An abundance of scientific and anecdotal evidence suggests that anxiety is increasing, globally and rapidly, among people of all age groups, and especially among young people. Amidst a host of contributing factors comes this highly publicized comment from well-known astrophysicist Neil deGrasse Tyson: “The universe is a deadly place. At every opportunity it’s trying to kill us.”1 While some discoveries may seem to suggest that the universe is even more dangerous than previously thought, astronomers also see—as I have often reported on—an accumulation of evidence that Earth resides in a rare, likely unique, cosmic “safe zone,” provided by our Creator.
As you may know from textbooks or my previous writings, the universe is filled with objects pouring out deadly radiation. A few examples include cataclysmic variable stars, novae, supernovae, pulsars, supernova remnants, black holes, and gamma-ray bursts. You’ve heard that various asteroids may be on a collision course with planet Earth. Now, a team of 52 astronomers from ten nations led by Matt Nicholl of Queens University, Belfast, has discovered yet another risk to advanced life—“extremely luminous, fast-cooling transients,” or, for the purposes of this article, ELFCTs.2 (Astronomers have yet to come up with an official name for these newly discovered deadly objects/events.)
While using the Asteroid Terrestrial-impact Last Alert Survey (ATLAS), Nicholl’s team detected three of these “transient” phenomena. ATLAS, unlike most supernova survey telescopes, is specially designed to detect rapidly evolving astronomical phenomena on time scales of days, as compared to weeks or months. The three events they observed occurred in massive elliptical galaxies where star formation ceased long ago, “passive” galaxies. In terms of spatial orientation, these events occurred between 13,000 and 32,000 light-years out from the center of their galaxies.
For the three events, the peak optical-wavelength luminosity rose to 16 times brighter than the peak luminosity of a Type Ia supernova (the optically brightest stellar objects previously observed), and yet their radio and x-ray emission levels were undetectable. Their brightness rose from undetectable to peak luminosity in a mere 9 days, and then faded by a factor of 6 within 15 days.
Not Supernovae At first glance, these events appeared to be a new category of supernovae. However, the team of 52 astronomers quickly ruled out this possibility. First, they noted that no conceivable supernova model would explain the rapid rise and fall in optical luminosity astronomers observed for these events. Second, no conceivable supernova model would explain the lack of detectable radio and x-ray radiation from these events.
Additionally, Type Ia supernovae exhibit consistent, uniform peak luminosities; consistent, uniform rise and fade times; and consistent, uniform spectral distributions in their radiation outputs. The observed features for all three events fail, by far, to match any of these features.
As noted, the host galaxies for the three events are all passive. They ceased star formation several hundred million or even billions of years prior to the lookback time—the time it took the light from the galaxies in which the three events occurred to reach astronomers’ telescopes. Stars massive enough to become supernovae undergo star formation, nuclear burning, and a supernova eruption all in less than a few million years.
Black Hole Encounter The team went on to consider and analyze six other possible explanations for the ELFCTs they had observed. Their work demonstrated that the only viable explanation would be a close gravitational encounter (or merger) between a relatively low-mass star with either a stellar-mass black hole (having a mass equal to a few times as large as our star, the Sun) or an intermediate-mass black hole (several hundred to several thousand times the Sun’s mass).
Intermediate-mass black holes have been found to reside, typically, at the core of globular clusters (see figure 1).3 Gravity-wave telescopes have detected the existence of stellar-mass black holes as well.4 The team concluded that the three ELFCTs they observed could best be explained as encounters between low-mass stars and stellar-mass black holes.
Figure 1: M2, a Globular Cluster 37,000 Light-Years Away M2 contains over 150,000 stars. Credit: NASA/ESA/Hubble Space Telescope/STScI
Further, the team provided a tentative estimate of the frequency with which ELFCT events are likely to occur within the universe. That figure: one such event per cubic gigaparsec per year. (A gigaparsec = 3.26 million light-years.) This occurrence rate is about 100,000 times lower than the supernova core collapse rate. The team closed their paper with a reminder that all conclusions drawn from their discovery must be acknowledged as tentative. They emphasized the need for future observations and survey programs to elucidate both the nature and occurrence of ELFCTs. Nevertheless, even their initial observations make clear that extremely luminous, fast-cooling transient events will occur almost exclusively in star clusters and galaxies where both the density and number of stars is high, more specifically, in large, dense globular clusters and in large, dense elliptical/spherical galaxies (see figure 2).
Figure 2: ESO 325-G004, an Elliptical Galaxy 450 Million Light-Years Away ESO 325-G004 contains several thousand globular clusters. Credit: NASA/ESA/Hubble Heritage Team/STScI/AURA
Design Significance Based on the team’s assessment of their remarkable discovery, Earth resides in a location well protected from the dangers of ELFCTs. The Milky Way Galaxy (MWG) has the lowest known ratio of stellar mass to total mass of any known large spiral galaxy. Its stellar mass to total mass ratio is only half that of the Andromeda Galaxy’s. Our galaxy also has a low number of globular clusters as compared with other large galaxies, a total of just 152 compared to several thousand.
Our solar system resides 26,000 light-years distant from the galactic center, where stellar density is highest. In other words, our solar system exists in what’s considered an “under-dense” region of the MWG. So, in the context of ELFCT risk, Earth appears to reside in the safest location within the safest galaxy in which advanced life can conceivably exist.
In fact, the MWG belongs to a galaxy group where no giant galaxies or large spheroidal/ellipsoidal galaxies exist. The galaxy groups in the vicinity of the MWG’s group are all relatively small and devoid of giant galaxies. The nearest galaxy clusters are the Virgo, Centaurus, Hydra, Pavo, and Fornax clusters. Of these clusters, only the Virgo and Centaurus contain more than a few giant ellipsoidal/spheroidal galaxies. Given that the giant ellipsoidal/spheroidal galaxies in the Virgo and Centaurus clusters are more than 50 million light-years away, they present little, if any, ELFCT risk to advanced life on Earth.
The discovery of ELFCTs represents one more factor limiting the possible existence of advanced life in other regions of the universe beyond Earth. Provision of a safe space amid the countless dangers identified by astrophysicists, including Neil deGrasse Tyson, suggests to me the careful planning of a purposeful, personal Creator, more specifically, the God of the Bible.
M. Nicholl et al., “AT 2022aedm and a New Class of Luminous, Fast-Cooling Transients in Elliptical Galaxies,” Astrophysical Journal Letters 954, no. 1 (September 1, 2023): L28, doi:10.3847/2041-8213/acf0ba.
Manuel Arca Sedda et al., “The DRAGON-II Simulations – II. Formation Mechanisms, Mass, and Spin of Intermediate-Mass Black Holes in Star Clusters with Up to 1 Million Stars,” Monthly Notices of the Royal Astronomical Society 526, no. 1 (November 2023): 429–442, doi:10.1093/mnras/stad2292.
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration, “GETC-3: Compact Binary Coalescences Observed by LIGO and Virgo during the Second Part of the Third Observing Run,” to be published in Physical Review X (October 23, 2023), arXiv:2111.03606.
