In today’s post, I will talk about a subset of compact objects (neutron stars or stellar mass black holes), which run with very high spatial velocity through the interstellar medium. Those runners, in general, imprint characteristic signatures on their way: trails and bubbles. For the case of static objects (i.e., no proper motion), which the relativistic jets (or winds) from the compact objects interact with the ambient medium, the theoretical model of the evolution has been studied well over the decades: (1) the early momentum-driven phase, where the ram pressure of the jet is significant for the dynamical evolution, (2) the energy-driven phase, where the slowed-down outflow inflates supersonically expanding…
Read More >>A sensitive new radio catalogue for M83
Something slightly different today. Recently I posted about some work I was involved with where we discovered a candidate X-ray binary in the galaxy M83. However, that work came out of a much larger project completely unrelated to X-ray binaries. For the past few years, I have been working with a number of collaborators all over the world (Rick White, Knox Long, Bill Blair, Roberto Soria, and Frank Winkler) to observe, map, and create a deep new radio catalogue of the face-on spiral galaxy M83. This work has just been accepted for publication in MNRAS, so expect to see it in full very soon. Using radio observations with the Australia…
Read More >>When black hole jets disappear
Today I will be previewing a neat result me and Tom have been working on for the past few months. It’s going to be a bit more technical than my usual post, so please bear with me. In September 2017, a new black hole X-ray binary called Maxi J1535-571 was discovered, and Tom started observing it with ATCA, an Australian radio telescope. At the same time, many of our collaborators also looked at the source with infrared, optical and X-ray observatories, producing lots of really interesting data to analyze. This is really useful because while X-ray and optical data gives us some information about the material falling towards the black…
Read More >>The Lord of the Wings: Winged and X-shaped radio galaxies
Radio galaxies are powered by a central supermassive black hole feeding on surrounding matter. Some of this matter is ejected in opposing directions along the axis of rotation of the black hole in the form of powerful relativistic jets. These jets are launched with velocities close to the speed of light and travel vast distances away from their host galaxies. They emit radiation predominantly at radio frequencies, but also emit across the entire electromagnetic spectrum. Jets have a major impact on their surroundings. They can significantly heat their environments, reduce star formation and limit the growth of galaxies. When observed at radio frequencies jets display a wide range of different appearances.…
Read More >>A young black hole blowing a huge bubble into space
Numerous black holes are hidden in the space. These compact objects are difficult to probe as light cannot escape from the strong gravities from them. Fortunately, some black holes are actively shaping their environment and in such a way, we could “catch” them. SS 443 is one of the most popular and active black hole systems that strongly influence its neighborhood. It is a young binary system that contains a 16 solar mass black hole accreting materials from a massive star orbiting around it (see Figure 1). The black hole was formed in a recent stellar explosion, which we call “supernova”. The recent time here means 20 thousand years ago,…
Read More >>A Glimpse into Supermassive Black Holes from “Observing” JAB Simulations
By Dr. Richard Anantua This past decade has been a landmark in the history of black hole astrophysics— bringing precise experimental confirmation to bear upon revolutionary predictions of Einstein’s general theory of relativity from just over a century ago. LIGO’s 2015 observation of the “chirp” signal characteristic of the merger of two black holes marked a 5.1 sigma detection of gravitational waves predicted by Einstein in 1916, and the first measurement of an astronomical signal outside the electromagnetic spectrum. In 2018, the European Southern Observatory’s GRAVITY (4 very large infrared telescopes) detected gravitational redshift from the passage of the star S2 at a near-relativistic speed of 0.03c near the pericenter…
Read More >>IceCube South Pole Neutrino Observatory
On 18 December 2010, a huge human task was accomplished. 5,160 spherical optical sensors called Digital Optical Modules (DOMs) were transported and placed under the frozen surface of Antarctica. 52 institutions from 12 countries around the globe contributed (and still do) to this collaboration. The DOMs, attached to 86 vertical “strings”, cover a cubic-kilometer area from 1,450 meters to 2,450 meters depth (see Fig. 1) and are designed to indirectly detect neutrinos. Thus the first, and so far the only, cubic-kilometer neutrino telescope was born! This telescope is called the IceCube South Pole Neutrino Observatory. Neutrinos are electrically neutral subatomic particles that interact very rarely with matter. When they do…
Read More >>The beauty of Einstein’s equations: black holes and beyond
There’s no doubt about it: Einstein’s general theory of relativity has changed the way we understand the cosmos, with its crowning glory being the discovery of black holes. Last year (2019), in May, I gave a short talk about the Event Horizon Telescope results on a webinar (link here) hosted by SPACE- India, an organization dedicated to bringing the wonders of space to school children in India. You can see the pdf of the talk here. I had a fun time interacting with them and (hopefully!) answered some of the questions from these curious young minds. I, of course, thank SPACE-India for the opportunity to reach so many kids. It…
Read More >>Fate of Jets in X-ray binaries: jet-wind interaction
Relativistic jets are ubiquitous and we can observe them in a wide range of scales: from stellar-mass objects (e.g., stellar-mass black holes, neutron stars or pulsars) to massive objects (e.g., active galactic nuclei, radio galaxies). In fact, those jets are key players in shaping our universe into what it is now. For example, jets from active galactic nuclei are powerful and capable of reaching very far from the central region of their host galaxy, it is generally accepted that they have provided a huge amount of heating into the universe. Without the heating, most galaxies might have significantly cooled down a long time ago; and had only old stars or…
Read More >>When A Black Hole Devours A Star
Black hole X-ray binaries are systems in which a stellar-mass black hole ‘feeds’ on (accretes) gas from a companion star. Gas from the star swirls around the black hole, forming an accretion disk. The accretion disk shines brightly at X-ray frequencies and black hole X-ray binaries are some of the brightest X-ray emitting sources observed in our galaxy. Black hole X-ray binaries (BHXRBs) have been observed to cycle between different ‘accretion states’. These accretion states are associated with different emission and outflow properties— Some accretion states are associated with very bright X-ray emission, while others display weak X-ray emission. In some accretion states weak outflows are driven from the disk…
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