ALMA:n aukko maailmankaikkeudessa
Tapahtumat alkuräjähdyksen jälkeen olivat niin mullistavia, että ne jättivät pysyvät jäljet kosmoksen kudokseen. Voimme nähdä nämä arvet havaitsemalla maailmankaikkeuden vanhinta valoa. Koska tämä kosmisena taustasäteilynä (CMB, Cosmic Microwave Background) tunnettuna heikkona mikroaaltosäteilynä havaittava valo syntyi lähes 14 miljardia vuotta sitten, se on laajentunut ja täyttää nyt koko kosmoksen havaittavissa olevilla fotoneilla.
CMB:tä voidaan käyttää kosmoksen luotaamiseen niin sanotun Sunyaev-Zel’dovich (SZ) -ilmiön avulla, joka havaittiin ensi kertaa 30 vuotta sitten. Havaitsemme CMB:n täällä Maan päällä, kun sen muodostavat mikroaaltofotonit matkaavat avaruuden halki meille asti. Matkallaan meidän luoksemme ne kulkevat suurienergiaisia elektroneja sisältävien galaksijoukkojen halki. Kyseiset elektronit antavat fotoneille pienen energialisäyksen. Näiden lisäpotkun saaneiden fotonien havaitseminen teleskooppiemme avulla on haastavaa, mutta tärkeää. Ne voivat auttaa tähtitieteilijöitä ymmärtämään eräitä maailmankaikkeuden perustavanlaatuisista ominaisuuksista, kuten tiheiden galaksijoukkojen sijainnin ja jakauman.
Tämä kuva näyttää Chilessä sijaitsevan ALMA:n (Atacama Large Millimeter/submillimeter Array) ensimmäiset termisen Sunyaev-Zel’dovich (SZ) -ilmiön havainnot (sinisellä). Tähtitieteilijät yhdistivät havaintoaineistoa ALMA:n 7 ja 12 metrin antenneista tuottaakseen mahdollisimman terävän kuvan. Kohde oli yksi massiivisimmista tunnetuista galaksijoukoista, RX J1347.5–1145, jonka keskusta näkyy tässä ALMA:lla otetun kuvan pimeässä ”reiässä”. CMB:n fotonien energiajakauma siirtyy ja näkyy lämpötilan laskemisena ALMA:n havaitsemalla aallonpituudella, ja siksi tässä kuvassa galaksijoukon kohdalla havaitaan pimeä läikkä.
Linkit
Oikeudet:ALMA (ESO/NAOJ/NRAO)/T. Kitayama (Toho University, Japan)/ESA/Hubble & NASA
Kuvasta
| Tunnistus: | potw1708a |
| Kieli: | fi |
| Tyyppi: | Havainto |
| Julkaisupäivä: | 20. helmikuuta 2017 6:00 |
| Koko: | 3816 x 3559 px |
Kohteesta
| Tyyppi: | Early Universe : Cosmology |
| Constellation: | Virgo |
Taustakuvat
Koordinaatit
| Position (RA): | 13 47 30.65 |
| Position (Dec): | -11° 45' 18.95" |
| Field of view: | 1.91 x 1.78 arcminutes |
| Suuntaus: | Pohjoinen on 130.7° oikea pystysuuntaan nähden |
Värit ja suotimet
| Kaista | Aallonpituus | Teleskooppi |
|---|---|---|
| Millimetri 92 GHz | 3.258613 mm | Atacama Large Millimeter/submillimeter Array Band 3 |
| Optinen g | 475 nm | Hubble Space Telescope ACS |
| Optinen B | 435 nm | Hubble Space Telescope ACS |
| Optinen V | 606 nm | Hubble Space Telescope ACS |
| Optinen r | 625 nm | Hubble Space Telescope ACS |
| Optinen i | 775 nm | Hubble Space Telescope ACS |
| Optinen z | 850 nm | Hubble Space Telescope ACS |
| Infrapuna J | 1.1 μm | Hubble Space Telescope WFC3 |
| Infrapuna H short | 1.6 μm | Hubble Space Telescope WFC3 |
| Optinen I | 814 nm | Hubble Space Telescope ACS |
| Infrapuna J | 1.1 μm | Hubble Space Telescope WFC3 |
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