They were under a huge pile of unmatched socks
Missing Black Hole Report: Hundreds Found!
ScienceDaily (Oct. 25, 2007) — Astronomers have unmasked hundreds of black holes hiding deep inside dusty galaxies billions of light-years away.
The massive, growing black holes, discovered by NASA's Spitzer and Chandra space telescopes, represent a large fraction of a long-sought missing population. Their discovery implies there were hundreds of millions of additional black holes growing in our young universe, more than doubling the total amount known at that distance.
"Active, supermassive black holes were everywhere in the early universe," said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. "We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself." Dickinson is a co-author of two new papers appearing in the Nov. 10 issue of the Astrophysical Journal. Emanuele Daddi of the Commissariat a l'Energie Atomique in France led the research.
The findings are also the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths building monstrous black holes at their cores.
For decades, a large population of active black holes has been considered missing. These highly energetic structures belong to a class of black holes called quasars. A quasar consists of a doughnut-shaped cloud of gas and dust that surrounds and feeds a budding supermassive black hole. As the gas and dust are devoured by the black hole, they heat up and shoot out X-rays. Those X-rays can be detected as a general glow in space, but often the quasars themselves can't be seen directly because dust and gas blocks them from our view.
"We knew from other studies from about 30 years ago that there must be more quasars in the universe, but we didn't know where to find them until now," said Daddi.
Daddi and his team initially set out to study 1,000 dusty, massive galaxies that are busy making stars and were thought to lack quasars. The galaxies are about the same mass as our own spiral Milky Way galaxy, but irregular in shape. At 9 to 11 billion light-years away, they existed at a time when the universe was in its adolescence, between 2.5 and 4.5 billion years old.
When the astronomers peered more closely at the galaxies with Spitzer's infrared eyes, they noticed that about 200 of the galaxies gave off an unusual amount of infrared light. X-ray data from Chandra, and a technique called "stacking," revealed the galaxies were, in fact, hiding plump quasars inside. The scientists now think that the quasars heat the dust in their surrounding doughnut clouds, releasing the excess infrared light.
"We found most of the population of hidden quasars in the early universe," said Daddi. Previously, only the rarest and most energetic of these hidden black holes had been seen at this early epoch.
The newfound quasars are helping answer fundamental questions about how massive galaxies evolve. For instance, astronomers have learned that most massive galaxies steadily build up their stars and black holes simultaneously until they get too big and their black holes suppress star formation.
The observations also suggest that collisions between galaxies might not play as large a role in galaxy evolution as previously believed. "Theorists thought that mergers between galaxies were required to initiate this quasar activity, but we now see that quasars can be active in unharassed galaxies," said co-author David Alexander of Durham University, United Kingdom.
"It's as if we were blindfolded studying the elephant before, and we weren't sure what kind of animal we had," added co-author David Elbaz of the Commissariat a l'Energie Atomique. "Now, we can see the elephant for the first time."
The new observations were made as part of the Great Observatories Origins Deep Survey, the most sensitive survey to date of the distant universe at multiple wavelengths.
Consistent results were recently obtained by Fabrizio Fiore of the Osservatorio Astronomico di Roma, Italy, and his team. Their results will appear in the Jan. 1, 2008, issue of Astrophysical Journal.
Maybe they should have put their picture on a milk carton.
Headline of the day
Police arrest man found in bathroom with blow-up doll (the Obscure Store)
"Well, you told us to get a room."
Breaking news: being fat doesn’t make you happy
Ideal weight varies, but obese unhappy
PHILADELPHIA, Oct. 25 (UPI) -- Different cultures have different standards for the body, but overweight children of all ethnicities are unsatisfied with how they look, a U.S. study says.
Some cultures celebrate a fuller body shape more than others, but researchers at the Center for Obesity Research and Education at Temple University in Philadelphia found that an overweight or obese child can still be unhappy with his or her body, despite acceptance from within his or her ethnic group.
Asian children had the highest levels of dissatisfaction with being overweight among all ethnic groups tested, study leader Gary Foster said.
"Culturally speaking, the ideal body shape is a lean one among Asian children," Foster said in a statement. "In African-American and Latino cultures, being lean is not always the ideal."
The researchers looked at data collected from 1,200 fourth-, fifth- and sixth-graders in 10 Philadelphia schools to determine the level of children's satisfaction with their body image.
The findings were presented in New Orleans at The North American Association for the Study of Obesity's annual scientific meeting.
This lab, are there golden arches outside?
Supersize elements created in lab
By Cristina Jimenez
US researchers have created exotic new versions of atomic nuclei including one previously thought to not exist.
The three new isotopes of magnesium and aluminium suggest other heavy variants of everyday elements could be created.
The new nuclei existed for only a fraction of a second and were created by smashing atoms at half the speed of light in a particle accelerator.
The work, published in the journal Nature, may give astrophysicists insights into the workings of stars.
"There is a second way to create super heavy nuclei: explosions in stars," said Paul Henri Heenen, a nuclear physicist at the Universite Libre de Bruxelles.
The lab experiments mimic these violent events and therefore can give astrophysicists clues about stellar processes.
The experiments will also allow theoretical physicists to test the validity of their nuclear models.
"The limit of stability of matter may be further out than previously expected," wrote Professor Dave Morrissey, one of the authors of the paper.
"It shows how much mystery remains about atomic nuclei."
Chasing heavier atoms
Physicists have known since the beginning of the 20th Century that the atomic nucleus is formed from two basic particles - protons and neutrons - that are held together by a strong nuclear force.
It is also an established fact that every atom of the same chemical element has a unique number of protons, but can have different number of neutrons - when that happens the two atoms are called isotopes.
But from the 1930s, scientists studying nuclear forces have been trying to establish the limit of how many neutrons a given number of protons can bind, a basic property of matter known as the neutron-drip line.
"The knowledge of these drip lines is crucial to our understanding of the force that binds a nucleus," said Professor Heenen
But even today, scientists are not sure exactly which combinations of protons and neutrons can make up most atomic nuclei.
One way of addressing this question is to find out how many neutrons can be artificially loaded on to nuclei of so-called quotidian elements, which contain the same number of protons but different numbers of neutrons.
Accelerating particles
This is done using a circular particle accelerator known as a cyclotron that bombards heavy atoms with other materials at very high speeds. This triggers nuclear reactions that break the initial atoms into pieces and create new heavy nuclei.
Using this technique, the Michigan State University team created and detected a super heavy isotope of magnesium, magnesium-40, containing 12 protons and 28 neutrons.
Magnesium usually contains 12 neutrons.
They also found heavier counterparts of aluminium - aluminium-42, with 13 protons and 29 neutrons and aluminium-43, with 13 protons and 30 neutrons. Aluminium normally contains 14 neutrons.
Current theories suggested aluminium-42 was unlikely to exist.
"At this point, we can't define the end of magnesium and aluminium isotopes," said Dr Morrissey.
"We need to upgrade the measurement and detection techniques for the next experiments which will allow us to detect even more heavier isotopes," he added.
"You want the really large drink? Well, our really large is called "the cosmic."
It’s all fun and games until somebody’s eye gets poked out..and giant spiders crawl out of the sewer.
Synthetic life 'no terror threat'
By Cristina Jimenez
Science reporter
Craig Venter
Dr Venter could be on the cusp of creating life
Synthetic biology can help in the fight against emerging infections, rather than aid the design of bioweapons, controversial scientist Craig Venter has told reporters.
The US scientist, who led the private sector race to map the human genome, used a briefing in central London to allay fears that his work may fall into the wrong hands.
Critics of Dr Venter's research, which aims to design the world's first synthetic life, have expressed concern.
They say that artificial microbes may have dangerous consequences, such as either escaping into the environment or being used to manufacture bioweapons.
"If Venter succeeds in creating a working bacteria then he also lifts the lid on creating bacterial bioweapons, such as anthrax, in the near future," said Jim Thomas of the ETC Group, a Canadian campaign group that has concerns over the development of genetic technology.
When there is a big shift of knowledge, we go through a cycle of fear, in which people are afraid of the unknown
Dr Craig Venter
"An equally real concern in the longer term is bio-error, the synthetic creation of organisms that escape out of our control," he added.
Dr Venter insisted that such worries about synthetic organisms were unfounded.
He maintained that antibiotic-resistant infections, such as MRSA, were much more of a threat.
According to the maverick scientist, synthetic biology could provide the most effective way of stopping infections in developing countries, such as malaria, and emerging drug-resistant superbugs.
"In the US, MRSA kills more people than Aids," he said.
Campaigners say that there are currently no international laws or oversight mechanisms to assess the safety of synthetic organisms.
They suggest that an international process is needed to put in place controls before anything is commercialised.
Dr Venter defended himself against any claims that he was exploiting the human genome for financial gain.
"If you look at the record, my institution has no human gene patents, yet my biggest critics do," he said. "The Human Gene Project has human gene patents."
In an effort to explain why his work had attracted so much critical attention, he pointed out that a similar controversy occurred at the beginning of the molecular biology era.
He said: "When there is a big shift of knowledge, we go through a cycle of fear, in which people are afraid of the unknown."
The best lack all conviction, while the worst are filled with passionate intensity.
“The best lack all conviction, while the worst are filled with passionate intensity.” We would add ..”and certainty.”
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment