Study Findings: Constraining Cosmological Parameters Using the Cluster Mass–Richness Relation

Posted on by onespaceman2000

If you don’t understand the research title, you are not alone. The abstract is even worse:

The cluster mass–richness relation (MRR) is an observationally efficient and potentially powerful cosmological tool for constraining the matter density Ωm and the amplitude of fluctuations σ8 using the cluster abundance technique. We derive the MRR relation using GalWCat19, a publicly available galaxy cluster catalog we created from the Sloan Digital Sky Survey-DR13 spectroscopic data set. In the MRR, cluster mass scales with richness as $\mathrm{log}{M}_{200}=\alpha +\beta \mathrm{log}{N}_{200}$. We find that the MRR we derive is consistent with both the IllustrisTNG and mini-Uchuu cosmological numerical simulations, with a slope of β ≈ 1. We use the MRR we derived to estimate cluster masses from the GalWCat19 catalog, which we then use to set constraints on Ωm and σ8. Utilizing the all-member MRR, we obtain constraints of Ωm = ${0.31}_{-0.03}^{+0.04}$ and σ8 = ${0.82}_{-0.04}^{+0.05}$, and utilizing the red member MRR only, we obtain Ωm = ${0.31}_{-0.03}^{+0.04}$ and σ8 = ${0.81}_{-0.04}^{+0.05}$. Our constraints on Ωm and σ8 are consistent and very competitive with the Planck 2018 results.

Where is Carl Sagan when you need him? I know these are scientific journals, but plain language abstracts should be possible.

Luckily, the university released a press release on the study findings. Here is the bottom line:

A UC Merced researcher and her teammates around the world have succeeded in measuring the total amount of matter in the universe for the second time. A new paper in the Astrophysical Journal, titled “Constraining Cosmological Parameters using the Cluster Mass-Richness Relation,” shows that matter makes up 31% of the universe, with the remainder consisting of dark energy — answering one of the most interesting and important questions in cosmology.

Now that wasn’t too hard. If you want to read the paper itself, you can find the details here.

Good luck.

Space Stories: Mars Ascent Vehicle, Dark Matter Stars, and a New Russian Space Station

Posted on by onespaceman2000
Image (Credit): Artist’s rendering of the Mars Ascent Vehicle. (NASA)

Here are some recent stories of interest.

—NASA/JPJ.com : “NASA Mars Ascent Vehicle Continues Progress Toward Mars Sample Return“

NASA’s Mars Ascent Vehicle (MAV) recently reached some major milestones in support of the Mars Sample Return program. The Mars Ascent Vehicle would be the first launch of a rocket from the surface of another planet. The team developing MAV conducted successful tests of the first and second stage solid rocket motors needed for the launch. Mars Sample Return will bring scientifically selected samples to Earth for study using the most sophisticated instrumentation around the world. This strategic partnership with ESA (European Space Agency) features the first mission to return samples from another planet. The samples currently being collected by NASA’s Perseverance Rover during its exploration of an ancient river delta have the potential to reveal the early evolution of Mars, including the potential for ancient life.

—ScienceNews : “The James Webb Telescope May Have Spotted Stars Powered by Dark Matter“

The James Webb Space Telescope has spotted objects in the early universe that might be a new kind of star — one powered by dark matter. These “dark stars” are still hypothetical. Their identification in JWST images is far from certain. But if any of the three candidates — reported in the July 25 Proceedings of the National Academy of Sciences — turn out to be this new type of star, they could offer a glimpse of star formation in the early universe, hint at the nature of dark matter and possibly explain the origins of supermassive black holes.

—CNN : “Russia Proposes Joint Research Module on Space Station for China, India, Brazil and South Africa“

The head of Russia’s space agency has extended an offer to Moscow’s partners in the BRICS group – Brazil, India, China and South Africa – to participate in the construction of a joint module for its planned orbital space station, state media reported Monday. Construction of the planned space station follows Moscow’s decision last year to end its decades-long partnership with NASA and withdraw from the aging International Space Station – one of the last remaining channels of cooperation between Russia and the United States.

Space Stories: More Moon Missions, a Two-Faced Star, and Missing Dark Matter

Posted on by onespaceman2000
Image (Credit): An artist’s rendering of NASA’s VIPER Moon rover. (NASA/Daniel Rutter)

Here are some recent stories of interest.

—Ars Technica : “NASA Starts Building Ice-hunting Moon Rover“

The search for ice at the Moon’s poles has loomed large in the field of lunar science since an instrument on an Indian satellite discovered water molecules inside shadowed crater floors more than a decade ago. NASA is now assembling a golf cart-size rover to drive into the dark polar craters to search for ice deposits that could be used by future astronauts to make their own rocket propellant and breathable air. “A large group of people have been working on this idea for 10-plus years,” said Anthony Colaprete, project scientist for NASA’s Volatiles Investigating Polar Exploration Rover (VIPER) mission.

—Caltech: “Two-Faced Star Exposed“

In a first for white dwarfs, the burnt-out cores of dead stars, astronomers have discovered that at least one member of this cosmic family is two faced. One side of the white dwarf is composed of hydrogen, while the other is made up of helium. “The surface of the white dwarf completely changes from one side to the other,” says Ilaria Caiazzo, a postdoctoral scholar at Caltech who leads a new study on the findings in the journal Nature. “When I show the observations to people, they are blown away.”

—Instituto de Astrofísica de Canarias: “The Puzzle of the Galaxy with No Dark Matter“

A team of scientists, led by the researcher at the IAC and the University of La Laguna (ULL) Sebastién Comerón, has found that the galaxy NGC 1277 does not contain dark matter. This is the first time that a massive galaxy (it has a mass several times that of the Milky Way) has not shown evidence for this invisible component of the universe. “This result does not fit in with the currently accepted cosmological models, which include dark matter,” explains Comerón.

ESA’s Euclid Space Telescope Safely Launched

Posted on by onespaceman2000
Credit: ESA

Earier today, the European Space Agency’s (ESA) Euclid Space Telescope was safely launched from Cape Canaveral on a Space X Falcon 9 rocket (though the original plan was to use a Russian Soyuz rocket until the invasion nixed that idea). The space telescope is destined for the Sun-Earth Lagrange point 2 (L2), which is an average distance of 1 million miles beyond Earth’s orbit. It will join the James Webb Space Telescope.

In addition to the 1.2 meter diameter telescope, the mission includes two scientific instruments: a visible-wavelength camera (the VISible instrument, VIS) and a near-infrared camera/spectrometer (the Near-Infrared Spectrometer and Photometer, NISP). 

The focus of the new space telescope will be to create a 3D map of the universe to better understand dark matter and dark energy. As noted on the ESA’s website, Euclid hopes to answer these questions:

  • What is the structure and history of the cosmic web?
  • What is the nature of dark matter?
  • How has the expansion of the Universe changed over time?
  • What is the nature of dark energy?
  • Is our understanding of gravity complete?

It is a tall order for this new telescope. Astronomer Isobel Hook from the UK’s Lancaster University put it this way to BBC News:

It will be like setting off on a ship before people knew where land was in different directions. We’ll be mapping out the Universe to try to understand where we fit into it and how we’ve got here – how the whole Universe got from the point of the Big Bang to the beautiful galaxies we see around us, the Solar System and to life.

Space Stories: Launch of the Euclid Space Telescope, Mercury Flyby, and a Super Hot Brown Dwarf

Posted on by onespaceman2000
Image (Credit): Artist’s rendering of the ESA’s Euclid Space Telescope. (ESA, CC BY-SA 3.0 IGO)

Here are some recent stories of interest.

—NASA/JPL: “NASA to Provide Coverage for Launch of ESA ‘Dark Universe’ Mission“

The ESA (European Space Agency) and SpaceX are targeting no earlier than 11:11 a.m. EDT (8:11 a.m. PDT) Saturday, July 1, to launch the Euclid spacecraft. Euclid is an ESA mission with contributions from NASA that will shed light on the nature of dark matter and dark energy, two of the biggest modern mysteries about the universe.

—Sky&Telescope: “BepiColombo Mission Makes Third Mercury Flyby“

An intrepid space mission had another brief glimpse of its final destination this week, as the European Space Agency’s BepiColombo flew past Mercury for a third time. The team confirms that the spacecraft is in good health post flyby, and that all instruments performed as planned. “Everything went very smoothly with the flyby and the images from the monitoring cameras taken during the close-approach phase of the flyby have been transmitted to the ground,” said Ignacio Clerigo (ESA) in a recent press release. “While the next Mercury flyby isn’t until September 2024, there are still challenges to tackle in the intervening time.”

—Phys.org: “Discovery of a Brown Dwarf Hotter than the Sun“

An international team of astronomers has discovered a planet-like object that is hotter than the sun. Their report has been accepted for publication in the journal Nature Astronomy and is currently available on the arXiv pre-print server. Brown dwarfs are sometimes called failed stars and do not qualify for the category of either a planet or a star. In this new effort, the researchers have identified one that orbits a star so closely that its temperature is hotter than our sun.