2010ApJ...719.1654Y -
Astrophys. J., 719, 1654-1671 (2010/August-3)
Strong field-to-field variation of Lyα nebulae populations at z =~ 2.3.
YANG Y., ZABLUDOFF A., EISENSTEIN D. and DAVE R.
Abstract (from CDS):
Understanding the nature of distant Lyα nebulae, aka "blobs," and connecting them to their present-day descendants requires constraining their number density, clustering, and large-scale environment. To measure these basic quantities, we conduct a deep narrowband imaging survey in four different fields, Chandra Deep Field South (CDFS), Chandra Deep Field North (CDFN), and two COSMOS subfields, for a total survey area of 1.2 deg2. We discover 25 blobs at z = 2.3 with Lyα luminosities of LLyα= (0.7-8)x1043 erg/s and isophotal areas of Aiso= 10-60 \sq\arcsec. The transition from compact Lyα emitters (LAEs; Aiso∼ a few \sq\arcsec) to extended Lyα blobs (Aiso> 10 \sq\arcsec) is continuous, suggesting a single family perhaps governed by similar emission mechanisms. Surprisingly, most blobs (16/25) are in one survey field, the CDFS. The six brightest, largest blobs with LLyα≳ 1.5x1043 erg/s and Aiso> 16 \sq\arcsec lie only in the CDFS. These large, bright blobs have a field-to-field variance of σv≳ 1.5 (150%) about their number density n ∼1.0+1.8–0.6x10–5/Mpc3. This variance is large, significantly higher than that of unresolved LAEs (σv∼ 0.3 or 30%), and can adversely affect comparisons of blob number densities and luminosity functions (LFs) among different surveys. Our deep, blind survey allows us to construct a reliable blob LF. We compare the statistics of our blobs with dark matter halos in a 1 h–1 Gpc cosmological N-body simulation. At z = 2.3, n implies that each bright, large blob could occupy a halo of Mhalo ≳1013 M☉ if most halos have detectable blobs. The predicted variance in n is consistent with that observed and corresponds to a bias of ∼7. Blob halos lie at the high end of the halo mass distribution at z = 2.3 and are likely to evolve into the ∼1014 M☉ halos typical of galaxy clusters today. On larger scales of ∼10 comoving Mpc, blobs cluster where compact LAEs cluster, indicating that blobs lie in coherent, highly overdense structures.
Abstract Copyright:
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Journal keyword(s):
galaxies: formation - galaxies: high-redshift - intergalactic medium
Nomenclature:
Table 3: [YZE2010] CDFS-LABNN (Nos 01-16), [YZE2010] CDFN-LABNN (Nos 01-05), [YZE2010] COSMOS-LABNN (Nos 01-04).
Simbad objects:
32
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