How do galaxies die? Contradictions between two papers

In summary, Nova is a researcher who is interested in the life cycle of planets, stars, and galaxies. They posted a question on reddit, but received no response. They were then directed to Physics Forums, where they posed their question about contradictory papers on the death of galaxies. One paper suggests that galaxies die from "strangulation" due to depletion of their fuel source, while the other suggests they die because their fuel is stripped away. Nova believes both could be possible, but more research is needed. Nova also shares their background as an astronomy major and mushroom farmer. They provide two links to the research papers and offer to share the arXiv links as well.
  • #1
Novanglus
4
0
Hi all!
My name is Nova and I have recently started a research project on the life cycle of planets, stars, galaxies, etc. I posted this question on reddit, but no one seemed particularly interested. Someone suggested I consult the ultimate physics community on the web, Physics Forums, so here I am.

These two papers (one published in February, the other, a few days ago) seem to be contradicting each other. One says they will die from "strangulation" because their source of fuel eventually runs out (they measured the average change of metallicity in thousands of galaxies to determine this). The other says they die because their source of fuel is actually stripped away. Am I not understanding something? Can they both be right?
My hunch says both *can* happen, but the latter is much less likely and more research needs to be done.

A bit about myself. I am an astronomy major and a novice shroomer (mushroom farmer, non-psychadelic).
Thanks so much
Nova

1.) May: http://phys.org/news/2015-05-galactic-death-strangulation.html

2.) February: http://phys.org/news/2015-02-fast-die-young-galaxies-gas.html#nRlv

P.S. Let me know if you need me to link to the research papers themselves.
 
Astronomy news on Phys.org
  • #2
Welcome! I'm glad to see you--this is an interesting question and it seems as yet unresolved. You could give us the arXiv links to the professional grade papers. I'm not an expert but I like to see what the authors actually said.

One is here:
http://arxiv.org/abs/1501.07653
Misalignment between cold gas and stellar components in early-type galaxies
O. Ivy Wong, K. Schawinski, G.I.G. Józsa, C.M. Urry, C.J. Lintott, B.D. Simmons, S. Kaviraj, K.L. Masters
(Submitted on 30 Jan 2015)
Recent work suggests blue ellipticals form in mergers and migrate quickly from the blue cloud of star-forming galaxies to the red sequence of passively evolving galaxies, perhaps as a result of black hole feedback. Such rapid reddening of stellar populations implies that large gas reservoirs in the pre-merger star-forming pair must be depleted on short time scales. Here we present pilot observations of atomic hydrogen gas in four blue early-type galaxies that reveal increasing spatial offsets between the gas reservoirs and the stellar components of the galaxies, with advancing post-starburst age. Emission line spectra show associated nuclear activity in two of the merged galaxies, and in one case radio lobes aligned with the displaced gas reservoir. These early results suggest that a kinetic process (possibly feedback from black hole activity) is driving the quick truncation of star formation in these systems, rather than a simple exhaustion of gas supply.
Comments: 12 pages, 9 figures, accepted for publication in MNRAS
**********************************
I don't see any necessary contradiction. Say MOST die from strangulation, that is the primary cause.
But there is a small class of galaxies that "die young". Inexplicably stop forming new stars, and turn from blue to red.
The other is here:
http://arxiv.org/abs/1505.03143
Strangulation as the primary mechanism for shutting down star formation in galaxies
Yingjie Peng, Roberto Maiolino, Rachel Cochrane
(Submitted on 12 May 2015)
Local galaxies are broadly divided into two main classes, star-forming (gas-rich) and quiescent (passive and gas-poor). The primary mechanism responsible for quenching star formation in galaxies and transforming them into quiescent and passive systems is still unclear. Sudden removal of gas through outflows or stripping is one of the mechanisms often proposed. An alternative mechanism is so-called "strangulation", in which the supply of cold gas to the galaxy is halted. Here we report that the difference between quiescent and star forming galaxies in terms of stellar metallicity (i.e. the fraction of metals heavier than helium in stellar atmospheres) can be used to discriminate efficiently between the two mechanisms. The analysis of the stellar metallicity in local galaxies, from 26,000 spectra, clearly reveals that strangulation is the primary mechanism responsible for quenching star formation, with a typical timescale of 4 billion years, at least for local galaxies with a stellar mass less than 10^11 solar masses. This result is further supported independently by the stellar age difference between quiescent and star-forming galaxies, which indicates that quiescent galaxies of less than 10^11 solar masses are on average observed four billion years after quenching due to strangulation.
Published in Nature on 14 May 2015 ( http://dx.doi.org/10.1038/nature14439 )
11 pages, 9 figures (4 in mainarticle 5 more in the extra material.)
 
Last edited by a moderator:

1. How do galaxies die?

Galaxies can die through a process called "galactic cannibalism" where larger galaxies absorb smaller ones, eventually depleting all of their gas and halting star formation. Other factors such as collisions with other galaxies, interactions with supermassive black holes, and the effects of dark matter can also contribute to a galaxy's death.

2. What are the contradictions between two papers about galaxy death?

The contradictions between two papers about galaxy death can vary, but some common disagreements include the role of dark matter in galaxy death, the importance of mergers and interactions, and the timescale of the death process. These contradictions can arise from differences in data analysis methods, theoretical assumptions, or conflicting observational evidence.

3. Can a galaxy be revived after it dies?

Technically, no. Once a galaxy has exhausted all of its gas and stopped forming new stars, it is considered "dead." However, some scientists propose that interactions with other galaxies or the effects of supermassive black holes may reignite star formation in a dead galaxy, giving it a second chance at life.

4. How long does it take for a galaxy to die?

The timescale for galaxy death can vary greatly depending on the specific circumstances of the galaxy. Some galaxies may die relatively quickly after a major collision or interaction, while others may slowly exhaust their gas over billions of years. Additionally, the definition of "death" for a galaxy is debated, making it difficult to pinpoint an exact timescale.

5. Is there a consensus among scientists about how galaxies die?

No, there is not a clear consensus among scientists about how galaxies die. While certain mechanisms and processes are generally accepted, there is ongoing debate and research about the specifics and relative importance of each factor. Additionally, the vastness and complexity of the universe make it difficult to draw definitive conclusions about galaxy death.

Similar threads

How do galaxies die? Contradictions between two papers.
    • New Member Introductions
Replies
1
Views
386

Hot Threads

Recent Insights

Back
Top