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Completata la mappa 3D delle galassie distanti
La survey del VLT mostra la distribuzione nello spazio di 90 000 galassie
15 Dicembre 2016
Nell'arco di quasi otto anni, VIMOS (Visible MultiObject Spectrograph), installato sul VLT (Very Large Telescope) dell’ESO in Cile, ha assemblato un mappa tridimensionale delle galassie presenti in due porzioni del cielo australe. In totale, sono state dedicate 440 ore di osservazione alla misurazione dello spettro di oltre 90 000 galassie distanti, producendo la mappa di una regione del cielo pari a 24 metri quadrati, per una distanza corrispondente all'epoca in cui l'Universo aveva circa metà della sua età attuale [1].
Nel 2013, l'ESO ha comunicato che il team internazionale di astronomi della VIMOS Public Extragalactic Survey (VIPERS) aveva raccolto dati per circa il 60% delle galassie oggetto dello studio. Con l'intera serie di osservazioni adesso completata, ci troviamo di fronte alla più grande redshift survey mai effettuata con i telescopi dell’ESO [2], che permette di osservare strutture dell'universo più giovane con una combinazione di dettaglio ed estensione spaziale senza precedenti. Esaminando come le galassie erano distribuite nello spazio alcuni miliardi di anni fa, gli astronomi possono imparare di più sulla distribuzione della materia alle scale più grandi del cosmo, così come sondare ulteriormente l'effetto che la misteriosa energia oscura ha avuto sull'Universo giovane, quando questo ha acquisito alcune delle proprietà che osserviamo oggi.
Utilizzando questi dati unici, gli astronomi stanno già ottenendo nuovi risultati entusiasmanti su come le galassie si siano evolute dal momento in cui l'Universo era molto più giovane e su come ciò si colleghi ai dettagli di strutture a grande scala, come filamenti, ammassi e vuoti. La serie completa dei dati della survey è stata resa pubblica a novembre del 2016 ed è adesso disponibile in formato standard nell’archivio dell’ESO.
Note
[1] La luce ha un limite di velocità finito; perciò, più un oggetto è distante, più tempo necessita la sua luce per giungere fino a noi. Ciò significa che vediamo oggetti distanti come apparivano in tempo remoto.
[2] La luce proveniente da ogni galassia viene separata nei colori che la compongono all’interno dello strumento VIMOS. Un'attenta analisi permette agli astronomi di capire la velocità con cui la galassia si sta allontanando da noi, di solito espressa in termini di redshift, o spostamento verso il rosso. Questo, a sua volta, rivela la distanza della galassia da noi e, quando combinato con la posizione nel cielo, la sua posizione nell'Universo.
Ulteriori informazioni
Il team è composto da astronomi in Italia, Francia, Polonia e Regno Unito. Tutti i dettagli sono disponibili sul sito web di VIPERS.
Links
Contatti
Luigi Guzzo
Dipartimento di Fisica, Università Statale di Milano
& INAF – Osservatorio Astronomico di Brera
Milano, Italy
Mobile: +39 366 773 9704
Email: luigi.guzzo@unimi.it
Peter Grimley
ESO Assistant Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6383
Email: pgrimley@partner.eso.org
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