銀河系X線の放射の起源として離散的な源があります
M Revnivtsev1, S Sazonov, E Churazov
1Excellence Cluster Universe, Technische Universität München, 85748, Garching, Germany. mikej@mpa-garching.mpg.de
Nature
|May 2, 2009
まとめ
銀河のX線放射は,以前は拡散した熱いガスと考えられていましたが,主に離散的な源に分解されています. これらの源は,おそらく白矮星と活発な恒星を集積し,長年の天体物理学的なパズルを解決している.
科学分野:
- 天体物理学 天体物理学
- X線天文学 X線天文学
- 銀河系天文学 銀河系天文学
背景:
- 銀河のX線放射として知られる未解のX線光は,25年間観測されてきました.
- この放射は,熱い (約10^8 K) 光学的に薄い熱プラズマと一致するスペクトルを示し,6.7 keVで突出した鉄線を特徴としています.
- 銀河円盤の浅い重力潜在力は,そのような熱い恒星間媒体を閉じ込めることができず,エネルギー補給の大きな課題 (10^43 erg s^-1) を引き起こします.
研究 の 目的:
- 銀河盤の解明されていないX線光の性質を調査するために.
- 観測されたX線放射が拡散プラズマまたは離散源から発生するかどうかを判断する.
- 銀河のX線放射に責任を負う天体の種類を特定する.
主な方法:
- およそ6〜7 keVのエネルギーでのX線データの分析.
- X線表面の明るさの分布を近赤外線データと比較して,恒星の分布を追跡する.
- 高解像度のX線観測により,点源への拡散放射を解明する.
主要な成果:
- 6~7 keVのX線放射の80%以上は,分散しているように見えますが,分離された光源に分解されます.
- これらの離散源の分布は,銀河の恒星分布と相関しています.
- 特定された源は,白矮星と冠状活性星が収束している可能性が高い.
結論:
- 銀河のX線放射は,主に拡散した熱いガスではなく,むしろ,多数の薄弱で離散的な源からの集積放射です.
- 収縮する白矮星と活発な恒星がこの放射に寄与している可能性が高い.
- この発見は,銀河の円盤にある熱い恒星間媒体のエネルギー補給という長年の問題を解決している.
関連する概念動画
01:24X-ray Imaging
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with X-rays, and by 1900, X-ray was widely...
02:39Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
01:10Generating Electromagnetic Radiations
The German physicist Heinrich Hertz (1857–1894) was the first to generate and detect certain types of electromagnetic waves in the laboratory. Starting in 1887, he performed a series of experiments that confirmed the existence of electromagnetic waves and verified that they travel at the speed of light. Hertz used an alternating-current RLC (resistor-inductor-capacitor) circuit that resonated at a known frequency and connected it to a loop of wire. High voltages induced across the gap in the...
01:10Detection of Black Holes
Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
02:18X-ray Crystallography
The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of the diffraction of X-rays by the crystal, termed X-ray crystallography.
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
01:20Atomic Emission Spectroscopy: Overview
Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from excited atoms. In AES, atoms in a sample are excited to higher energy levels by thermal energy from high-temperature sources, such as plasma, arcs, or sparks. When these excited atoms return to lower energy states, they emit light at specific wavelengths characteristic of each element. The resulting atomic emission spectrum, which consists of...