“Exactly. When they coalesce, their combined gravitational waves carry linear momentum, sometimes enough to eject the core from a galaxy. Theoretical limits are accelerations of thousands of kilometers a second.”
“Okay, that’s possible.” Roger nodded. “Unlikely, but possible.”
“Some people think the universe hasn’t existed long enough for the massive black holes at the center of galaxies to form. That it would take longer than fifteen billion years for the million-plus solar mass monsters to exist just by stars falling into them.”
Ben entered the LIGO data into his calculation spreadsheet.
“Primordial black holes might have formed during the creation of our universe,” he continued. “Maybe the start of our universe was a giant game of billiards, with trillions of medium-sized black holes merging into the galactic cores, while some of them, like Nomad, shot free. If I’m right, I think Nomad is shrapnel left over from the Big Bang.”
He frowned at his spreadsheet. That couldn’t be right. A knot formed in his stomach, his cheeks flushing. He stared at the number on his screen. That can’t be right.
“Can you check this for me?” Ben clicked forward on the LIGO data email, sending it to Roger. “See if you can come up with a relative velocity?” He glanced at the TV. The images of street protests changed to a room with a table of men in ill-fitting suits. Scientists.
“…latest reports indicate that there is no significant radiation detected in central Rome,” said one of the men around the table, “leading our experts to conclude that the bomb over Rome was not a nuclear device.”
“What was it then?” asked the news anchor.
A grainy image of a large air transport filled the screen. An object dropped from the back of it, a parachute opening above it. A second later, the screen went white. “This is a security camera footage of what we believe to be the device detonated over the Vatican. It resembles a Russian MOAB, a ten-ton conventional munition similar to the BLU-82 used by American forces in the Vietnam War. It has a yield of about twenty tons of TNT, with a blast radius of…”
So it wasn’t a nuclear device. There was a chance. The TV switched to an aerial view of central Rome. While the Vatican, and buildings around it, were rubble, on the other side of the Tiber, the buildings stood intact. That’s where Jess and Celeste were. They had to be alive.
“Jesus Christ.”
Ben blinked and turned to Roger. “What number did you get?”
“This can’t be right,” Roger whispered.
Ben saw the shock on Roger’s face. “What did you get?”
“Eight.”
“At what combined mass?”
“About forty.”
Ben swallowed hard. “Me too.”
“What trajectory did you get?” Roger looked nervously at Ben.
“…the Pentagon is saying that Chechen rebels worked with a splinter group of the Pakistani army to steal a MOAB from the Russian army,” said the news anchor in the background. “…would never have been so bold to launch an attack, but were spurred by the announcement of Nomad which they view as a biblical event like the one described by Noah…”
Calculating the three dimensional path of an invisible object was no easy thing. Ben checked his spreadsheets, clicking in the data from LIGO. Together with the new radial velocity searches and visual observations of Uranus, it narrowed down the list of solutions. He checked the numbers again. “Declination of one-eighty-one, inclination of one-point-five with closest solar approach of seventy four million kilometers, and forty solar masses, plus or minus.”
“About what I got, too.” Roger rubbed his shaking hands together. “I guess that explains it.”
It all made sense.
They couldn’t see anything because Nomad was a black hole, and not only that, but a binary pair of them. No visible microlensing, at least not the sort they were looking for. Two smaller black holes, rotating around each other at high speed, would create a flickering microlensing that might be impossible to detect, even at close range. It wasn’t what the Gaia team was even looking for.
And the reason why it seemed to come from nowhere: eight thousand kilometers a second. Like Roger said, nothing was supposed to move that fast. Especially not something that massive.
But there was no arguing with the data.
Only in the last decade or two, humans had devices sensitive enough to perform radial velocity searches of distant stars. And in that time, scientists had measured Nomad’s presence, but the data was subtracted as some unknown dark matter mass in the nearby spiral arm of the Milky Way. And they might have been right—this might actually be a chunk of the fabled dark matter.