The region around the galaxy NGC 1052-DF4, taken by the IAC80 telescope at the Teide Observatory in ... [+]
Dark matter theory has long been sacrosanct in mainstream astronomical circles. Rarely do astronomers contradict the tenet that some 85 percent of all matter in the cosmos is dominated by unseen matter that only weakly interacts with gravity.
Thus, it came as a surprise that doubt was cast on its existence by recent Hubble Space Telescope observations of two massive galaxies that appeared to be altogether devoid of this exotic matter.
But in a paper submitted to The Astrophysical Journal, an international team of scientists detail observations on NGC 1052-DF4, the second galaxy purported to harbor little or no such dark matter. They argue that NGC 1052-DF4, a massive galaxy some 45 million light years away in the southern constellation of Cetus, is being almost completely stripped of this strange matter via gravitational interactions with its nearby galactic neighbor, NGC 1035.
In fact, NASA asserts that the forces driving NGC 1035 to interfere with NGC 1052-DF4 are tearing the latter apart.
Deep optical imaging of NGC 1052-DF4 has revealed that this galaxy is undergoing tidal disruption, write the authors, caused by its interaction with its neighbor, NGC 1035. Dark matter is less concentrated than stars, and therefore during interactions is preferentially stripped from satellites galaxies, they report.
How does such stripping actually work?
Like the friction of chalk on a blackboard, Mireia Montes, a postdoctoral fellow at the University of New South Wales in Australia and the paper’s lead author, told me. As you write with the chalk, the chalk’s particles are deposited in the direction of your script, she says.
New data from the NASA/ESA Hubble Space Telescope provides further evidence for tidal disruption in ... [+]
By rote, as the galaxy continues its interaction with its massive galactic neighbor, the stripped chalk particles would get deposited in the direction of the orbit of the galaxy, says Montes. In this case, what we can see that NGC 1052-DF4’s stars are actually beginning to be stripped from their host galaxy, she says.
Such research provides case studies in how and why large galaxies actually form. Dark matter helps to form galaxies as it provides sort of the gravitational well where ordinary matter can sit and cool down and form stars, says Montes.
It also acts as a protective shield. Without this dark matter shield, says Montes, the galaxy would be very unstable and prone to gravitational influence from external forces. Thus, she says, such galaxies wouldn’t survive in an environment where there are more massive galaxies would swallow up these dark matter-stripped galaxies.
We also know from simulations that the dark matter content has to decrease by some 90 percent for the interaction to start affecting the stars, she says.
These new more accurate observations also provided new distance measurements to the galaxy, NGC 1052-DF2. In 2018, a team of Yale University astronomers reported that NGC 1052–DF2 was also devoid of dark matter. But these new observations solve that mystery.
We argue instead that a closer distance to the galaxy than the one measured in 2018 solves the dark matter peculiarities of the NGC 1052-DF2 galaxy, says Montes. But a closer distance does not help in the case of NGC 1052-DF4; it’s still missing dark matter, she says.
And for physics as we know it to work, theorists still need dark matter.
Without the presence of dark matter, primordial gas would lack enough gravitational pull to start collapsing and forming new galaxies, says Montes. And once a galaxy is stripped of its dark matter, Montes says that this exotic matter ends up becoming part of galaxy responsible for the stripping. In this case, that would be the cigar-like, spiral galaxy NGC 1035.
“In time, NGC 1052-DF4 will be cannibalized by the large system around NGC 1035, with at least some of their stars floating free in deep space,” team member Ignacio Trujillo of the Instituto de Astrofísica de Canarias in Spain, said in a statement.
https://news.google.com/__i/rss/rd/articles/CBMibmh0dHBzOi8vd3d3LmZvcmJlcy5jb20vc2l0ZXMvYnJ1Y2Vkb3JtaW5leS8yMDIwLzExLzI4L25hc2FzLWh1YmJsZS1zcG90cy1nYWxheHktYmVpbmctc3RyaXBwZWQtb2YtZGFyay1tYXR0ZXIv0gFyaHR0cHM6Ly93d3cuZm9yYmVzLmNvbS9zaXRlcy9icnVjZWRvcm1pbmV5LzIwMjAvMTEvMjgvbmFzYXMtaHViYmxlLXNwb3RzLWdhbGF4eS1iZWluZy1zdHJpcHBlZC1vZi1kYXJrLW1hdHRlci9hbXAv?oc=5
2020-11-29 00:50:39Z
52781212188584
Tidak ada komentar:
Posting Komentar