Эрдэмтэд хий болон харанхуй матер агуулсан боловч од үүсгэдэггүй “харанхуй галактик”-ын шинэ нэр дэвшигчийг олж тогтоов.
Одон орон судлаачид сансрын уудамд од үүсэхэд шаардлагатай бүхий л бүрэлдэхүүн хэсгийг агуулсан атлаа од үүсгэж чаддаггүй “харанхуй галактикууд” оршин байж болзошгүйг таамаглаж байна. Эдгээр биетүүд нь харанхуй матер болон устөрөгчийн хийгээр бүрддэг боловч оддын тоо нь маш цөөн эсвэл огт байдаггүй аж. Энэхүү үзэгдлийг судлах нь галактик үүсэх үйл явцыг тайлбарлах Lambda-CDM загварыг сорих боломжийг эрдэмтдэд олгож байгаа юм.
Swinburne University of Technology-ийн судлаачид Arecibo Observatory болон Хятадын Five-Hundred-Meter Aperture Spherical Radio Telescope-ийн ажиглалтын мэдээллийг харьцуулах замаар AGC 322753 хэмээх сонирхолтой биетийг илрүүлжээ. Энэхүү объект нь Нарнаас 2 тэрбум дахин их масстай устөрөгчийн үүлнээс тогтох боловч одоогоор од илрээгүй байна. Гэсэн хэдий ч судлаачид уг биетийн хэмжээ нь бүрэн “одгүй” байх боломжгүйг тэмдэглэж, хэрэв батлагдвал энэ нь одгүй гэгдэх хамгийн аварга том галактик болох юм.
Уг нээлтийг Monthly Notices of the Royal Astronomical Society сэтгүүлд нийтэлжээ. Бусад харанхуй галактикийн нэр дэвшигчдээс ялгаатай нь AGC 322753 нь эргэлдэж байж болзошгүй шинж тэмдэгтэй байна. Радио долгионы ажиглалтаар хийн үүлний нэг хэсэг нь Дэлхий рүү ойртож, нөгөө хэсэг нь холдож байгааг харуулсан хоёр тусдаа оргил утга илэрсэн нь уг галактикийг эргэлдэж байгааг илтгэж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
Some galaxies appear to contain all the ingredients needed to make stars, yet have failed to produce almost any.
Scientists have puzzled over why for years. Recent findings suggest that these “dark galaxies”—that is, galaxies that contain gas and dark matter but few or no stars—may be lurking throughout the cosmos. Finding them could help astronomers understand why some galaxies form stars while others remain dark, and test the best models of galaxy formation.
Researchers’ most successful model of the cosmos, known as Lambda-CDM, assumes the existence of two invisible ingredients: dark energy, the mysterious property thought to be driving the accelerating expansion of the universe, as well as cold dark matter, a hypothetical substance that physicists think makes up about 85 percent of the universe’s matter.
Clumps of dark matter, called haloes, provide the gravitational scaffolding for galaxies to form and grow, according to the model. Gas collects inside these haloes, eventually cooling and collapsing to form stars. But astronomers are still trying to understand why this process appears to happen in some haloes but not others.
One possibility is that some contain vast quantities of hydrogen gas, yet form very few stars. That would make them extremely difficult to spot.
Now, researchers have found a promising candidate for such a dark galaxy and published their findings in the Monthly Notices of the Royal Astronomical Society. The object, known as AGC 322753, contains roughly 2 billion times the sun’s mass in hydrogen, yet appears to have no stars, though the researchers note that it is too big to be totally starless. However, if confirmed, it would be an unusually massive example of a starless galaxy.
Researchers at Swinburne University of Technology in Australia made the discovery by comparing observations from two existing radio surveys, one conducted by the Arecibo Observatory in Puerto Rico and the other by China’s Five-Hundred-Meter Aperture Spherical Radio Telescope. Both telescopes had picked up a massive cloud of hydrogen.
Although other researchers have identified several dark galaxy candidates over the past decade, this one stands out for another reason: It may be rotating.
Hydrogen gas emits radio waves at a signature wavelength, which shortens when the gas moves toward Earth and stretches when it moves away. The signal from AGC 322753 shows two distinct peaks, suggesting that one side of the gas cloud is moving towards us while the other is receding.
