Two powerful probes of dark matter on small scales—strong gravitational lensing and ultra-faint dwarf galaxies—join together to set world-leading constraints on the nature of the dark matter particle in a recent study led by KIPAC researchers, including the authors. In the process, we have shown that combining these probes provides a framework to detect “dark halos,” clumps of dark matter that have no associated visible light, using the vast amounts of deeper data promised by upcoming surveys.
Cosmology in the 2020s is in a particularly privileged position as far as scientific fields go. Soon several experiments will come online that will give us a tremendous amount of information about the so-called "dark" components of the Universe: dark matter and dark energy. But if we’re not careful, we run the risk of drawing inadequate conclusions from these rich datasets. Not because our data aren’t adequate—they’re amazing—but because our models aren’t good enough. That’s why much current work is focused on creating better predictions of the signals these experiments are designed to measure.
Neutron stars are made of highly compressed material called degenerate matter, which is so dense it must be described using the laws of quantum mechanics. As a result, NSs should have a unique relationship between mass and radius, determined by an “equation of state” (EoS). An EoS is a thermodynamic description of the entwined properties of, for example, temperature, pressure, and volume. The steam in a pressure cooker can be described by an EoS; so can the interior of a star. For neutron star-like conditions only density matters, which results in a density-dependent EoS, P(rho). But because their material is in an exotic state not found anywhere on Earth, the EoS for neutron stars remains unknown.
A new correlation has been discovered in optical observations of gamma ray bursts (GRBs) that may be the key to using GRBs as cosmological distance indicators, adding another rung to the so-called "distance ladder" that helps astronomers determine the size of the observable Universe.
While there have been extensive previous studies of mergers between two galaxies, a recent study that helps reveal what happens when three galaxies merge is one of the first to systematically look at the consequences for the supermassive black holes at their hearts when a trio of galaxies comes together.
Susan Clark, who will officially begin her appointment as KIPAC's newest faculty member on September 1, 2021, is quite familiar with the challenges inherent an observational field like astrophysics. While the main thrust of her research is reaching a broad understanding of astrophysical magnetism—including planetary and stellar fields, the immensely powerful fields of pulsars and active galactic nuclei, and the huge fields throughout galaxy clusters—one of her favorite areas of research is mapping the vast lines of magnetic force that thread through our own galaxy.
Oct 1, 2020 | Delving Back Deeper: Towards GRBs as Standard Candles
Standard candles are objects with fixed luminosities that can be calculated by taking advantage of well-established relationships between an object’s luminosity and its physical properties—relationships that are independent of the object’s distance. Such objects enable the calculation of accurate astronomical distances. The furthest well-established standard candles to date are Type Ia supernovae, but GRBs have been observed at much greater distances (up to 13.2 billion light years vs. 11 billion light years for Type Ia supernovae). Thus, GRBs could provide accurate distances to events that happened only a few hundred millions years after the Big Bang, very close to when stars began to form in the Universe.
The cosmic microwave background (CMB), the afterglow of the Big Bang, has been a treasure trove of information about the cosmos since its discovery in the 1960s. The CMB is detectable as a faint background of microwaves, which we measure with specialized telescopes in remote locations like the high Andes and the South Pole. In this research highlight, I will describe a new method by which the CMB may help solve the mystery of dark matter.
The astrophysics community recently celebrated the first direct image of a supermassive black hole by the Event Horizon Telescope. We know that the black hole they studied, the one at the center of the galaxy Messier 87 (or M87) in the Virgo Galaxy Cluster, is around six billion times as massive as our own sun, but how did it accumulate so much mass and, more generally, how and when did these massive black holes form?
Jan 30, 2020 | Taking on the blending challenge
One of the biggest challenges facing researchers who will use data from the Legacy Survey of Space and Time (LSST) provided by the Vera C. Rubin Observatory (VRO—formerly the Large Synoptic Survey Telescope) is that, as it scans the sky from its perch on a mountain top in the Chilean Andes, it will see a crowded Universe. A significant number of objects in LSST images will appear to overlap to some extent—galaxies with galaxies, stars with stars, galaxies with stars—creating uncertainties in shapes and redshifts.
Dec 6, 2019 | ICYMI: A day in the life of a cosmic-ray 'bookkeeper'
Early-career physicist Jonathan LeyVa helps build one of the world’s most sensitive dark matter detectors. LeyVa works in a clean room at the Department of Energy's SLAC National Accelerator Laboratory, where crews are building detectors for the latest in a series of Super Cryogenic Dark Matter Search (SuperCDMS) experiments. As an early-career physicist, part of his job is keeping track of how much exposure to cosmic rays—high-energy particles falling in from space—the detector components are getting. Researchers want to keep that exposure to a minimum because it could harm their ability to detect dark matter later on.
The Dark Energy Spectroscopic Instrument (DESI) is a new instrument mounted on a telescope in Arizona. On Oct. 22, it aimed its robotic array of 5,000 fiber-optic “eyes” at the night sky to capture the first images showing its unique view of galaxy light. It was the first test of a long-awaited instrument designed to explore the mystery of dark energy, which makes up about 68 percent of the universe and is speeding up its expansion.