UMD: Six Galaxies Caught Undergoing Sudden, Dramatic Transitions

[bystander]

UMD-Led Study Captures Six Galaxies Undergoing Sudden, Dramatic Transitions
University of Maryland | CMNS | 2019 Sep 18

Zwicky Transient Facility observations reveal surprising transformations from sleepy LINER galaxies to blazing quasars within months

A new study led by University of Maryland astronomers documented six sleepy, low-
ionization nuclear emission-line region galaxies (LINERs; left) suddenly transforming
into blazing quasars (right), home to the brightest of all active galactic nuclei. The
researchers suggest they have discovered an entirely new type of black hole activity
at the centers of these six LINER galaxies. Image credits: (Left; infrared & visible
light imagery): ESA/Hubble, NASA and S. Smartt (Queen's University Belfast);
(Right; artist’s concept): NASA/JPL-Caltech

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Galaxies come in a wide variety of shapes, sizes and brightnesses, ranging from humdrum ordinary galaxies to luminous active galaxies. While an ordinary galaxy is visible mainly because of the light from its stars, an active galaxy shines brightest at its center, or nucleus, where a supermassive black hole emits a steady blast of bright light as it voraciously consumes nearby gas and dust.

Sitting somewhere on the spectrum between ordinary and active galaxies is another class, known as low-ionization nuclear emission-line region (LINER) galaxies. While LINERs are relatively common, accounting for roughly one-third of all nearby galaxies, astronomers have fiercely debated the main source of light emission from LINERs. Some argue that weakly active galactic nuclei are responsible, while others maintain that star-forming regions outside the galactic nucleus produce the most light.

A team of astronomers observed six mild-mannered LINER galaxies suddenly and surprisingly transforming into ravenous quasars—home to the brightest of all active galactic nuclei. The team reported their observations, which could help demystify the nature of both LINERs and quasars while answering some burning questions about galactic evolution ... Based on their analysis, the researchers suggest they have discovered an entirely new type of black hole activity at the centers of these six LINER galaxies. ...

A New Class of Changing-look LINERs ~ Sara Frederick et al

• Astrophysical Journal 883(1):31 (2019 Sep 20) DOI: 10.3847/1538-4357/ab3a38
  arXiv.org > astro-ph > arXiv:1904.10973 > 24 Apr 2019 (v1), 16 Aug 2019 (v2)