An official website of the United States government
If you could time travel to the central U.S. 300 million years ago, you would find yourself at the equator of the supercontinent Pangea. At first you might enjoy a warm climate, surrounded by seas filled with life. But, after some millions of years, the seas would vanish as the climate turned increasingly hot, dry, and hostile. Billowing dust would engulf you, and nearly all life on Earth would vanish in an event called the Great Dying. How do we know? Geoscientists reconstruct past landscapes and climates by drilling into ancient sediments—tiny grains of sand and silt. These tiny particles tell us how fast the mountains rose and which way the wind blew. Microscopic fossils reveal water and air temperatures. And miniature bubbles trapped in salt preserve actual fossil water, from nearly 300 million years ago. Travel back in time with us to explore the Great Dying.
more »
« less
A network of superconducting gravimeters as a detector of matter with feeble nongravitational coupling
Abstract Hidden matter that interacts only gravitationally would oscillate at characteristic frequencies when trapped inside of Earth. For small oscillations near the center of the Earth, these frequencies are around 300 μHz. Additionally, signatures at higher harmonics would appear because of the non-uniformity of Earth’s density. In this work, we use data from a global network of gravimeters of the International Geodynamics and Earth Tide Service (IGETS) to look for these hypothetical trapped objects. We find no evidence for such objects with masses on the order of 10 14 kg or greater with an oscillation amplitude of 0.1 r e . It may be possible to improve the sensitivity of the search by several orders of magnitude via better understanding of the terrestrial noise sources and more advanced data analysis. Graphical abstract
more »
« less
- Award ID(s):
- 1707875
- PAR ID:
- 10222562
- Date Published:
- Journal Name:
- The European Physical Journal D
- Volume:
- 74
- Issue:
- 6
- ISSN:
- 1434-6060
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)Dark matter may be composed of self-interacting ultralight quantum fields that form macroscopic objects. An example of which includes Q-balls, compact non-topological solitons predicted by a range of theories that are viable dark matter candidates. As the Earth moves through the galaxy, interactions with such objects may leave transient perturbations in terrestrial experiments. Here we propose a new dark matter signature: an asymmetry (and other non-Gaussianities) that may thereby be induced in the noise distributions of precision quantum sensors, such as atomic clocks, magnetometers, and interferometers. Further, we demonstrate that there would be a sizeable annual modulation in these signatures due to the annual variation of the Earth velocity with respect to dark matter halo. As an illustration of our formalism, we apply our method to 6 years of data from the atomic clocks on board GPS satellites and place constraints on couplings for macroscopic dark matter objects with radii R<104km, the region that is otherwise inaccessible using relatively sparse global networks.more » « less
-
ABSTRACT The discs of active galactic nuclei (AGNs) have emerged as rich environments for the production and capture of stars and the compact objects that they leave behind. These stars produce long gamma-ray bursts (GRBs) at their deaths, while frequent interactions among compact objects form binary neutron stars and neutron star–black hole binaries, leading to short GRBs upon their merger. Predicting the properties of these transients as they emerge from the dense environments of AGN discs is key to their proper identification and to better constrain the star and compact object population in AGN discs. Some of these transients would appear unusual because they take place in much higher densities than the interstellar medium. Others, which are the subject of this paper, would additionally be modified by radiation diffusion, since they are generated within optically thick regions of the accretion discs. Here, we compute the GRB afterglow light curves for diffused GRB sources for a representative variety of central black hole masses and disc locations. We find that the radiation from radio to ultraviolet and soft X-rays can be strongly suppressed by synchrotron self-absorption in the dense medium of the AGN disc. In addition, photon diffusion can significantly delay the emergence of the emission peak, turning a beamed, fast transient into a slow, isotropic, and dimmer one. These would appear as broad-band correlated AGN variability with a dominance at the higher frequencies. Their properties can constrain both the stellar populations within AGN discs and the disc structure.more » « less
-
Quantum objects, such as atoms, spins, and subatomic particles, haveunique physical properties that could be useful for many different applications, ranging from quantum information processing to magnetic resonance imaging. Molecular species also exhibit these quantum properties, and, importantly, these properties are fundamentally tunable by synthetic design, unlike ions isolated in a quadrupolar trap, for example. In this comment, we distill multiple, distinct, scientific efforts into an emergent field that is devoted to designing molecules that mimic the quantum properties of objects like trapped atoms or defects in solids. Mimicry is endemic in inorganic chemistry and featured heavily in the research interests of groups across the world. We describe this new field of using molecular inorganic chemistry to mimic the quantum properties (e.g. the lifetime of spin superpositions, or the resonant frequencies thereof) of other quantum objects as “quantum mimicry.” In this comment, we describe the philosophical design strategies and recent exciting results from the application of these strategies.more » « less
-
Abstract We present design considerations for the Transiting Exosatellites, Moons, and Planets in Orion (TEMPO) Survey with the Nancy Grace Roman Space Telescope. This proposed 30 days survey is designed to detect a population of transiting extrasolar satellites, moons, and planets in the Orion Nebula Cluster (ONC). The young (1–3 Myr), densely populated ONC harbors about a thousand bright brown dwarfs (BDs) and free-floating planetary-mass objects (FFPs). TEMPO offers sufficient photometric precision to monitor FFPs with M >1 M J for transiting satellites. The survey is also capable of detecting FFPs down to sub-Saturn masses via direct imaging, although follow-up confirmation will be challenging. TEMPO yield estimates include 14 (3–22) exomoons/satellites transiting FFPs and 54 (8–100) satellites transiting BDs. Of this population, approximately 50% of companions would be “super-Titans” (Titan to Earth mass). Yield estimates also include approximately 150 exoplanets transiting young Orion stars, of which >50% will orbit mid-to-late M dwarfs. TEMPO would provide the first census demographics of small exosatellites orbiting FFPs and BDs, while simultaneously offering insights into exoplanet evolution at the earliest stages. This detected exosatellite population is likely to be markedly different from the current census of exoplanets with similar masses (e.g., Earth-mass exosatellites that still possess H/He envelopes). Although our yield estimates are highly uncertain, as there are no known exoplanets or exomoons analogous to these satellites, the TEMPO survey would test the prevailing theories of exosatellite formation and evolution, which limit the certainty surrounding detection yields.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1140/epjd/e2020-10069-8
