Since the 1960s there has been plenty of evidence to support the existence of dark matter through astrophysical and cosmological observations, and at this point we’re very confident that it exists. The question remains, though: what is dark matter actually made of? Weakly interacting massive particles (WIMPs)? Neutrinos? Primordial black holes? Or none of the above?

At the center of each galaxy lurks a supermassive black hole (SMBH). These black holes grow during phases of extreme accretion when nearby gas and dust fall into their deep gravitational wells, which we observe as active galactic nuclei (AGN). Zooming out to much greater distances, halos of dark matter surround each galaxy, extending millions of light-years. But while various galaxy properties are known to correlate with SMBHs and their dark matter halos separately, the black hole - dark matter halo connection has been less explored. How does the dark matter environment of a galaxy impact the growth and coevolution of its central supermassive black hole?

As our closest star, the Sun gives us much of the information we know about stars in general, since it’s the only one closest enough to study in detail. One intriguing feature of the Sun is sunspots, dark spots on the surface that increase and decrease in number with the Sun’s solar cycle. Sunspots seem to hold clues to solar flares and coronal mass ejections (CMEs), two energetic types of solar activity that can disrupt local “space weather”—the term given to conditions in the outermost layers of the Earth’s atmosphere such as the magnetosphere and the ionosphere, which help protect us from solar radiation and charged particles. Such disruptions can damage everything from satellites in Earth orbit to transmission lines on the surface, and even expose astronauts to dangerous radiation.

Thirty-three years ago, Voyager 1 looked back at Earth from the edge of our solar system, about 3.7 billion miles (6 billion kilometers) from the Sun. It saw, and photographed, a speck of blue floating alone in a sunbeam. The resulting picture of “the Pale Blue Dot” (as Carl Sagan termed it) shows the planet we all live on as a fraction of a pixel in a vast ocean of space. This unprecedented image and the resulting emotional impact of seeing our home planet as a vulnerable world captures the core mission of Astronomers for Planet Earth (A4E).

Neutron stars are rapidly rotating dense balls of nuclear material formed from the gravitational collapse of the cores of giant stars. Generally, we cannot see them because they are very small and don’t emit much thermal (heat) radiation. But one special class of neutron stars, called pulsars, have jets of radiation that pass by Earth once per rotation, creating a lighthouse effect whereby they appear to us as pulsating stars (hence the name "pulsar"). Many models have been proposed to explain the nature of pulsar emissions. The most basic one is called the “rotation-powered” model, where particles accelerated along the pulsar's magnetic field lines are dragged and rotated around by the spin, powering the observed synchrotron radiation and exerting a torque on the pulsar that causes it to slow down over time (known as magnetic braking). While this model allows us to approximate some pulsar parameters, such as the strength of the surface magnetic field, details of the emission process are unaccounted for. Other plausible models have been proposed, which we'll be able to better constrain using data from the Imaging X-Ray Polarimetry Explorer (IXPE), a small-mission NASA satellite…

The distance from Palo Alto to San Francisco might seem obvious when you’re looking for directions on Google Maps, but for the deep-field images of the Universe captured by enormous telescopes like the James Webb Space Telescope (JWST) and the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), two points of light can appear close together when they’re actually separated by billions of lightyears. KIPAC scientist, Eli Rykoff, toes the line between astrophysics and software engineering to develop algorithms that can accurately determine the distance between Earth and a far-away galaxy.

People have wondered whether or not there are other beings and minds beyond the Earth at least since the ancient Greek philosopher Epicurus in the third century BC. It was an active topic of theological debate through the Renaissance, and eventually imagining aliens, their worlds, and their possible visits to us became a major part of popular culture in the 20th century. Cultural takes on alien life and UFOs have ranged from the more thoughtful and philosophical to the absurdity of gray beings conspiring with international government officials. Recent declassified images and videos of seemingly strange shapes darting across the sky may have caused a media storm, but the real story that needs to be told is that we finally know something about the likelihood of intelligent life in the Universe.

Some of the brightest objects in the sky are called blazars. They consist of a supermassive black hole feeding off material swirling around it in a disk, which can create two powerful jets perpendicular to the disk on each side. A blazar is especially bright because one of its powerful jets of high-speed particles points straight at Earth. For decades, scientists have wondered: How do particles in these jets get accelerated to such high energies?

Biopolymers (large molecules operating in living systems, such as DNA or proteins) possess a unique architecture: the arrangement of their atoms in space has the property of specific chirality (or handedness; the word “chiral” comes from Greek for “hands”). How this happened is unknown and solving it is central to understanding the origin of life because the property of homochirality—where all biomolecules of a certain type have the same chirality—allows the biopolymers to adopt stable helical structures. As a result, their helices spiral in only one direction, and this direction is the same for all living organisms.

Dark matter’s stubborn resistance to discovery has forced us to reevaluate what it may look like. If it is much lighter than we’ve assumed, there must be more of it around to make up the total mass required to hold galaxies together. Our challenge: the signals these lighter particles would leave in terrestrial detectors are smaller than any we’ve ever set out to measure. To answer that challenge, DM physicists are constructing the coldest, quietest, most sensitive particle detectors ever made.

For more than a decade, scientists and engineers from the SLAC National Accelerator Laboratory (SLAC) have been leading the development of the world’s largest digital camera for the Legacy Survey of Space and Time (LSST) Simonyi Survey Telescope. They’ve broken Guinness World Records for highest resolution digital camera and largest lens, but the heart of the camera—a table-sized focal plane made up of nearly two hundred charge-coupled devices (CCDs)—has been a scientific study in its own right, filling thousands of research papers and countless PhD dissertations. 

Our Universe is believed to be filled with a chaotic sea of low-frequency gravitational waves, perturbations in space-time caused by orbiting pairs of supermassive black holes at the centers of merging galaxies. These waves can be light-years long and astronomers have been chasing them for decades using large radio telescopes around the globe. Now a powerful new tool—one with a long association to KIPAC—has been developed, and the hunt has moved to space using gamma rays, the highest-energy form of light.