Large millimeter telescope
The Large Millimeter Telescope (LMT), in Spanish Gran Telescopio Milimétrico (GTM), is the largest radio telescope for millimeter waves in the range from 0.85 to 4 mm. It is used to research the cosmic background radiation, the first galaxies, active galactic nuclei, interstellar matter, the formation of stars, the investigation of objects in the solar system and the atmosphere of planets and moons. The telescope is part of the VLBI network in the 3 mm and 1.3 mm wavelength range.
Location
The LMT is located on the 4,580 meter high summit of the extinct Sierra Negra volcano in Puebla , Mexico , around 250 kilometers east of Mexico City , in the vicinity of the Citlaltépetl (Pico de Orizaba) volcano , the highest mountain in Mexico in the Pico de National Park area Orizaba . In winter it has visibility conditions like in Antarctica. In the clear air with mean wind speeds of less than 5 meters per second, the alignment accuracy of the antenna is better than an arc second . The structure can compensate for the influence of wind up to a speed of 10 m / s, 90% of the time the actual wind speed is lower. The radio telescope has a good view of both the northern and southern skies and can therefore for the most part examine the same areas of the sky as the observatories on Mauna Kea and in northern Chile. The site can work with the Atacama Large Millimeter / submillimeter Array .
Technical details and operation
The primary mirror of the parabolic antenna has a diameter of 50 meters, an area of almost 2000 square meters and consists of 180 reflectors. The surface is actively controlled and can be computer-controlled to compensate for deformations caused by gravity, temperature differences and wind with actuators. The surface is specified for a roughness of 75 μm.
The secondary mirror is made of aluminum with a roughness of 30 µm and a diameter of 2.5 m. It is suspended in a hexagonal structure and can be aligned using actuators. The flat tertiary mirror supplies the observation instruments and serves to control the alignment.
The antenna weighs 2500 tons and rests on a 540 cubic meter concrete base. The construction costs were 115 million US dollars or over 90 million euros. The design of the telescope comes from MT Aerospace AG in Mainz, mainly from the German engineer Hans Jürgen Kärcher .
The LMT was officially inaugurated on November 22nd, 2006, and scientific observations were made in 2013. The LMT is planned, built and operated jointly by the Mexican Instituto Nacional de Astrofísica, Óptica y Electrónica and the US University of Massachusetts Amherst . In the first years of operation only a part of the antenna with a diameter of 32 m was usable. The last actuators were installed on December 13, 2017, so that the entire surface of the primary mirror can be used for the first time from 2018.
The control systems and some instruments were tested on the Five College Radio Astronomical Observatory (FCRAO) 14-meter telescope prior to installation in the LMT.
Instruments:
- AzTEC: A 144-pixel camera for the 1.1 mm area. The receiver is cooled to approximately 250 mK with a three-stage helium-3 closed-circuit cooling system. In the initial constellation, the instrument can only cover the inner 32 meters of the primary mirror. The instrument was installed and set up on the James Clerk Maxwell Telescope in 2005 and was then used intensively as a guest instrument in the Atacama Submillimeter Telescope Experiment for two winters from 2007 to 2008 .
- Redshift Search Receiver
- SEQUOIA
Scientific goals
The LMT has a threefold objective: to advance research, train the next generation of scientists and engineers, and develop new technologies.
The LMT can take on a variety of research tasks. One of the most important scientific goals is the exploration of the universe.
- Research into the structures of cosmic background radiation after the Big Bang and thus new knowledge about the universe
- Discovery and exploration of thousands of new infrared galaxies shortly after their formation
- Penetration of clouds of dust that hinder the observation of star formation in distant galaxies
- Analysis of active galactic nuclei , investigation of the interaction between supermassive black holes and the associated galaxies
- Follow-up examination after a recognized gamma-ray flash and explanation of the origin of the heaviest chemical elements
The LMT can also be used to research the Milky Way and the local galactic group
- New insights into the properties and distribution of interstellar matter from which stars are formed
- General elucidation of the processes of star formation.
- Proof of the existence and properties of the supermassive black hole in the center of the Milky Way by providing north and south coverage with unparalleled sensitivity to VLBI measurements
The LMT can also be used for astrobiology and planetary research
- Sufficient sensitivity to search for complex organic molecules in space
- Discovery and description of the gas and dust clouds around stars from which the planets are formed
- Analysis of the chemistry and physics of comets, the primal material from which our solar system was formed
- systematic observation of small bodies in the solar system in the millimeter range, including objects close to the earth, main belt asteroids, centaurs and Kuiper belt objects.
- Investigation of the atmosphere of planets and moons in the solar system
The use of LMT enables the sensitivity of VLBI to be improved by a factor of two to three thanks to the large antenna diameter.
As announced in April 2019, LMT was involved in the sensational first photograph of a black hole in 2017 , as part of the Event Horizon Telescope network .
Web links
Individual evidence
- ↑ LMT - Large Millimeter Telescope Alfonso Serrano. Retrieved January 15, 2018 .
- ↑ a b c The LMT Book, Chapter 1 . ( lmtgtm.org [PDF]).
- ↑ https://www.nature.com/articles/d41586-019-01155-0
Coordinates: 18 ° 59 ′ 9.2 " N , 97 ° 18 ′ 53.4" W.