Julian Shapiro, now an undergraduate astrophysics student at the University of California, Berkeley, discovered three new galaxies while he was still in high school. The galaxies, named Shapiro Dwarf Galaxies I, II, and III, are a new type of galaxy altogether, known as 'backsplash galaxies'.
'It was very exciting,' Julian tells Metro, 'though my excitement was drawn out over a long time as it took months to estimate their distances.'
What are backsplash galaxies?
Backsplash galaxies are cosmic drifters that have had all their star-forming gases sucked up by larger galaxies. They have long been predicted but never definitively observed in the wild. The Shapiro Dwarf Galaxies are about 25 million light-years away from Earth.
'The backsplash candidates I discovered are dwarf galaxies, which are flung around much more easily, and each contains only a few hundred thousand stars compared to a few hundred billion in our galaxy,' Julian says.
Discovery and findings
Between classes, Julian used archival telescope data to predict likely locations in the nearby universe. The best contenders are dwarf galaxies, clusters of just a few hundred thousand stars. The three galaxies he spotted are gasless loners but are far away from their alleged cosmic gas thief, M101, a pinwheel-shaped galaxy made of one trillion stars.
Julian says M101 robbed the Shapiro Dwarf Galaxies of their star-making gas and chucked them aside, making them among the first resolved 'backsplash galaxy' candidates. His findings were published in the Astrophysical Journal this month.
Implications for cosmology
'Their potential ejection history can help explain unexpected populations of dwarf galaxies that are isolated and not forming new stars,' Julian adds. If M101 is hurling around backsplash galaxies, it suggests that the Milky Way could be doing the same.
The findings, which will require follow-up studies, have long been predicted by the standard model of cosmology, called Lambda-CDM. According to the model, after the Big Bang, gravity crammed cosmic gas into stars and black holes, then dragged them together into galaxies.
