Webb and PHANGS collaboration reveal incredible networks of gas and dust in nearby spiral galaxies

posted Thursday, February 16, 2023 at 2:30 PM EDT

Researchers with the Physics at High Angular resolution in Nearby Galaxies (PHANGS) collaboration are performing the largest survey of nearby galaxies using the James Webb Space Telescope. The research includes more than 100 international researchers and is led by Janice Lee, Gemini Observatory chief scientist at the US National Science Foundation's NOIRLab and an affiliate astronomer at the University of Arizona.

The PHANGS collaboration is studying a sample of 19 spiral galaxies. So far, within Webb's first few months of scientific operations, five targets have been observed, including M74, NGC 7496, IC 5332, NGC 1365, and NGC 1433. Per the European Space Agency (ESA), the results are "astounding astronomers."

NGC 1433. The ESA writes, "NGC 1433 is classified as a Seyfert galaxy, a galaxy relatively close to Earth that has a bright, active core. The brightness and lack of dust in the MIRI image of NGC 1433 could hint at a recent merger or even collision with another galaxy. In the image of NGC 1433, blue, green, and red were assigned to Webb’s MIRI data at 7.7, 10 and 11.3, and 21 microns (the F770W, F1000W and F1130W, and F2100W filters, respectively)."

Credits: NASA, ESA, CSA, and J. Lee (NOIRLab), A. Pagan (STScI)

Images captured using Webb's Mid-Infrared Instrument (MIRI) show the "presence of a network of highly structured features within these galaxies," including brilliant glowing dust cavities and large gas bubbles lining the galactical spiral arms. ESA writes, "In some regions of the nearby galaxies observed, this web of features appears built from both individual and overlapping shells and bubbles where young stars are releasing energy."

NGC 1365 is a "double-barred spiral galaxy that lies about 56 million light-years away from Earth. It’s one of the largest galaxies currently known to astronomers, spanning twice the length of the Milky Way." ESA adds, "As revealed by the MIRI observations of NGC 1365, clumps of dust and gas in the interstellar medium have absorbed the light from forming stars and emitted it back out in the infrared, lighting up an intricate network of cavernous bubbles and filamentary shells influenced by young stars releasing energy into the galaxy's spiral arms."

Credits: NASA, ESA, CSA, and J. Lee (NOIRLab), A. Pagan (STScI)

Webb's high-resolution imaging capabilities allow astronomers to perform more in-depth research than ever. Webb's infrared imaging can "pierce through the dust" to better observe the target galaxies. MIRI can observe at specific wavelengths (7.7 and 11.3 microns) that allow observation of emissions from polycyclic aromatic hydrocarbons, which are an important ingredient for star and planet formation. "These molecules were detected by Webb in the first observations by the PHANGS program," ESA continues.

NGC 7496. ESA describes Webb's importance, "Until Webb’s high resolution at infrared wavelengths came along, stars at the earliest point of their lifecycle in nearby galaxies like NGC 7496 remained obscured by gas and dust. Webb’s specific wavelength coverage (7.7 and 11.3 microns), allows for the detection of polycyclic aromatic hydrocarbons, which play a critical role in the formation of stars and planets. In Webb’s MIRI image, these are mostly found within the main dust lanes in the spiral arms. In their analysis of the new data from Webb, scientists were able to identify nearly 60 new, undiscovered embedded cluster candidates in NGC 7496. These newly identified clusters could be among the youngest stars in the entire galaxy. At the centre of NGC 7496, a barred spiral galaxy, is an active galactic nucleus (AGN). An AGN is a supermassive black hole that is emitting jets and winds. The AGN glows brightly at the centre of this Webb image. Additionally, Webb’s extreme sensitivity also picks up various background galaxies, far distant from NGC 7496, which appear green or red in some instances."

Credits: NASA, ESA, CSA, and J. Lee (NOIRLab), A. Pagan (STScI)

With high-resolution imaging, it's possible to study galactical interactions in greater detail, allowing for a more sophisticated understanding of how galaxies evolve. The PHANGS collaboration will create datasets that align with prior observations, allowing others in the astronomical community to take advantage of Webb's work, even if they aren't part of PHANGS. So far, the PHANGS team has published 21 research papers with its initial findings, all featured in a special focus issue of The Astrophysical Journal Letters.

2/ The research team is studying a diverse sample of 19 spiral galaxies, and in Webb’s first few months of science operations the results are already astounding astronomers. pic.twitter.com/8T3xp25XGB
— ESA Webb Telescope (@ESA_Webb) February 16, 2023