3 research outputs found
The European Large Area ISO Survey IX: the 90 micron luminosity function from the Final Analysis sample
We present the 90 micron luminosity function of the Final Analysis of the
European Large Area ISO Survey (ELAIS), extending the sample size of our
previous analysis (paper IV) by about a factor of 4. Our sample extends to
z=1.1, around 50 times the comoving volume of paper IV, and 10^{7.7} <
h^{-2}L/Lsun < 10^{12.5}. From our optical spectroscopy campaigns of the
northern ELAIS 90 mircon survey (7.4 deg^2 in total, to S(90um)>70mJy), we
obtained redshifts for 61% of the sample (151 redshifts) to B<21 identified at
7 microns, 15 microns, 20cm or with bright (B<18.5) optical identifications.
The selection function is well-defined, permitting the construction of the 90
micron luminosity function of the Final Analysis catalogue in the ELAIS
northern fields, which is in excellent agreement with our Preliminary Analysis
luminosity function in the ELAIS S1 field from paper IV. The luminosity
function is also in good agreement with the IRAS-based prediction of Serjeant &
Harrison (2004), which if correct requires luminosity evolution of (1+z)^{3.4
+/- 1.0} for consistency with the source counts. This implies an evolution in
comoving volume averaged star formation rate at z<~1 consistent with that
derived from rest-frame optical and ultraviolet surveys.Comment: MNRAS accepted. 7 pages, 5 figures. Uses BoxedEPS (included
A luminous quasar at a redshift of z = 7.085
The intergalactic medium was not completely reionized until approximately a
billion years after the Big Bang, as revealed by observations of quasars with
redshifts of less than 6.5. It has been difficult to probe to higher redshifts,
however, because quasars have historically been identified in optical surveys,
which are insensitive to sources at redshifts exceeding 6.5. Here we report
observations of a quasar (ULAS J112001.48+064124.3) at a redshift of 7.085,
which is 0.77 billion years after the Big Bang. ULAS J1120+0461 had a
luminosity of 6.3x10^13 L_Sun and hosted a black hole with a mass of 2x10^9
M_Sun (where L_Sun and M_Sun are the luminosity and mass of the Sun). The
measured radius of the ionized near zone around ULAS J1120+0641 is 1.9
megaparsecs, a factor of three smaller than typical for quasars at redshifts
between 6.0 and 6.4. The near zone transmission profile is consistent with a Ly
alpha damping wing, suggesting that the neutral fraction of the intergalactic
medium in front of ULAS J1120+0641 exceeded 0.1.Comment: 5 pages, 4 figures; source data available at
http://astro.ic.ac.uk/~mortlock/ulas_j1120+0641