Spin fluctuations show how galaxies grow out of the cosmic web

Spin fluctuations show how galaxies grow out of the cosmic web

Examples of SAMI galaxies with a central bulge and a surrounding disk. Credit: Hyper Supreme-Cam Subaru and Pan-STARSS

The alignment between the rotation of galaxies and the large-scale structure of the universe reveals the processes by which the various components of galaxies are formed.

The structure of the universe is widely traced through the distribution of galaxies. This “cosmic web” consists of giant filamentous structures that connect huge groups of galaxies.

A new study was published in Monthly Notices of the Royal Astronomical Society He found that galaxies with larger bulges tend to rotate perpendicular to the filaments in which they are embedded, while galaxies with smaller bulges tend to rotate parallel to these filaments.

“It’s all about a block swellingAstrophysicist Dr Stefania Barsanti of the Australian National University, lead author of the research paper and member of the ASTRO 3D Center of Excellence says.

Galaxies that are mostly disk-shaped, with a low-mass bulge, tend to have them The axis of rotation parallel to the nearest strings. This is because it basically consists of the gas falling on the wick and “rolling it up”. Galactic bulges grow as galaxies merge, generally as they move along a filament. Therefore, mergers also tend to “flip” the alignment between galactic rotation and filaments from parallel to orthogonal.”

says Professor Scott Crum, an astronomer at the University of Sydney and co-author of the paper.

This discovery sheds light on the composition of two major components of galaxies, and how they relate to the structures and large-scale motions of matter in the cosmic web.

“Our motive was to try to understand why galaxies rotate and how they are acquired angular momentum of the materials that make up it,” Dr. Parsanti says.

“Through this study, we can understand how mergers play an important role in the formation of galaxies, both the central bulge component and the rotational permutation,” she says. “This refers to specific formation channels of how galaxies begin to rotate and how the rotation changes as the galaxy develops.”

Although this development has been suggested before computer simulationThis study is the first time scientists have used direct observation to confirm that the growth of the galaxy’s central bulge can cause the alignment to be inverted.

“This is a subtle signal that is really hard to detect in the observations,” Dr. Parsanti says.

This became possible with the advent of integrated field spectroscopy, a technology in which an optical instrument combines spectroscopy and imaging capabilities to build a three-dimensional image of a galaxy while at the same time resolving its internal motions.

This study used a spectrometer called SAMI, attached to the 3.9-meter-wide Anglo-Australian Telescope located in Siding Spring, New South Wales.

The researchers used SAMI to survey 3,068 galaxies between 2013 and 2020. This massive amount of data took years to study and provided direct evidence for the published paper.

“By scanning the SAMI Galaxy, we have spatially resolved spectroscopy allowing us to map the galaxy, with spectra at many points across the galaxy,” says Dr. “This tells us the internal motions of stars and gases within the galaxy, so that we can measure their total rotation. These results will inform the next big stage of our research, the Hector Galaxy Survey. Hector is the next generation galactic spectrometer that has replaced SAMI at the Anglo-Australian Telescope, which we will use to survey the About 30,000 galaxies.”

Professor Stuart Wyeth of the University of Melbourne, who is director of ASTRO 3D, says the paper advances the center’s main goals of tracing the distribution of matter from the earliest eras in the universe to the present day, and building a three-dimensional picture of the formation and evolution of the universe we see today.

“Using the power of the SAMI Galactic Survey, which measures the three-dimensional structure of individual galaxies as well as their position in space, this paper demonstrates how mass movements in galaxies and galactic positions are related, and is a key part in understanding how galaxies cluster together,” says Professor Wyeth.

The study was conducted in collaboration with researchers from the Australian National University, University of Sydney, Johns Hopkins University, University of Hamburg, University of Cambridge and Macquarie University.


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more information:
Stefania Barsanti et al, SAMI Galaxy Survey: Fluctuating spindle alignment is strongly associated with bulge growth, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac2405

Submitted by the ARC Center of Excellence for All 3D Sky Astrophysics (ASTRO 3D)

the quote: Spin Fluctuations Showing How Galaxies Grow from the Cosmic Web (2022, Oct 4th) Retrieved Oct 5, 2022 from https://phys.org/news/2022-10-flips-galaxies-cosmic-web.html

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