Scientists who made headlines in March with their research on the early universe are now acknowledging that they may have been mistaken.

In a paper published Thursday, the researchers stood by their initial conclusion — that they had found long-sought evidence for a rapid ballooning of the universe a split-second after its birth.

But they said they could not rule out the possibility that a crucial signal they believe came from deep in the cosmos was actually caused by dust in the Milky Way galaxy. If true, their claim for detecting the evidence of so-called cosmic inflation right after the Big Bang would evaporate.

The March announcement was big news because it appeared to provide evidence for the inflation theory, which is widely believed by scientists. The theory says the universe expanded extremely quickly when it was far less than one-trillionth of a second old.

Using data from a telescope at the South Pole, the research team said it had found a specific pattern in light waves within the faint microwave glow left over from the Big Bang. That pattern had long been considered evidence of inflation. John Kovac of Harvard, leader of the collaboration, called it "the smoking-gun signature of inflation."

But since the announcement, some other scientists have published analyses that suggested the signal may have actually come from Milky Way dust.

Kovac and colleagues said they'd taken the potential effects of Milky Way dust into account, but the other scientists suggested they may have underestimated its effects.

Experts expect that data from upcoming research will help settle the question.

Kovac and colleagues published their paper in the journal Physical Review Letters.