Archive for July 13, 2015

A Galaxy at Record Redshift?

Posted in The Universe and Stuff with tags , , , , , on July 13, 2015 by telescoper

Skimming through the arXiv this morning I discovered a paper by Zitrin et al. with the following abstract:

 

abstract_z

I’m not sure if the figures are all significant, but a redshift of z=8.68 makes this the most distant spectroscopically confirmed galaxy on record with a present proper distance of about 9.3 Gpc according to the standard cosmological model, just pipping the previous record holder (whose redshift was in any case disputed). Light from this galaxy has taken about 13.1 Gyr to reach us; that means light set out from it when the Universe was only about 4% of its current age, only about 600 million years after the Big Bang. (Those figures were obtained using the inestimable Ned Wright’s cosmology calculator.)

We are presumably seeing a very young object, in which stars are forming at a considerable rate to account for its brightness. We don’t know exactly when the first stars formed and began to ionize the intergalactic medium, but every time the cosmic distance record is broken we push that time back closer to the Big Bang.

Mind you, I can’t say I’m overwhelmingly convinced by the identification of the redshifted Lyman-α line:

high_zBut what do I know? I’m a theorist whose suspicious of data. Any observers care to comment?

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Awaiting The Barbarians

Posted in Finance, Poetry, Politics with tags , , , , , on July 13, 2015 by telescoper

— Why are we come together in the market place?
 
            Barbarians are expected here to-day.
 
— Why in the Senate-house this inactivity —
why sit the Senators and do not legislate?
 
            Because barbarians are to come to-day
            What laws should they make now — the Senators?
            Presently the barbarians will make laws.
 
— Why has our Emperor risen close upon the sun —
why is he waiting there, by the main city-gates,
seated upon the throne, — august, wearing the crown?
 
            Because barbarians are to come to-day
            And so the Emperor in person waits
            to greet their leader. He has even prepared
            a title-deed, on skin of Pergamus,
            in favour of this leader. It confers
            high rank on the barbarian, many names.
 
— Why do our consuls and the praetors go about
in scarlet togas fretted with embroidery;
why are they wearing bracelets rife with amethysts,
and rings magnificent with glowing emeralds;
why are they holding those invaluable staffs
inlaid so cunningly with silver and with gold?
 
            Because barbarians are to come to-day;
            and the barbarians marvel at such things.
 
— Why come not, as they use, our able orators
to hold forth in their rhetoric, to have their say?
 
            Because barbarians are to come to-day;
            and the barbarians have no taste for words.
 
— Why this confusion all at once, and nervousness:
(how serious of a sudden the faces have become):
why are the streets and meeting-places emptying,
and all the people lost in thought as they turn home?
 
            Because the daylight fails, and the night comes,
            but the barbarians come not. And there be
            who from the frontier have arrived and said
            there are no barbarians any longer.

And now what shall become of us without barbarians?
These people were in sooth some sort of settlement.

by C.P. Cavafy (1863-1933); posted on the occasion of the all-night negotiations between the EU and Greece over a bailout deal.