%0 Generic %1 matthee2017reveals %A Matthee, J. %A Sobral, D. %A Boone, F. %A Röttgering, H. %A Schaerer, D. %A Girard, M. %A Pallottini, A. %A Vallini, L. %A Ferrara, A. %A Darvish, B. %A Mobasher, B. %D 2017 %K CR7 alma dust metallicity %T ALMA reveals metals yet no dust within multiple components in CR7 %U http://arxiv.org/abs/1709.06569 %X We present spectroscopic follow-up observations of CR7 with ALMA, targeted at constraining the infrared (IR) continuum and CII$_158 m$ line-emission at high spatial resolution matched to the HST/WFC3 imaging. CR7 is a luminous Ly$\alpha$ emitting galaxy at $z=6.6$ that consists of three separated UV-continuum components. Our observations reveal several well-separated components of CII emission. The two most luminous components in CII coincide with the brightest UV components (A and B), blue-shifted by $150$ km s$^-1$ with respect to the peak of Ly$\alpha$ emission. Other CII components are observed close to UV clumps B and C and are blue-shifted by $\approx300$ and $\approx80$ km s$^-1$ with respect to the systemic redshift. We do not detect FIR continuum emission due to dust with a 3$\sigma$ limiting luminosity L$_IR (T_d = 35 \, K) < 3.1\times10^10$ L$_ødot$. This allows us to mitigate uncertainties in the dust-corrected SFR and derive SFRs for the three UV clumps A, B and C of 29, 6 and 7 M$_ødot$ yr$^-1$. All clumps have CII luminosities consistent within the scatter observed in the local relation between SFR and L$_\rm CII$, implying that strong Ly$\alpha$ emission does not necessarily anti-correlate with CII luminosity. Combining our measurements with the literature, we show that galaxies with blue UV slopes have weaker CII emission at fixed SFR, potentially due to their lower metallicities and/or higher photoionisation. Comparison with hydrodynamical simulations suggests that CR7's clumps have metallicities of $0.1<Z/Z_ødot<0.2$. The observed ISM structure of CR7 indicates that we are likely witnessing the build up of a central galaxy in the early Universe through complex accretion of satellites.

@misc{matthee2017reveals, abstract = {We present spectroscopic follow-up observations of CR7 with ALMA, targeted at constraining the infrared (IR) continuum and [CII]$_{158 \mu \rm m}$ line-emission at high spatial resolution matched to the HST/WFC3 imaging. CR7 is a luminous Ly$\alpha$ emitting galaxy at $z=6.6$ that consists of three separated UV-continuum components. Our observations reveal several well-separated components of [CII] emission. The two most luminous components in [CII] coincide with the brightest UV components (A and B), blue-shifted by $\approx 150$ km s$^{-1}$ with respect to the peak of Ly$\alpha$ emission. Other [CII] components are observed close to UV clumps B and C and are blue-shifted by $\approx300$ and $\approx80$ km s$^{-1}$ with respect to the systemic redshift. We do not detect FIR continuum emission due to dust with a 3$\sigma$ limiting luminosity L$_{\rm IR} (T_d = 35 \rm \, K) < 3.1\times10^{10}$ L$_{\odot}$. This allows us to mitigate uncertainties in the dust-corrected SFR and derive SFRs for the three UV clumps A, B and C of 29, 6 and 7 M$_{\odot}$ yr$^{-1}$. All clumps have [CII] luminosities consistent within the scatter observed in the local relation between SFR and L$_{\rm [CII]}$, implying that strong Ly$\alpha$ emission does not necessarily anti-correlate with [CII] luminosity. Combining our measurements with the literature, we show that galaxies with blue UV slopes have weaker [CII] emission at fixed SFR, potentially due to their lower metallicities and/or higher photoionisation. Comparison with hydrodynamical simulations suggests that CR7's clumps have metallicities of $0.1<\rm Z/Z_{\odot}<0.2$. The observed ISM structure of CR7 indicates that we are likely witnessing the build up of a central galaxy in the early Universe through complex accretion of satellites.}, added-at = {2017-09-21T10:21:34.000+0200}, author = {Matthee, J. and Sobral, D. and Boone, F. and Röttgering, H. and Schaerer, D. and Girard, M. and Pallottini, A. and Vallini, L. and Ferrara, A. and Darvish, B. and Mobasher, B.}, biburl = {https://www.bibsonomy.org/bibtex/2e60debadf48facced8fe69928bef2b20/miki}, description = {[1709.06569] ALMA reveals metals yet no dust within multiple components in CR7}, interhash = {cb787163a6aaf51264f39560a04248ca}, intrahash = {e60debadf48facced8fe69928bef2b20}, keywords = {CR7 alma dust metallicity}, note = {cite arxiv:1709.06569Comment: 17 pages, submitted to ApJ, comments welcome}, timestamp = {2017-09-21T10:21:34.000+0200}, title = {ALMA reveals metals yet no dust within multiple components in CR7}, url = {http://arxiv.org/abs/1709.06569}, year = 2017 }