How is a galaxy fed?

Image of the comic web gas simulated by Claudio Dalla Vecchia, IAC researcher. The center of the red halo shows a galaxy in the process of formation. The simulation has been carried out using the supercomputer MareNostrum, within the project EAGLE/ADGE. C
Image of the comic web gas simulated by Claudio Dalla Vecchia, IAC researcher. The center of the red halo shows a galaxy in the process of formation. The simulation has been carried out using the supercomputer MareNostrum, within the project EAGLE/ADGE. C
Advertised on

Galaxies grow forming stars from gas, but their gas reservoir is very limited. They need a continuous gas supply to keep activity during the lifetime of the Universe. However, do we know where the gas comes from? How is a galaxy fed?

“We knew it from theoretical arguments”, says Jorge Sánchez Almeida, the IAC researcher leading the work. “It falls in from the cosmic web. However, one thing is theory and something different is observation. Our work puts forward a firm observational evidence.”

The gas produced during the Big Bang is distributed in space forming something resembling a network of filaments (the so-called cosmic web; see the Figure). In the nodes of the network, where several filaments meet, galaxies grow. The pristine gas, that has been part of the cosmic web since the beginning of the Universe, falls onto the galaxy disks, providing the fresh material that keeps galaxies alive.

“In some galaxies – explains the IAC researcher Casiana Muñoz Tuñón – we observe distinct star-forming regions made out of pristine gas. Having almost exclusively hydrogen and helium, this type of pure gas is very unusual in galaxies.” Stars produce most of the chemical elements, like oxygen or carbon, and they quickly pollute the gas of a galaxy when exploding as supernovas.  “The un-polluted gas that we detect must necessarily come from the cosmic web. There is no other reasonable explanation.”   

The difficulty of the work lies in carrying out chemical analyses of extremely faint galaxies. One needs 10-m class telescopes, like the Gran Telescopio CANARIAS (GTC) used in this study. GTC is operated at the Roque de los Muchachos Observatory, in La Palma, Spain.

The work has been published in the specialized journal Astrophysical Journal Letters (see the publication here), and it has been highlighted by the American Astronomical Society. There is also a summary of the results published in the science magazine New Scientist.

Contact:

Jorge Sánchez Almeida: jos [at] iac.es (jos[at]iac[dot]es)  (+34 922 605 233). http://www.iac.es/galeria/jos/

News type
Press release

It may interest you

  • Planetary nebula M57
    Press release
    The mystery of the fullerenes in space explained
    A pioneering study from the Instituto de Astrofísica de Canarias (IAC) which combines laboratory chemistry with astrophysics, has shown for the first time that grains of dust formed by carbon and hydrogen in a highly disordered state, known as HAC, can take part in the formation of fullerenes, carbon molecules which are of key importance for the development of life in the universe, and with potential applications in nanotechnology. The results are published as a Letter to the Editor in the prestigious journal Astronomy & Astrophysics. Fullerenes are carbon molecules which are very big
    Advertised on
  • El telescopio de la red SONG en el Observatorio del Teide / Uli Fehr
    Press release
    The SONG global network celebrates its first decade of scientific research with a conference in Tenerife
    This week, the Instituto de Astrofísica de Canarias is hosting the Second SONG Scientific Congress to conclude the first decade of high-level work of this international network devoted to the study of the interior of stars and the planetary systems that surround them. The meeting, which is taking place at the headquarters of IACTEC in La Laguna from 18 to 20 September, brings together more than 50 scientists from Europe, the United States, Australia and China to discuss the latest state-of-the-art techniques in time-resolved spectroscopy and stellar astrophysics. The Stellar Observations
    Advertised on
  • Image of the Nube galaxy through different telescopes. Credit: SDSS/GTC/IAC
    Press release
    Nube, the almost invisible galaxy which challenges the dark matter model
    A group of astrophysicists led by Mireia Montes, a researcher at the Instituto de Astrofísica de Canarias (IAC), has discovered the largest and most diffuse galaxy recorded until now. The study has been published in the journal Astronomy & Astrophysics, and has used data taken with the Gran Telescopio Canarias (GTC) and the Green Bank Radiotelescope (GBT). Nube is an almost invisible dwarf galaxy discovered by an international research team led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the University of La Laguna (ULL) and other institutions. The name was
    Advertised on