Research Highlights

Jul 11, 2024 | Imprints of the Local Bubble and dust complexity on dust polarization

Magnetic fields that permeate the interstellar medium (ISM) play an important role in various astrophysical processes, such as star formation. Unfortunately, magnetic fields are difficult to detect directly, as they have no effect on neutral photons—the light by which we view the Universe. Magnetic fields do affect the vast clouds of dust in our Galaxy by aligning the dust grains, resulting in the light they emit also being aligned, or polarized. By measuring the polarization of the dust’s emission, we can infer the structure of the interstellar magnetic field over the sky.

May 2, 2024 | Spotting the Universe’s oldest light from the Atacama Desert

Three flights and about 26 hours from Stanford’s campus, on a cold, dry, and remote mountain high in the Atacama Desert, sits the Simons Observatory, a cosmic microwave background (CMB) experiment which will soon begin to map this ancient light with exquisite precision. Since it is the furthest light source in our Universe, however, studying the CMB is particularly difficult. Ground-based telescopes such as the Simons Observatory must be constructed in some of the most remote corners of the globe. Water vapor in our atmosphere perturbs astronomical measurements, so scientists build telescopes in the dry, thin air of high-altitude deserts. The Atacama Desert in Chile is one such location, where some areas among the Andes Mountains are nearly 50 times drier than California’s Death Valley.

Mar 21, 2024 | Using Machine Learning to find quasar lenses in DESI data

Have you ever looked through a wine glass and noticed objects farther away appear distorted? This effect, caused by the bending of light as it passes through the curved surface, is somewhat similar to strong gravitational lensing; like the wine glass warping light from distant objects, a foreground galaxy warps the appearance of a galaxy behind it by magnifying it, distorting it into arcs, and/or creating multiple images of it [Figure 2]. In my research, I use machine learning and data from the Dark Energy Spectroscopic Instrument (DESI) to look for a specific type of gravitational lens: a quasar lensing a background galaxy. But I want to learn about the lens itself, not the galaxy behind it.

Dec 4, 2023 | Not just summer students: Undergrads bring game to research all year ‘round

Summer is undergrad season at universities and research institutes. A plethora of programs exist that place enthusiastic, ambitious undergraduates with scientist-mentors who can provide them with an introduction to scientific research and keep them busy over the summer months. But ambitious undergrads are often ambitious 12 months out of the year, not three. David Wendt and Arlene Aleman are just two of the undergrads who have demonstrated how much a motivated undergraduate can contribute to a research project during the school year.

Aug 25, 2023 | Looking for dark matter with the world’s most sensitive radio

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?

Jul 6, 2023 | The connection between supermassive black holes and dark matter halos

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?

Jun 2, 2023 | Unravelling magnetic knots in sunspots

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.

May 5, 2023 | How you can combat climate change with Astronomers for Planet Earth

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).

Mar 24, 2023 | Studying the Inner Depths of Pulsar Wind Nebulae Using IXPE X-Ray Polarization Data

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…

Feb 16, 2023 | Developing Astrophysical “Apps” for LSST

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.

Jan 13, 2023 | Aliens: Could Be Out There, But Don’t Trust the Clickbait

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.

Nov 25, 2022 | IXPE helps solve black hole jet mystery

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?