Gas Outflow From Sculptor Galaxy (NGC 253) Hints At Scarcity Of High Mass Galaxies

This comparison picture of the nearby bright spiral galaxy NGC 253, also known as the Sculptor Galaxy, shows the infrared view from ESO’s VISTA Telescope (left) and a detailed new view of the cool gas outflows at millimetre wavelengths from ALMA (right).
Credit:ESO/ALMA (ESO/NAOJ/NRAO)/J. Emerson/VISTA

The Atacama Large Millimeter/submillimeter Array (ALMA) have observed massive molecular gas outflows ejected by the Sculptor Galaxy (NGC 253). This may explain how starburst galaxies behave and why there is a scarcity of very massive galaxies in the Universe.

Starburst galaxies are galaxies that have a very high rate of star formation compared to regular galaxies. They produce stars so fast that their available gas content is depleted in a shorter time span. Starburst galaxies like the Sculptor Galaxy are defined by the rate at which they convert gas into stars, the available quantity of gas available, and the timescale on which SFR (star formation rate) will consume the available gas with the age or rotation period of the galaxy.

With the available data supplied by ALMA, scientist can study and explain why there are so few massive galaxies around. And if the ejected gas theory holds true for most of these galaxies, they also want to find out what ultimately happens to to these gas outflows.

Starburst Galaxies Effect Far Into The Universe Than Initially Believed

Astronomers using the NASA/ESA Hubble Space Telescope have shown for the first time that bursts of star formation have a major impact far beyond the boundaries of their host galaxy. These energetic events can affect galactic gas at distances of up to twenty times greater than the visible size of the galaxy — altering how the galaxy evolves, and how matter and energy is spread throughout the Universe.

Scientists observing 20 galaxies undergoing a starburst noted that they have an ionizing effect on gases as far as 650,000 light years from its center. Ionized gas is a gas that have lost one or more electrons. In a starburst, the electrons are lost when energetic winds from the starburst excites the galactic gas and knocks the electrons out of the atoms within.

A galaxy that is experiencing a very high rate of stars being formed within it is known as a starburst galaxy. Within a starburst galaxy, the rate of star formation is so high that the galaxy consumes all of its gas. They are known as starbursts because of the frantic episodes of activity when stars are formed.

The burst is triggered by certain events such as being in close proximity with another galaxy, colliding with another galaxy, or by a process where interstellar material is forced into the center of the galaxy. Most stars formed in a starburst burn very bright and very fast. They are likely candidates to explode into a supernova at the end of its life cycle.