Quasars - Blog Posts

Webb Telescope Captures Images of Quasar Host Galaxies in Early Universe. Read full article here

June 28, 2023 - In a groundbreaking discovery, scientists utilizing the James Webb Space Telescope (JWST) have successfully captured images of starlight from two massive galaxies hosting actively growing black holes, known as quasars. These images reveal the earliest epoch to date in which light from stars has been detected around a quasar, less than a billion years after the Big Bang. The findings shed light on the formation of black holes and their relationship with host galaxies in the early universe.

The Study and Findings:

Led by researchers from the Kavli Institute for the Physics and Mathematics of the Universe and the Peking University Kavli Institute for Astronomy and Astrophysics, the study utilized a combination of ground-based observations from the Subaru Telescope and space-based observations from the JWST. The team focused on two quasars, HSC J2236+0032 and HSC J2255+0251, which were discovered through Subaru Telescope's deep survey program. These quasars, located when the universe was around 860 million years old, provided an opportunity to study the properties of their host galaxies. Read full article here.

Ep. 23 Quasars and Blazars - HD and the Void

Hear an overview of two of the major types of active galaxies: quasars and blazars! I discuss the history of the study of quasars as well as where we're going with future studies of these extragalactic objects.

When I was in Ireland in 2013, I kept seeing signs for ‘quasar.’ I finally learned that it’s the European way of saying laser tag. It has nothing to do with quasars, which are a specific type of a specific type of galaxy. Listen to this week’s (pretty short) podcast on two types of active galaxies: quasars and blazars.

Below the cut, I have the transcript, sources, music credits, and timeline of people I talked about! If you have suggestions for topics I could cover, please send me a Tumblr message or tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Please subscribe on iTunes, rate my podcast and maybe review it, and tell friends if you think they’d like to hear it!

(My thoughts on the next episode are the SOFIA observatory, Chuck Yaeger, or the great Stephen Hawking. The next episode will go up April 2nd.)

Glossary

active galaxy or active galactic nucleus- a galaxy with a small core of emission embedded at the center. This core is typically very variable and very bright compared to the rest of the galaxy. These galaxies emit much more energy than they should; this excess energy is found in the infrared, radio, UV, and X-ray regions of the electromagnetic spectrum.

blazar - a subcategory of active galaxy, it is an extremely bright, distant object, powered by a black hole, which emits massive amounts of energy. It is distinct from a quasar because it is even brighter.

extragalactic objects - objects outside our Milky Way galaxy.

interferometry - a group of techniques to extract information from superimposing electromagnetic waves to create interference. In radio astronomy, this is done by using a wide spread of receivers to look at the same distant object, then bringing that data together with a correlator that can create a larger, clearer picture than an individual radio telescope alone could.

lunar occultations - when stars pass behind the Moon. This is the basis for a method of determining and mapping star positions.

quasar - a subcategory of active galaxy, it is an extremely bright, distant object, powered by a black hole, which emits massive amounts of energy. It is distinct from a blazar because it is less-bright. The name is a contraction of “quasi-stellar radio source” (which is not necessarily true of all quasars—90% are radio-quiet).

torus - a donut shape.

Script/Transcript

Timeline

Walter Baade, German (1893-1960)

Rudolph Minkowski, German-American (1895-1976)

Fritz Zwicky, Swiss (1898-1974)

Gordon Stanley, New Zealander (1921-2001)

John Bolton, English-Australian (1922-1993)

Owen Bruce Slee, Australian (1924-2016)

Allan Rex Sandage, American (1926-2010)

Cyril Hazard, English (1928- )

Maartin Schmidt, Dutch (1929- )

Hong-Yee Chiu, American (1932- )

Stephen Hawking, English (1942 -2018)

Jedidah Isler

Sources

Active Galaxies via NASA (Dec 2016)

Galaxy shapes via Cornell University (April 2000)

Galaxies and Black Holes by David Merritt, published on NED by Caltech and NASA

Cyril Hazard via University of Pittsburgh

The Discovery of Quasars and its Aftermath via Journal of Astronomical History and Heritage (2014)

“Characteristically, Fritz Zwicky (1898–1974; Figure 11) immediately pointed out that ‘All of the five quasi-stellar galaxies described individually by Sandage (1965) evidently belong to the subclass of compact galaxies with pure emission spectra previously discovered and described by the present writer. (Zwicky, 1965: 1293).’ A few years later, Zwicky was less circumspect and wrote: ‘In spite of all these facts being known to him in 1964, Sandage attempted one of the most astounding feats of plagiarism by announcing the existence of a major new component of the Universe: the quasi-stellar galaxies ... Sandage‘s earthshaking discovery consisted in nothing more than renaming compact galaxies, calling them ‘interlopers‘ and quasistellar galaxies, thus playing the interloper himself. (Zwicky and Zwicky, 1971: xix)’”

Lunar occultations via Sky and Telescope

Quasars and Blazars by Matthew Whiting (a chapter in his thesis, What made the quasar blush? Emission mechanisms in optically-red quasars) via the Australia Telescope National Facility (2000)

Jedidah Isler on quasars and blazars via TED Talks (March 2015)

Quasar definition via Space.com (Feb 2018)

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘Into The White’ by Pixies off their album Wave of Mutilation.

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught