While neutrinos were hypothesized by Wolfgang Pauli back in 1930, they remain among the most mysterious particles within the Standard Model of particle physics. We now know that there are three types of neutrinos, and neutrino oscillation experiments have shown that there are at least two types which have mass. Current experiments have not yet been able to nail down the precise masses of the three neutrinos, but have placed upper bounds on sum of their masses. These upper bounds tell us that neutrinos have to be the lightest of all Standard Model particles, more than six orders of magnitude lighter than the electron!
The SuperCDMS SNOLAB project, a multi-institutional effort led by SLAC, is expanding the hunt for dark matter to particles with properties not accessible to any other experiment.
How machine learning can help researchers relate dark-matter-only and hydrodynamic simulations, and how this mapping can shed light on the small-scale challenges associated with cold dark matter.
Near the turn of the century, two seminal papers pointed out a striking discrepancy between the number of dark matter subhalos around Milky Way-like systems in dark-matter-only (DMO) simulations and the number of observed dwarf satellite galaxies around the Milky Way (MW). Historically, this discrepancy (shown graphically in the figure below) led to the notion of the "missing satellites problem" (MSP)—not the issue of where multiple Mars-bound satellites have disappeared to, but rather the idea that we observe significantly fewer dwarf satellite galaxies (by a factor of about 10!) in the Local Group than predicted by the standard cold dark matter (CDM) cosmological model.
Is it possible to learn how the jets from small black holes a few solar masses in size behave by studying the biggest, most extreme, most relativistically distorted jets from full-fledged quasars, the monstrous billion solar mass black holes at the centers of giant galaxies? Remarkably the answer is YES!
Supermassive black holes in the centers of giant elliptical galaxies can sometimes produce powerful relativistic outflows called jets. Blazars are a special class of these galaxies with the unique property of having their jets oriented within a small angle from our line of sight. (For more on blazar jets, see the KIPAC blog post, Where have all the magnetic fields disappeared to?). Because of that preferential alignment and the fact that jets move with speeds close to the speed of light, extreme aberration of light and time dilation effects take place, distorting the observed properties of the objects.
Often in the world of astronomy and astrophysics, unexpected observations lead to new ideas and understanding. However, there are occasionally some models that are built up more traditionally from theories to observational predictions. This is a story of one such model—that of the very first stars in the universe, called, somewhat counterintuitively, Population III (Pop III) stars. We haven’t seen Pop III stars yet because of how long ago they first formed—and then died.
In Part I of this 2-part series on what astronomers do while observing, we looked at what happens when we take wide-field data for the cosmological side of things, and here in Part 2 we will continue with discussing the other mode that most people think of when they imagine what astronomers do at a telescope: searching for specific interesting objects.
I recently returned from an observing run at a telescope in Chile, and I thought our readers might wonder what astronomers do when they’re observing. After all, it can’t all be sitting around romantically staring up at the stars, right? So here’s a detailed description of what I did when I was observing for those who have wondered what actual observing is like.
Nov 27, 2017 | Simulating the universe as the ultimate Big Data problem
In the early summer of 1945, physicist Bob Christy asked fellow physicist Richard Feynman to carry out a task as quickly as possible. The deadline was the Trinity nuclear test, the first nuclear bomb and the culmination of years of secret work by Manhattan Project scientists. The task was to predict the total energy that would be released by the Gadget device, the prototype implosion bomb designed at Los Alamos.
Nov 14, 2017 | A three-dimensional step towards sorting out the GRB zoo
A powerful tool for characterizing and classifying gamma-ray bursts (GRBs) has recently been presented by an international team of researchers led by KIPAC member Dr. Maria Dainotti (Marie Curie outgoing Fellow at INAF, Italy and Stanford University and assistant professor at Jagiellonian University, Poland).
Oct 15, 2017 | An event that blew away the astronomical world
On the morn of Thursday, August 17, 2017 the LIGO-Virgo Collaboration (LVC) gravitational wave detectors saw a binary neutron star (BNS) collision in gravitational waves—and kind of blew up the astronomical world who was in on it, that day.
Why do I say this, after the announcement of the discovery of gravitational waves from a binary black hole (BBH) coalescence already made such major "ripples" amongst those who pay attention to things astronomical, just 1 1/2 years ago? (Resulting in the Nobel Prize being awarded for this, on October 3, 2017).
Sep 21, 2017 | Probing the planet formation environment
As an astronomer, I think I live in a spectacularly exciting time to be studying the process of planet formation. Little needs to be said about how dramatically the Kepler satellite telescope and other exoplanet surveys have revolutionized our understanding of the exoplanet population, as these kinds of discoveries pop up in the news on a seemingly daily basis. We now know that the planet formation process produces a diverse set of final products, many of which (such as hot Jupiters and super Earths) look very different from the planets in our own solar system.
For decades, cosmologists have been attempting to piece together the history and composition of the Universe. Since we now know that ~95% of the Universe’s mass-energy content takes the form of invisible dark matter and dark energy, this is a very difficult task indeed. However, with such enormous catalogs of galaxies such as those produced by the Dark Energy Survey (DES), we can use what we observe about the visible matter in the Universe (in the form of stars and galaxies) to infer the behavior of dark matter and dark energy.