O buraco do ALMA no Universo
Os eventos ocorridos durante o Big Bang foram tão cataclísmicos que deixaram uma marca indelével no tecido do cosmos. Atualmente podemos detectar essas cicatrizes através da observação da radiação mais antiga do Universo. Tendo sido criada há quase 14 mil milhões de anos, esta radiação — que existe atualmente sob a forma de radiação fraca de microondas e toma o nome de radiação cósmica de fundo (CMB, sigla do inglês para cosmic microwave background) — expandiu-se permeando todo o cosmos e enchendo-o de fotões detectáveis.
A CMB pode ser usada para investigar o cosmos através de um fenómeno chamado efeito Sunyaev-Zel´dovich (SZ), o qual foi observado pela primeira vez há cerca de 30 anos. A CMB detecta-se na Terra, uma vez que os seus fotões, de comprimentos de onda na região das microondas, viajam até nós. Ao longo da sua viagem, os fotões passam através de enxames de galáxias que contêm electrões de alta energia, os quais lhes dão um minúsculo “empurrão” energético. Detectar estes fotões que foram “empurrados” com os nossos telescópios é algo desafiante mas importante — já que estas partículas elementares podem ajudar os astrónomos a compreender algumas das propriedades fundamentais do Universo, tais como a localização e distribuição de enxames de galáxias densos.
Esta imagem mostra as primeiras medições do efeito térmico de Sunyaev-Zel´dovich obtidas com o Atacama Large Millimeter/submillimeter Array (ALMA), no Chile. Os astrónomos combinaram dados das antenas ALMA de 7 e 12 metros de diâmetro, produzindo a imagem mais nítida possível. O alvo foi um dos enxames de galáxias mais massivos conhecido, o RX J1347.5-1145, o qual se pode ver como um “buraco” escuro na imagem. As cores correspondem ao brilho — por outras palavras, ao número de fotões detectado no domínio de comprimentos de onda estudado. Zonas vermelhas, laranja e amarelas são especialmente brilhantes, as cores cyan e verde apresentam um brilho médio e o azul e violeta correspondem a brilho fraco. A distribuição de energia dos fotões da CMB desloca-se e aparece-nos como um decréscimo de temperatura nos comprimentos de onda observado pelo ALMA, daí a zona escura (tons azuis-violetas) observada no local onde se situa o enxame.
Links
Créditos:ALMA (ESO/NAOJ/NRAO)/T. Kitayama (Toho University, Japan)/ESA/Hubble & NASA
Sobre a imagem
| Id: | potw1708a |
| Língua: | pt |
| Tipo: | Observação |
| Data de divulgação: | 20 de Fevereiro de 2017 às 06:00 |
| Tamanho: | 3816 x 3559 px |
Sobre o objeto
| Tipo: | Early Universe : Cosmology |
| Constellation: | Virgo |
Formatos de imagens
Papéis de parede
Coordenadas
| Position (RA): | 13 47 30.65 |
| Position (Dec): | -11° 45' 18.95" |
| Field of view: | 1.91 x 1.78 arcminutes |
| Orientação: | O norte está a 130.7° à direita da vertical |
Cores e filtros
| Banda | Comprimento de onda | Telescópio |
|---|---|---|
| Milímetro 92 GHz | 3.258613 mm | Atacama Large Millimeter/submillimeter Array Band 3 |
| Óptico g | 475 nm | Hubble Space Telescope ACS |
| Óptico B | 435 nm | Hubble Space Telescope ACS |
| Óptico V | 606 nm | Hubble Space Telescope ACS |
| Óptico r | 625 nm | Hubble Space Telescope ACS |
| Óptico i | 775 nm | Hubble Space Telescope ACS |
| Óptico z | 850 nm | Hubble Space Telescope ACS |
| Infravermelho J | 1.1 μm | Hubble Space Telescope WFC3 |
| Infravermelho H short | 1.6 μm | Hubble Space Telescope WFC3 |
| Óptico I | 814 nm | Hubble Space Telescope ACS |
| Infravermelho J | 1.1 μm | Hubble Space Telescope WFC3 |
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