TY - JOUR
T1 - Lyα luminosity functions at redshift z ≈ 4.5
AU - Zheng, Zhen Ya
AU - Finkelstein, Steven L.
AU - Finkelstein, Keely
AU - Tilvi, Vithal
AU - Rhoads, James E.
AU - Malhotra, Sangeeta
AU - Wang, Jun Xian
AU - Miller, Neal
AU - Hibon, Pascale
AU - Xia, Lifang
PY - 2013/5
Y1 - 2013/5
N2 - We present a spectroscopically confirmed sample of Lyman α emitting galaxies (LAEs) at z ~ 4.5 in the Extended Chandra Deep Field-South (ECDFS), which we combine with a sample of z ~ 4.5 LAEs from previous narrow-band surveys from the Large Area Lyman Alpha (LALA) survey to build a unified Lyα luminosity function. We spectroscopically observed 64 candidate LAEs in the ECDFS, confirming 46 objects as z ~ 4.5 LAEs based on single-line detections with no continuum emission bluewards of the line, resulting in a Lyα confirmation rate of ~70 per cent. We did not detect significant flux from neither the CIV λ1549Å emission line nor the He II λ1640Å emission line in individual LAE spectra. These lines were also undetected in a co-added spectrum, with the co-added line ratio of He II to Lyα constraining the Population III star formation rate (SFR) to be<0.3 per cent of the total SFR and<1.25 per cent of the observed SFR (both at the 2σ level). We combine the optical spectra with deep X-ray and radio images to constrain the AGN fraction in the sample. Only LAE was detected in both the X-ray and radio, while the other objects remained undetected, even when stacked. The Lyα luminosity functions in our two deepest narrow-band filters in the ECDFS differ at greater than 2σ significance, and the product L*Φ* differs by a factor of >3. Similar luminosity function differences have been used to infer evolution in the neutral gas fraction in the intergalactic medium at z > 6, yet here the difference is likely due to cosmic variance, given that the two samples are from adjoining line-of-sight volumes. Combining our new sample of LAEs with those from previous LALA narrow-band surveys at z=4.5, we obtain one of the best measured Lyα luminosity functions to date, with our sample of over 200 spectroscopically confirmed Lyα galaxies yielding log10(L*) = 42.83 ± 0.06 (erg s-1) and log10(Φ*) = -3.48 ± 0.09 (Mpc-3). We compare our new luminosity function to others from the literature to study the evolution of the Lyα luminosity density at 0 < z<7.We find tentative evidence for evolution in the product L*Φ*, which approximately tracks the cosmic SFR density, but since field-tofield and survey-to-survey variations are in some cases as large as the possible evolution, some caution is needed in interpreting this trend.
AB - We present a spectroscopically confirmed sample of Lyman α emitting galaxies (LAEs) at z ~ 4.5 in the Extended Chandra Deep Field-South (ECDFS), which we combine with a sample of z ~ 4.5 LAEs from previous narrow-band surveys from the Large Area Lyman Alpha (LALA) survey to build a unified Lyα luminosity function. We spectroscopically observed 64 candidate LAEs in the ECDFS, confirming 46 objects as z ~ 4.5 LAEs based on single-line detections with no continuum emission bluewards of the line, resulting in a Lyα confirmation rate of ~70 per cent. We did not detect significant flux from neither the CIV λ1549Å emission line nor the He II λ1640Å emission line in individual LAE spectra. These lines were also undetected in a co-added spectrum, with the co-added line ratio of He II to Lyα constraining the Population III star formation rate (SFR) to be<0.3 per cent of the total SFR and<1.25 per cent of the observed SFR (both at the 2σ level). We combine the optical spectra with deep X-ray and radio images to constrain the AGN fraction in the sample. Only LAE was detected in both the X-ray and radio, while the other objects remained undetected, even when stacked. The Lyα luminosity functions in our two deepest narrow-band filters in the ECDFS differ at greater than 2σ significance, and the product L*Φ* differs by a factor of >3. Similar luminosity function differences have been used to infer evolution in the neutral gas fraction in the intergalactic medium at z > 6, yet here the difference is likely due to cosmic variance, given that the two samples are from adjoining line-of-sight volumes. Combining our new sample of LAEs with those from previous LALA narrow-band surveys at z=4.5, we obtain one of the best measured Lyα luminosity functions to date, with our sample of over 200 spectroscopically confirmed Lyα galaxies yielding log10(L*) = 42.83 ± 0.06 (erg s-1) and log10(Φ*) = -3.48 ± 0.09 (Mpc-3). We compare our new luminosity function to others from the literature to study the evolution of the Lyα luminosity density at 0 < z<7.We find tentative evidence for evolution in the product L*Φ*, which approximately tracks the cosmic SFR density, but since field-tofield and survey-to-survey variations are in some cases as large as the possible evolution, some caution is needed in interpreting this trend.
KW - Galaxies: evolution
KW - Galaxies: high-redshift
KW - Galaxies: luminosity function
KW - Mass function
UR - http://www.scopus.com/inward/record.url?scp=84877819734&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84877819734&partnerID=8YFLogxK
U2 - 10.1093/mnras/stt440
DO - 10.1093/mnras/stt440
M3 - Article
AN - SCOPUS:84877819734
SN - 0035-8711
VL - 431
SP - 3589
EP - 3607
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -