Bibcode
Magliocchetti, M.; Santini, P.; Rodighiero, G.; Grazian, A.; Aussel, H.; Altieri, B.; Andreani, P.; Berta, S.; Cepa, J.; Castañeda, H.; Cimatti, A.; Daddi, E.; Elbaz, D.; Genzel, R.; Gruppioni, C.; Lutz, D.; Magnelli, B.; Maiolino, R.; Popesso, P.; Poglitsch, A.; Pozzi, F.; Sanchez-Portal, M.; Förster Schreiber, N. M.; Sturm, E.; Tacconi, L.; Valtchanov, I.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 416, Issue 2, pp. 1105-1117.
Advertised on:
9
2011
Citations
29
Refereed citations
29
Description
This paper presents the first direct estimate of the 3D clustering
properties of far-infrared sources up to z˜ 3. This has been
possible thanks to the PACS Evolutionary Probe (PEP) survey of the
GOODS-South field performed with the PACS instrument on board the
Herschel satellite. 550 and 502 sources were detected respectively in
the 100- and 160-μm channels down to fluxes ? mJy and ? mJy, cuts
that ensure >80 per cent completeness of the two catalogues. More
than 65 per cent of these sources have an (either photometric or
spectroscopic) redshift determination from the MUSIC catalogue; this
percentage rises to ˜95 per cent in the inner portion of
GOODS-South which is covered by data at other wavelengths. An analysis
of the deprojected two-point correlation function w(θ) over the
whole redshift range spanned by the data reports for the (comoving)
correlation length, r0˜ 6.3 and ˜6.7 Mpc,
respectively at 100 and 160 μm, corresponding to dark matter halo
masses M≳ 1012.4 M&sun;, in an excellent
agreement with previous estimates obtained for mid-IR selected sources
in the same field. Objects at z˜ 2 instead seem to be more
strongly clustered, with r0˜ 19 and ˜17 Mpc in
the two considered PACS channels. This dramatic increase of the
correlation length between z˜ 1 and ˜2 is connected with the
presence, more visible at 100 μm than in the other band, of a wide
(at least 4 Mpc across in projection), M≳ 1014
M&sun;, filamentary structure which includes more than 50 per
cent of the sources detected at z˜ 2. An investigation of the
properties of such sources indicates the possibility of a boosted
star-forming activity in those which reside within the overdense
environment with respect to more isolated galaxies found in the same
redshift range. If confirmed by larger data sets, this result can be
explained as due to the combined effect of large reservoirs of gas
available at high redshifts in deep potential wells such as those
associated with large overdensities and the enhanced rate of encounters
between sources favoured by their relative proximity. Lastly, we also
present our results on the evolution of the relationship between
luminous and dark matter in star-forming galaxies between z˜ 1 and
˜2. We find that the increase in (average) stellar mass in
galaxies between z˜ 1 and ˜2 is about
a factor of 10 lower than that of the dark matter haloes hosting such
objects (z˜
1/z˜ 2˜ 4 ×
10-1 versus Mz˜
1halo/Mhaloz˜ 2˜ 4
× 10-2). When compared with recent results taken from
the literature, our findings agree with the evolutionary picture of
downsizing whereby massive galaxies at z˜ 2 were more actively
forming stars than their z˜ 1 counterparts, while at the same time
they contained a lower fraction of their mass in the form of luminous
matter. Herschel is an ESA space observatory with science instruments
provided by the European-led Principal Investigator consortia, with an
important participation from NASA.
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