Abstract
The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z≳7, when galaxies reionized the Universe. Standard models11 predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxies. The raw probability of this happening has been estimated to be ∼0.5 per cent (refs 11, 12), but can be larger owing to observational biases. Here we report that gravitational lensing is likely to dominate the observed properties of galaxies with redshifts of z≳12, when the instrumental limiting magnitude is expected to be brighter than the characteristic magnitude of the galaxy sample. The number counts could be modified by an order of magnitude, with most galaxies being part of multiply imaged systems, located less than 1 arcsec from brighter foreground galaxies at z≈2. This lens-induced association of high-redshift and foreground galaxies has perhaps already been observed among a sample of galaxy candidates identified at z≈10.6. Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 181-184 |
| Number of pages | 4 |
| Journal | Nature |
| Volume | 469 |
| Issue number | 7329 |
| DOIs | |
| State | Published - Jan 13 2011 |
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A distortion of very-high-redshift galaxy number counts by gravitational lensing. / Wyithe, J. Stuart B; Yan, Haojing; Windhorst, Rogier; Mao, Shude.
In: Nature, Vol. 469, No. 7329, 13.01.2011, p. 181-184.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A distortion of very-high-redshift galaxy number counts by gravitational lensing
AU - Wyithe, J. Stuart B
AU - Yan, Haojing
AU - Windhorst, Rogier
AU - Mao, Shude
PY - 2011/1/13
Y1 - 2011/1/13
N2 - The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z≳7, when galaxies reionized the Universe. Standard models11 predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxies. The raw probability of this happening has been estimated to be ∼0.5 per cent (refs 11, 12), but can be larger owing to observational biases. Here we report that gravitational lensing is likely to dominate the observed properties of galaxies with redshifts of z≳12, when the instrumental limiting magnitude is expected to be brighter than the characteristic magnitude of the galaxy sample. The number counts could be modified by an order of magnitude, with most galaxies being part of multiply imaged systems, located less than 1 arcsec from brighter foreground galaxies at z≈2. This lens-induced association of high-redshift and foreground galaxies has perhaps already been observed among a sample of galaxy candidates identified at z≈10.6. Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples.
AB - The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z≳7, when galaxies reionized the Universe. Standard models11 predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxies. The raw probability of this happening has been estimated to be ∼0.5 per cent (refs 11, 12), but can be larger owing to observational biases. Here we report that gravitational lensing is likely to dominate the observed properties of galaxies with redshifts of z≳12, when the instrumental limiting magnitude is expected to be brighter than the characteristic magnitude of the galaxy sample. The number counts could be modified by an order of magnitude, with most galaxies being part of multiply imaged systems, located less than 1 arcsec from brighter foreground galaxies at z≈2. This lens-induced association of high-redshift and foreground galaxies has perhaps already been observed among a sample of galaxy candidates identified at z≈10.6. Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples.
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U2 - 10.1038/nature09619
DO - 10.1038/nature09619
M3 - Article
VL - 469
SP - 181
EP - 184
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7329
ER -