astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

, a Lyman-alpha blob (LAB) is a huge concentration of a gas emitting the Lyman-alpha emission line. LABs are some of the largest known individual objects in the

Universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...

. Some of these gaseous structures are more than 400,000

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s across. So far they have only been found in the high-

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

universe because of the

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

nature of the Lyman-alpha emission line. Since

Earth's atmosphere The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weathe ...

is very effective at filtering out UV

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...

s, the Lyman-alpha photons must be redshifted in order to be transmitted through the atmosphere. The most famous Lyman-alpha blobs were discovered in 2000 by Steidel et al. Matsuda et al., using the Subaru Telescope of the

National Astronomical Observatory of Japan The (NAOJ) is an astronomy, astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii and Chile. It was established in 1988 as an amalgamation of three existing research organizations - the To ...

extended the search for LABs and found over 30 new LABs in the original field of Steidel et al., although they were all smaller than the originals. These LABs form a structure which is more than 200 million light-years in extent. It is currently unknown whether LABs trace overdensities of galaxies in the high-redshift universe (as high redshift radio galaxies—which also have extended Lyman-alpha halos—do, for example), nor which mechanism produces the Lyman-alpha emission line, or how the LABs are connected to the surrounding galaxies. Lyman-alpha blobs may hold valuable clues to determine how galaxies are formed. The most massive Lyman-alpha blobs have been discovered by Tristan Friedrich et al. (2021), Steidel et al. (2000), Francis et al. (2001), Matsuda et al. (2004), Dey et al. (2005), Nilsson et al. (2006), and Smith & Jarvis et al. (2007).

Examples

Himiko , also known as the , was a shamaness-queen of Yamatai-koku in . Early Chinese dynastic histories chronicle tributary relations between Queen Himiko and the Cao Wei Kingdom (220–265) and record that the Yayoi period people chose her as ruler ...

* LAB-1 * EQ J221734.0+001701, the ''SSA22 Protocluster'' * Ton 618, hyperluminous quasar powering a Lyman-alpha blob; also possesses one of the most massive black holes known.

Notes

{{Nebulae Astronomical spectroscopy Intergalactic media Large-scale structure of the cosmos Articles containing video clips

Examples

See also

Notes