is only a pacifier, that many will defend. (Watch)
Small gas clouds remaining quiescent enough to condense into stars near the supermassive core, where massive winds are often blowing outward?? Want to buy a bridge? I have a very pretty one, painted nice and black, so you can't actually see it. But is there, I promise! Believe me...
ursiny33
1 / 5 (1) Nov 29, 2017
If there are large outside magnetic fields around and penetrating the hydrogen gas cloulds it disrupts the small scale magnetic bonding of atoms to each other in their composition of their dominant charge make up like an iron atomis a dominant negative charge and can attract many hydrogen atoms to bond to it magnetically from their dominant positive charge

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

Click here to reset your password.
Sign in to get notified via email when new comments are made.