Jim Baen’s Universe
Page 7
The crisp heat faded as he rose up the grade to the dry plateau, where the Array sprawls on railroad lines in its long valley. Along the Y-shaped rail line the big dishes could crawl, ears cupped toward the sky, as they reconfigured to best capture in their “equivalent eye” distant radiating agonies. The trip through four-lane blacktop edged with sagebrush took most of a day. When Ralph arrived Harkin had been observing a radio galaxy for eight hours.
“Plenty more useful than my last six hours,” he said, and Harkin grinned.
Harkin wore jeans, a red wool shirt and boots and this was not an affectation. Locals described most of the astronomers as “all hat and no cattle,” a laconic indictment of fake westerners. Harkin’s face seemed to have been crumpled up and then partly smoothed out-the effect of twenty years out here.
The radio galaxy had an odd, contorted look. A cloud of radio emitting electrons wrapped around Harkin’s target-a brilliant jet. Harkin was something of a bug about jets, maintaining that they had to be shaped by the magnetic fields they carried along. Fields and jets alike all were offhand products of the twirling disk far down in the galactic center. The black holes that caused all this energy release were hard to discover, tiny and cloaked in gas. But the jets carried out to the universe striking advertisements, so they were the smoking gun. Tiny graveyards where mass died had managed to scrawl their signatures across the sky.
Ralph looked at the long, spindly jet in Harkin’s radio images. It was like a black-and-white of an arrow. There was a lot of work here. Hot-bright images from deep down in the churning glory of the galactic core, then the long slow flaring as the jet moved above the galactic disk and met the intergalactic winds.
Still, it adamantly kept its direction, tightly arrowing out into the enveloping dark. It stretched out for many times the size of its host galaxy, announcing its presence with blaring radio emission. That came from the spiraling of high-energy electrons around magnetic field lines, Ralph knew, yet he always felt a thrill at the raw radio maps, the swirls and helical vortices bigger than swarms of stars, self-portraits etched by electrons alive with their mad energies.
At the very end, where it met the intergalactic gas, the jet got brighter, saturating the images. “It’s turned toward us, I figure,” Harkin said. “Bouncing off some obstruction, maybe a molecular cloud.”
“Big cloud,” Ralph said.
“Yeah. Dunno what it could be.”
Mysteries. Many of them would never be solved. In the murder of stars, only tattered clues survived.
Harkin was lean and sharp-nosed, of sturdy New England stock. Ralph thought Harkin looked a lot like the jets he studied. His bald head narrowed to a crest, shining as it caught the overhead fluorescents. Harkin was always moving from the control boards of the ganged dishes to the computer screens where images sharpened. Jets moved with their restless energies, but all astronomers got were snapshots. Black holes spewed out their advertisements for around a hundred million years, so Harkin’s jet was as old as the dinosaurs. To be an astronomer was to realize one’s mayfly nature.
“Hope I haven’t gotten you to come all this way for nothing.” Harkin brought up on a screen the total file on G369.23-0.82.
He recognized one image from the first observations a year before, when Feretti from Bologna had picked it up in the background of some jet observations. Over the last three years came others, Andy’s and Ralph’s extensive maps, polarization data files, the works. All digital; nobody kept much on paper anymore.
“Y’see here?” An observing schedule sheet. “The times when G369.23-0.82 is in the sky, I’ve only got three slices when we’re reconfiguring the dishes. Each maybe half an hour long.”
“Damn!” He grimaced. “Not much.”
“No.” Harkin looked a bit sheepish. “When I made that promise to you, well, I thought better of it the next day. But you’d already left for your flight in Geneva.”
“ Vin Local,” Ralph said. “It hit me pretty hard, too.”
Harkin nodded at his feet, embarrassed. “Uh, okay, so about G369.23-0.82-“
“I call it the Bullet. Easier than G369.23-0.82.”
“Oh yeah.” Hankin shrugged. “You said that in Briancon.”
But what could he do in half hour fragments? He was thinking this through when Harkin asked the same question.
“Andy pretty well showed there was no pulsar beam,” Harkin said helpfully, “so…?”
Ralph thumbed through his notes. “Can I get good clarity at the front end? The Bullet’s bow shock?”
Harkin shook his head, looking disappointed. “No way, with so little observing time. Look, you said you had some out of the box ideas.”
Ralph thought furiously. “How about the Bullet’s tail, then?”
Harkin looked doubtful, scribbled a few numbers on a yellow lined pad. “Nope. It’s not that luminous. The wake dies off pretty fast behind. Confusion limited. You’d get nothing but noise.”
Ralph pointed. “There’s a star we can see at the edge of the Bullet.”
Harkin nodded. “A foreground star. Might be useful in narrowing down how far away it is.”
“The usual methods say it’s a long way off, maybe halfway across the galaxy.”
“Um. Okay, leave that for later.”
Ralph searched his mind. “Andy looked for pulses in what range?” He flipped through his notes from Briancon. “Short ones, yes-and nothing slower than a ten second period.”
Harkin nodded. “This is a young neutron star. It’ll be spinning fast.”
Ralph hated looking like an amateur in Harkin’s eyes, but he held his gaze firmly. “Maybe. Unless plowing through all that gas slows it faster.”
Harkin raised his eyebrows skeptically. “The Mouse didn’t slow down. It’s spinning at about a tenth of a second period. Yusef-Zadeh and those guys say it’s maybe 25,000 years old.”
Twenty- five thousand years was quite young for a pulsar. The Mouse pulsar was a sphere of nothing but neutrons, a solar mass packed into a ball as small as San Francisco, spinning around ten times a second. In the radio-telescope maps that lighthouse beam came, from a dot at the very tip of a snout, with a bulging body right behind, and a long, thin tail: mousy. The Mouse discovery had set the paradigm. But just being first didn’t mean it was typical.
Ralph set his jaw, flying on instinct-“Let’s see.”
So in the half hours when the dish team, instructed by Harkin, was slewing the big white antennas around, chugging them along the railroad tracks to new positions, and getting them set for another hours-long observation-in those wedges, Ralph worked furiously. With Harkin overseeing the complex hand-offs, he could command two or three dishes. For best use of this squeezed schedule, he figured to operate in the medium mic�
�rowave band, around 1 or 2 Ghz. They had been getting some interference the last few days, Harkin said, maybe from cell phone traffic, even out here in the middle of a high desert plateau-but that interference was down around 1 Ghz, safely far below in frequency. He need not worry about callers ringing each other up every few minutes and screwing up his data.
He took data carefully, in a way biased for looking at very long time fluctuations. In pulsar theory, a neutron star was in advanced old age by the time the period of its rotation, and so the sweeping of its lighthouse beam, was a second long. They harnessed their rotation to spew out their blaring radiation-live fast, die young. Teenage agonies. Only they didn’t leave beautiful corpses-they were corpses. Pulsars should fade away for even slower rates; only a handful were known out in the two or three minute zone.
So this search was pretty hopeless. But it was all he could think of, given the half hour limit.
He was dragging by the time he got his third half hour. The dish team was crisp, efficient, but the long observing runs between his slices got tedious. So he used their ample computing resources to process his own data-big files of numbers that the VLA software devoured as he watched the screens. Harkin’s software had fractured the Bullet signal into bins, looking for structure in time. It caressed every incoming microwave, looking for repeating patterns. The computers ran for hours.
Hash, most of it. But then…
“What’s that?” He pointed to a blip that stuck up in the noisy field. The screen before him and Harkin was patchy, a blizzard of harmonics that met and clashed and faded. But as the Bullet data ran and filtered, a peak persisted.
Harkin frowned. “Some pattern repeating in the microwaves.” He worked the data, peering at shifting patterns on the screen. “Period of…lessee…forty-seven seconds. Pretty long for a young pulsar.”
“That’s got to be wrong. Much too long.”
In astronomy it paid to be a skeptic about your work. Everybody would be ready to pounce on an error. Joe Weber made some false detections of gravitational waves, using methods he invented. His reputation never fully recovered, despite being a brilliant, original scientist.
Harkin’s face stiffened. "I don't care. That's what it is."
"Got to be wrong.”
“Damn it, Ralph, I know my own codes.”
“Let’s look hard at this."
Another few hours showed that it wasn’t wrong.
“Okay- funny, but it’s real.” Ralph thought, rubbing his eyes. “So let’s look at the pulse itself.”
Only there wasn’t one. The pattern didn’t spread over a broad frequency band. Instead, it was there in the 11 gigaHertz range, sharp and clear-and no other peaks at all.
“That’s not a pulsar,” Harkin said.
Ralph felt his pulse quicken. “A repeating brightness. From something peaking out of the noise and coming around to our point of view every forty-seven seconds.”
“Damn funny.” Harkin looked worried. “Hope it’s not a defect in the codes.”
Ralph hadn’t thought of that. “But these are the best filter codes in the world.”
Harkin grinned, brown face rumpling like leather. “More compliments like that and you’ll turn my pretty little head.”
****
So Harkin spent two hours in deep scrutiny of the VLA data processing software-and came up empty. Ralph didn’t mind because it gave him to think. He took a break partway through-Harkin was not the sort to take breaks at all-and watched a Cubs game with some of the engineers in the Operations room. They had a dish down for repairs but it was good enough to tip toward the horizon and pick up the local broadcast from Chicago. The Cubs weren’t on any national ‘cast and two of the guys came from UC, where the C was for Chicago. The Cubs lost but they did it well, so when he went back Ralph felt relaxed. He had also had an idea. Or maybe half of one.
“What if it’s lots bigger than a neutron star?” he asked Harkin, who hadn’t moved from his swivel chair in front of the six-screen display.
“Then what’s the energy source?”
“I dunno. Point is, maybe it’s something more ordinary, but still moving fast.”
“Like what?”
“Say, a white dwarf-but a really old, dead one.”
“So we can’t see it in the visible?” The Hubble telescope had already checked at the Bullet location and seen nothing.
“Ejected from some stellar system, moving fast, but not a neutron star-maybe?”
Harkin looked skeptical. “Um. Have to think about it. But…what makes the relativistic electrons, to give us the microwaves?”
That one was harder to figure. Elderly white dwarfs couldn’t make the electrons, certainly. Ralph paused and said, “Look, I don’t know. And I have to get back to UCI for classes. Can I get some more time wedged in between your reconfigs?”
Harkin looked skeptical. “I’ll have to see.”
“Can you just send the results to me, when you can find some time?”
“You can process it yourself?”
“Give me the software and, yeah, sure.”
Harkin shrugged. “That forty-seven second thing is damn funny. So…okay, I suppose…”
“Great!” Ralph was tired but he at least had his hand in the game. Wherever it led.
****
Ralph spent hours the next day learning the filter codes, tip-toeing through the labyrinth of Harkin’s methods. Many thought Harkin was the best big-dish observer in the world, playing the electronics like a violin.
Harkin was a good teacher because he did not know how to teach. Instead he just showed. With it came stories and examples, some of them even jokes, and some puzzling until Harkin changed a viewing parameter or slid a new note into the song and it all came clear. This way Harkin showed him how to run the programs, to see their results skeptically. From the angular man he had learned to play a radio telescope as wide as a football field like a musical instrument, to know its quirks and deceptions, and to draw from it a truth it did not know. This was science, scrupulous and firm, but doing it was an art. In the end you had to justify every move, every conclusion, but the whole argument slid forward on intuition, like an ice cube skating on its own melt.
****
“Say, Andy,” Ralph said casually into his cell phone, looking out the big windows at New Mexico scrub and the white radio dishes cupped toward the sky. “I’m trying to remember if you guys looked at long periods in your Bullet data. Remember? We talked about it at Briancon.”
“Bullet? Oh, G369.23-0.82.”
“Right, look, how far out did you go on period?”
A long pause. Ralph thought he could hear street noise. “Hey, catch you at a bad time?”
“No, just walking down Mass Ave., trying to remember. I think we went out to around thirty second periods. D
idn’t see a damn thing.”
“Oh, great. I’ve been looking at the Bullet again and my preliminary data shows something that, well, I thought I’d check with you.”
“Wow.” Another pause. “Uh, how slow?”
Ralph said cautiously, “Very. Uh, we’re still analyzing the data.”
“A really old pulsar, then. I didn’t think they could still radiate when they were old.”
“I didn’t, either. They’re not supposed to.” Ralph reminded himself to check with the theorists.
“Then no wonder we couldn’t find its supernova remnant. That’s faded, or far away.”
“Funny, isn’t it, that we can pick up such weak signals from a pulsar that’s halfway across the galaxy. Though it has been getting brighter, I noticed.”
Andy sounded puzzled. “Yeah, funny. Brighter, um. I wonder if it shows up in any earlier survey.”
“Yeah, well I thought I’d let you know.”
Andy said slowly, "You know, I may have glimpsed something, but will get back to you."
They exchanged a few personal phrases and Ralph signed off.
Harkin was working the screens but turned with eyebrows raised.
Ralph said, “Bingo.”
****
As soon as Irene came into the coffee shop and they kissed in greeting, he could see the curiosity in her eyes. She was stunning in her clingy blue dress, while he strutted in his natty suit. He had told her to dress up and she blinked rapidly, expectant. “Where are we going tonight?”