ABOUT THIS IMAGE:

This detailed view shows the central parts of the nearby active galaxy NGC 1433. The dim blue background image, showing the central dust lanes of this galaxy, comes from the NASA/ESA Hubble Space Telescope. The colored structures near the center are from recent ALMA observations that have revealed a spiral shape, as well as an unexpected outflow, for the first time.

Two international teams of astronomers have used the power of the Atacama Large Millimeter/submillimeter Array (ALMA) to focus on jets from the huge black holes at the centers of galaxies and observe how they affect their surroundings. They have respectively obtained the best view yet of the molecular gas around a nearby, quiet black hole and caught an unexpected glimpse of the base of a powerful jet close to a distant black hole.

There are supermassive black holes - with masses up to several billion solar masses - at the hearts of almost all galaxies in the Universe, including our own galaxy, the Milky Way. In the remote past, these bizarre objects were very active, swallowing enormous quantities of matter from their surroundings, shining with dazzling brilliance, and expelling tiny fractions of this matter through extremely powerful jets. In the current Universe, most supermassive black holes are much less active than they were in their youth, but the interplay between jets and their surroundings is still shaping galaxy evolution.

Two new studies, both published today in the journal Astronomy & Astrophysics, used ALMA to probe black hole jets at very different scales: a nearby and relatively quiet black hole in the galaxy NGC 1433 and a very distant and active object called PKS 1830-211.

"ALMA has revealed a surprising spiral structure in the molecular gas close to the center of NGC 1433," says Françoise Combes (Observatoire de Paris, France), who is the lead author of the first paper. "This explains how the material is flowing in to fuel the black hole. With the sharp new observations from ALMA, we have discovered a jet of material flowing away from the black hole, extending for only 150 light-years. This is the smallest such molecular outflow ever observed in an external galaxy."

The discovery of this outflow, which is being dragged along by the jet from the central black hole, shows how such jets can stop star formation and regulate the growth of the central bulges of galaxies [1].

The two new observations are just the start of ALMA's investigations into the workings of jets from supermassive black holes, near and far. Combes's team is already studying other nearby active galaxies with ALMA and the unique object PKS 1830-211 is expected to be the focus of much future research with ALMA and other telescopes.

"There is still a lot to be learned about how black holes can create these huge energetic jets of matter and radiation," concludes Ivan Martí-Vidal. "But the new results, obtained even before ALMA was completed, show that it is a uniquely powerful tool for probing these jets - and the discoveries are just beginning!"

Notes:

[1] This process, called feedback, may explain the mysterious relationship between the mass of a black hole at the center of a galaxy and the mass of the surrounding bulge. The black hole accretes gas and grows more active, but then produces jets that clear out gas from the surrounding regions and stop star formation.

Colors & Filters:

   Band              Wavelength                Telescope
Infrared (red)          814 nm         Hubble Space Telescope WFC3
Optical (green)       555 nm         Hubble Space Telescope WFC3
Millimeter (red)                          Atacama Large Millimeter/submillimeter Array
Millimeter (yellow)                     Atacama Large Millimeter/submillimeter Array
Optical (blue)         438 nm        Hubble Space Telescope WFC3