%0 Generic %1 jiang2020luminous %A Jiang, Linhua %A Cohen, Seth H. %A Windhorst, Rogier A. %A Egami, Eiichi %A Finlator, Kristian %A Schaerer, Daniel %A Sun, Fengwu %D 2020 %K library %T Luminous Lyman-alpha Emitters with Very Blue UV-continuum Slopes at Redshift 5.7 <= z <= 6.6 %U http://arxiv.org/abs/2002.02028 %X We study six luminous Lyman-alpha emitters (LAEs) with very blue rest-frame UV continua at $5.7z 6.6$. These LAEs have previous HST and Spitzer IRAC observations. Combining our newly acquired HST images, we find that their UV-continuum slopes $\beta$ are in a range of $-3.4-2.6$. Unlike previous, tentative detections of $-3$ in photometrically selected, low-luminosity galaxies, our LAEs are spectroscopically confirmed and luminous ($M_UV<-20$ mag). We model their broadband spectral energy distributions (SEDs), and find that two $\beta\simeq-2.6\pm0.2$ galaxies can be well fitted with young and dust-free stellar populations. However, it becomes increasingly difficult to fit bluer galaxies. We explore further interpretations by including non-zero LyC escape fraction $f_esc$, very low metallicities, and/or AGN contributions. Assuming $f_esc\simeq0.2$, we achieve the bluest slopes $\beta\simeq-2.7$ when nebular emission is considered. This can nearly explain the SEDs of two galaxies with $\beta\simeq-2.8$ and --2.9 ($\sigma_\beta=0.15$). Larger $f_esc$ values and very low metallicities are not favored by the strong nebular line emission (evidenced by the IRAC flux) or the observed (IRAC 1 - IRAC 2) color. Finally, we find that the $\beta\simeq-2.9$ galaxy can potentially be well explained by the combination of a very young population with a high $f_\rm esc$ ($\ge0.5$) and an old, dusty population. We are not able to produce two $-3.4 \pm0.4$ galaxies. Future deep spectroscopic observations are needed to fully understand these galaxies.

@misc{jiang2020luminous, abstract = {We study six luminous Lyman-alpha emitters (LAEs) with very blue rest-frame UV continua at $5.7\le z \le 6.6$. These LAEs have previous HST and Spitzer IRAC observations. Combining our newly acquired HST images, we find that their UV-continuum slopes $\beta$ are in a range of $-3.4\le \beta \le -2.6$. Unlike previous, tentative detections of $\beta \simeq -3$ in photometrically selected, low-luminosity galaxies, our LAEs are spectroscopically confirmed and luminous ($M_{\rm UV}<-20$ mag). We model their broadband spectral energy distributions (SEDs), and find that two $\beta\simeq-2.6\pm0.2$ galaxies can be well fitted with young and dust-free stellar populations. However, it becomes increasingly difficult to fit bluer galaxies. We explore further interpretations by including non-zero LyC escape fraction $f_{\rm esc}$, very low metallicities, and/or AGN contributions. Assuming $f_{\rm esc}\simeq0.2$, we achieve the bluest slopes $\beta\simeq-2.7$ when nebular emission is considered. This can nearly explain the SEDs of two galaxies with $\beta\simeq-2.8$ and --2.9 ($\sigma_{\beta}=0.15$). Larger $f_{\rm esc}$ values and very low metallicities are not favored by the strong nebular line emission (evidenced by the IRAC flux) or the observed (IRAC 1 - IRAC 2) color. Finally, we find that the $\beta\simeq-2.9$ galaxy can potentially be well explained by the combination of a very young population with a high $f_{\rm esc}$ ($\ge0.5$) and an old, dusty population. We are not able to produce two $\beta \simeq -3.4 \pm0.4$ galaxies. Future deep spectroscopic observations are needed to fully understand these galaxies.}, added-at = {2020-02-07T05:32:20.000+0100}, author = {Jiang, Linhua and Cohen, Seth H. and Windhorst, Rogier A. and Egami, Eiichi and Finlator, Kristian and Schaerer, Daniel and Sun, Fengwu}, biburl = {https://www.bibsonomy.org/bibtex/253d8fd85c9bff7340910b4c3bc4d7481/gpkulkarni}, description = {Luminous Lyman-alpha Emitters with Very Blue UV-continuum Slopes at Redshift 5.7 <= z <= 6.6}, interhash = {c02db7445203326cbb7aa78ab4183161}, intrahash = {53d8fd85c9bff7340910b4c3bc4d7481}, keywords = {library}, note = {cite arxiv:2002.02028Comment: Published in ApJ on 2020 Feb 1; Authors' version (9 pages); See published version at https://iopscience.iop.org/article/10.3847/1538-4357/ab64ea}, timestamp = {2020-02-07T05:32:20.000+0100}, title = {Luminous Lyman-alpha Emitters with Very Blue UV-continuum Slopes at Redshift 5.7 <= z <= 6.6}, url = {http://arxiv.org/abs/2002.02028}, year = 2020 }