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A [C ii] 158 μm emitter associated with an O i absorber at the end of the reionization epoch

Abstract

The physical and chemical properties of the circumgalactic medium at z 6 have been studied successfully through the absorption in the spectra of background quasi-stellar objects1,2,3. One of the most crucial questions is to investigate the nature and location of the source galaxies that give rise to these early metal absorbers4,5,6. Theoretical models suggest that momentum-driven outflows from typical star-forming galaxies can eject metals into the circumgalactic medium and the intergalactic medium at z = 5–6 (refs. 7,8,9). Deep, dedicated surveys have searched for Lyα emission associated with strong C iv absorbers at z ≈ 6, but only a few Lyα-emitter candidates have been detected. Interpreting these detections is moreover ambiguous because Lyα is a resonant line10,11,12, raising the need for complementary techniques for detecting absorbers’ host galaxies. Here we report a [C ii] 158 μm emitter detected using the Atacama Large Millimeter Array that is associated with a strong low-ionization absorber, O i, at z = 5.978. The projected impact parameter between O i and [C ii] emitter is 20.0 kpc. The measured [C ii] luminosity is 7.0 × 107 solar luminosities. Further analysis indicates that strong O i absorbers may reside in the circumgalactic medium of massive halos one to two orders of magnitude more massive than expected values8,14.

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Fig. 1: ALMA observations.
Fig. 2: Comparison between simulations and observations.
Fig. 3: Comparison of cross-correlation function between simulations and observations.

Data availability

Both ALMA and HST data sets used in this work are publicly available. The data reported in this paper are available through the ALMA archive at https://almascience.eso.org/aq/ with project code 2017.1.01088.S and through the HST archive at https://archive.stsci.edu/hst/ with project codes 15410 and 12974. Other data are available from the corresponding author upon reasonable request.

Code availability

The ALMA data were reduced using the CASA pipeline version 5.4.0, available at https://casa.nrao.edu/casa_obtaining.shtml.

References

  1. Codoreanu, A. et al. The comoving mass density of Mg ii from z ~ 2 to 5.5. Mon. Not. R. Astron. Soc. 472, 1023–1051 (2017).

    ADS  Google Scholar 

  2. Becker, G. D. et al. The evolution of O i over 3.2 < z < 6.5: reionization of the circumgalactic medium. Astrophys. J. 883, 163 (2019).

    ADS  Google Scholar 

  3. Cooper, T. J. et al. Heavy element absorption systems at 5.0 < z < 6.8: metal-poor neutral gas and a diminishing signature of highly ionized circumgalactic matter. Astrophys. J. 882, 77 (2019).

    ADS  Google Scholar 

  4. Cai, Z., Fan, X., Dave, R., Finlator, K. & Oppenheimer, B. Probing the metal enrichment of the intergalactic medium at z = 5–6 using the Hubble Space Telescope. Astrophys. J. Lett. 849, L18 (2017).

    ADS  Google Scholar 

  5. Bielby, R. M. et al. Into the Ly α jungle: exploring the circumgalactic medium of galaxies at z ~ 4–5 with MUSE. Mon. Not. R. Astron. Soc. 493, 5336–5356 (2020).

    ADS  Google Scholar 

  6. Díaz, C. G. et al. Faint LAEs near z > 4.7 C iv absorbers revealed by MUSE. Mon. Not. R. Astron. Soc. 502, 2645–2663 (2021).

    ADS  Google Scholar 

  7. Oppenheimer, B. D., Davé, R. & Finlator, K. Tracing the re-ionization-epoch intergalactic medium with metal absorption lines. Mon. Not. R. Astron. Soc. 396, 729–758 (2009).

    ADS  Google Scholar 

  8. Finlator, K. et al. The host haloes of O i absorbers in the reionization epoch. Mon. Not. R. Astron. Soc. 436, 1818–1835 (2013).

    ADS  Google Scholar 

  9. Finlator, K., Doughty, C., Cai, Z. & Díaz, G. The faint host galaxies of C iv absorbers at z > 5. Mon. Not. R. Astron. Soc. 493, 3223–3237 (2020).

    ADS  Google Scholar 

  10. Dijkstra, M., Haiman, Z. & Spaans, M. Lyα radiation from collapsing protogalaxies. I. Characteristics of the emergent spectrum. Astrophys. J. 649, 14–36 (2006).

    ADS  Google Scholar 

  11. Zheng, Z., Cen, R., Trac, H. & Miralda-Escudé, J. Radiative transfer modeling of Lyα emitters. I. Statistics of spectra and luminosity. Astrophys. J. 716, 574–598 (2010).

    ADS  Google Scholar 

  12. Hayes, M. et al. Escape of about five per cent of Lyman-α photons from high-redshift star-forming galaxies. Nature 464, 562–565 (2010).

    ADS  Google Scholar 

  13. Leung, T. K. D. et al. Predictions of the L[C ii]-SFR and [C ii] luminosity function at the epoch of reionization. Astrophys. J. 905, 102 (2020).

    ADS  Google Scholar 

  14. Keating, L. C., Puchwein, E., Haehnelt, M. G., Bird, S. & Bolton, J. S. Testing the effect of galactic feedback on the IGM at z ~ 6 with metal-line absorbers. Mon. Not. R. Astron. Soc. 461, 606–626 (2016).

    ADS  Google Scholar 

  15. Oh, S. P. Probing the dark ages with metal absorption lines. Mon. Not. R. Astron. Soc. 336, 1021–1029 (2002).

    ADS  Google Scholar 

  16. Furlanetto, S. R. & Loeb, A. Metal absorption lines as probes of the intergalactic medium prior to the reionization epoch. Astrophys. J. 588, 18–34 (2003).

    ADS  Google Scholar 

  17. Becker, G. D., Sargent, W. L. W., Rauch, M. & Calverley, A. P. High-redshift metals. II. Probing reionization galaxies with low-ionization absorption lines at redshift six. Astrophys. J. 735, 93 (2011).

    ADS  Google Scholar 

  18. Vogelsberger, M. et al. Properties of galaxies reproduced by a hydrodynamic simulation. Nature 509, 177–182 (2014).

    ADS  Google Scholar 

  19. Bolton, J. S. et al. The Sherwood simulation suite: overview and data comparisons with the Lyman α forest at redshifts 2 ≤ z ≤ 5. Mon. Not. R. Astron. Soc. 464, 897–914 (2017).

    ADS  Google Scholar 

  20. Bird, S. et al. Damped Lyman α absorbers as a probe of stellar feedback. Mon. Not. R. Astron. Soc. 445, 2313–2324 (2014).

    ADS  Google Scholar 

  21. Uzgil, B. D. et al. The ALMA Spectroscopic Survey in the HUDF: a search for [C ii] emitters at 6 ≤ z ≤ 8. Astrophys. J. 912, 67 (2021).

    ADS  Google Scholar 

  22. Carilli, C. L. & Walter, F. Cool gas in high-redshift galaxies. Annu. Rev. Astron. Astrophys. 51, 105–161 (2013).

    ADS  Google Scholar 

  23. Lagache, G., Cousin, M. & Chatzikos, M. The [CII] 158 μm line emission in high-redshift galaxies. Astron. Astrophys. 609, A130 (2018).

    ADS  Google Scholar 

  24. Wang, R. et al. Star formation and gas kinematics of quasar host galaxies at z ~ 6: new insights from ALMA. Astrophys. J. 773, 44 (2013).

    ADS  Google Scholar 

  25. Schaerer, D. et al. The ALPINE-ALMA [C ii] survey. Little to no evolution in the [C ii]-SFR relation over the last 13 Gyr. Astron. Astrophys. 643, A3 (2020).

    Google Scholar 

  26. Murphy, E. J. et al. Calibrating extinction-free star formation rate diagnostics with 33 GHz free–free emission in NGC 6946. Astrophys. J. 737, 67 (2011).

    ADS  Google Scholar 

  27. Salmon, B. et al. The relation between star formation rate and stellar mass for galaxies at 3.5 ≤ z ≤ 6.5 in CANDELS. Astrophys. J. 799, 183 (2015).

    ADS  Google Scholar 

  28. Ma, X. et al. Simulating galaxies in the reionization era with FIRE-2: galaxy scaling relations, stellar mass functions, and luminosity functions. Mon. Not. R. Astron. Soc. 478, 1694–1715 (2018).

    ADS  Google Scholar 

  29. Yan, L. et al. The ALPINE-ALMA [C II] survey: [C II] 158 μm emission line luminosity functions at z ~ 4–6. Astrophys. J. 905, 147 (2020).

    ADS  Google Scholar 

  30. Smit, R. et al. The star formation rate function for redshift z ~ 4–7 galaxies: evidence for a uniform buildup of star-forming galaxies during the first 3 Gyr of cosmic time. Astrophys. J. 756, 14 (2012).

    ADS  Google Scholar 

  31. Walter, F. et al. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: survey description. Astrophys. J. 833, 67 (2016).

    ADS  Google Scholar 

  32. De Looze, I., Baes, M., Bendo, G. J., Cortese, L. & Fritz, J. The reliability of [C ii] as an indicator of the star formation rate. Mon. Not. R. Astron. Soc. 416, 2712–2724 (2011).

    ADS  Google Scholar 

  33. McMullin, J. P., Waters, B., Schiebel, D., Young, W. & Golap, K. CASA architecture and applications. In Proc. 16th Annual Conference on Astronomical Data Analysis Software and Systems (eds Shaw, R. A. et al.) Vol. 376, 127 (Astronomical Society of the Pacific, 2007).

  34. Marshall, M. A. et al. Limits to rest-frame ultraviolet emission from far-infrared-luminous z 6 quasar hosts. Astrophys. J. 900, 21 (2020).

    ADS  Google Scholar 

  35. Shapley, A. E., Steidel, C. C., Pettini, M. & Adelberger, K. L. Rest-frame ultraviolet spectra of z ~ 3 Lyman break galaxies. Astrophys. J. 588, 65–89 (2003).

    ADS  Google Scholar 

  36. Stefanon, M. et al. CANDELS multi-wavelength catalogs: source identification and photometry in the CANDELS Extended Groth Strip. Astrophys. J. Suppl. Ser. 229, 32 (2017).

    ADS  Google Scholar 

  37. Speagle, J. S., Steinhardt, C. L., Capak, P. L. & Silverman, J. D. A highly consistent framework for the evolution of the star-forming ‘main sequence’ from z ~ 0–6. Astrophys. J. Suppl. Ser. 214, 15 (2014).

    ADS  Google Scholar 

  38. Capak, P. L. et al. Galaxies at redshifts 5 to 6 with systematically low dust content and high [C ii] emission. Nature 522, 455–458 (2015).

    ADS  Google Scholar 

  39. Fujimoto, S. et al. The ALPINE-ALMA [C ii] survey: size of individual star-forming galaxies at z = 4–6 and their extended halo structure. Astrophys. J. 900, 1 (2020).

    ADS  Google Scholar 

  40. Dessauges-Zavadsky, M. et al. The ALPINE-ALMA [C ii] survey. Molecular gas budget in the early Universe as traced by [C ii]. Astron. Astrophys. 643, A5 (2020).

    Google Scholar 

  41. Zanella, A. et al. The [C ii] emission as a molecular gas mass tracer in galaxies at low and high redshifts. Mon. Not. R. Astron. Soc. 481, 1976–1999 (2018).

    ADS  Google Scholar 

  42. Faisst, A. L. et al. ALMA characterizes the dust temperature of z ~ 5.5 star-forming galaxies. Mon. Not. R. Astron. Soc. 498, 4192–4204 (2020).

    ADS  Google Scholar 

  43. Izumi, T. et al. Subaru high-z exploration of low-luminosity quasars (SHELLQs). III. Star formation properties of the host galaxies at z 6 studied with ALMA. Publ. Astron. Soc. Jpn 70, 36 (2018).

    ADS  Google Scholar 

  44. Bertin, E. & Arnouts, S. SExtractor: software for source extraction. Astron. Astrophys. Suppl. Ser. 117, 393–404 (1996).

    ADS  Google Scholar 

  45. Ono, Y. et al. Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV luminosity functions at z ~ 4–7 derived with the half-million dropouts on the 100 deg2 sky. Publ. Astron. Soc. Jpn 70, S10 (2018).

    ADS  Google Scholar 

  46. Bruzual, G. & Charlot, S. Stellar population synthesis at the resolution of 2003. Mon. Not. R. Astron. Soc. 344, 1000–1028 (2003).

    ADS  Google Scholar 

  47. Calzetti, D. et al. The dust content and opacity of actively star-forming galaxies. Astrophys. J. 533, 682–695 (2000).

    ADS  Google Scholar 

  48. Inoue, A. K., Shimizu, I., Iwata, I. & Tanaka, M. An updated analytic model for attenuation by the intergalactic medium. Mon. Not. R. Astron. Soc. 442, 1805–1820 (2014).

    ADS  Google Scholar 

  49. Neeleman, M. et al. [C ii] 158-μm emission from the host galaxies of damped Lyman-alpha systems. Science 355, 1285–1288 (2017).

    ADS  Google Scholar 

  50. Fumagalli, M., O’Meara, J. M., Prochaska, J. X., Rafelski, M. & Kanekar, N. Directly imaging damped Ly α galaxies at z > 2 – III. The star formation rates of neutral gas reservoirs at z ~ 2.7. Mon. Not. R. Astron. Soc. 446, 3178–3198 (2015).

    ADS  Google Scholar 

  51. Loiacono, F. et al. The ALPINE-ALMA [C II] survey. Luminosity function of serendipitous [C II] line emitters at z ~ 5. Astron. Astrophys. 646, A76 (2021).

    Google Scholar 

  52. Steidel, C. C. et al. The structure and kinematics of the circumgalactic medium from far-ultraviolet spectra of z 2–3 galaxies. Astrophys. J. 717, 289–322 (2010).

    ADS  Google Scholar 

  53. Béthermin, M. et al. The ALPINE-ALMA [CII] survey: data processing, catalogs, and statistical source properties. Astron. Astrophys. 643, A2 (2020).

    Google Scholar 

  54. Fujimoto, S. et al. First identification of 10 kpc [C ii] 158 μm halos around star-forming galaxies at z = 5–7. Astrophys. J. 887, 107 (2019).

    ADS  Google Scholar 

  55. Decarli, R. et al. The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: multiband constraints on line-luminosity functions and the cosmic density of molecular gas. Astrophys. J. 902, 110 (2020).

    ADS  Google Scholar 

  56. Aravena, M. et al. The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: search for [C ii] line and dust emission in 6 < z < 8 galaxies. Astrophys. J. 833, 71 (2016).

    ADS  Google Scholar 

  57. González-López, J. et al. The Atacama Large Millimeter/submillimeter Array Spectroscopic Survey in the Hubble Ultra Deep Field: CO emission lines and 3 mm continuum sources. Astrophys. J. 882, 139 (2019).

    ADS  Google Scholar 

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Acknowledgements

Z.C. and Y.W. are supported by the National Key R&D Program of China (grant no. 2018YFA0404503) and the National Science Foundation of China (grant no. 12073014). M.N. acknowledges support from European Research Council advanced grant no. 740246 (Cosmic_Gas). F.W. is thankful for support provided by NASA through the NASA Hubble Fellowship grant no. HST-HF2-51448.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. J.Y. is a Strittmatter Fellow in Steward Observatory, University of Arizona. The F125W and F160W HST observations in the QSO J2054 field were conducted in the HST program (Proposal ID: 15064). We appreciate the principal investigator Caitlin Casey and the team of this program for collecting these data in Cycle 25.

Author information

Authors and Affiliations

Authors

Contributions

Y.W. and Z.C. led the data reduction, pipeline development, analysis and manuscript writing. Z.C., M.N., K.F. and J.X.P. conceived the project and led the telescope proposal. Z.C. is the principal investigator of the ALMA program (Program ID: 2017.1.01088.S). M.N., K.F. and S.Z. all participated in the analysis and data reduction. R.W. and B.H.C.E. helped with checking of the ALMA data reduction and analysis. X.F., L.C.K., F.W., J.Y., J.F.H. and J.W. all helped significantly with the interpretation and commented on the ALMA proposal and the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Zheng Cai.

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The authors declare no competing interests.

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Peer review information Nature Astronomy thanks Matthieu Béthermin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Channel maps in the whole observed field of view.

These channel maps are arranged from -641.281 to + 734.366 km/s. The channel width is set as the same as [CII] intensity map as 344 km/s for each map. The black and dark red cross indicate the position of QSO J2054 and [CII]2054, respectively. The sizes of the synthesized beams are demonstrated in the bottom-left of these panel.

Extended Data Fig. 2 The detailed pixel flux distributions of different Channel maps.

The green lines show the best-fit single-Gaussian models. We regard the single-Gaussian fitted standard deviation (STD) as the noise in these intensity maps.

Extended Data Fig. 3 Different polarization-correlation maps.

Upper panels, The moment-0 and spectrum under XX polarization. The [CII] moment-0 maps is collapsed based on the same emission range as Fig. 1 and shown by the yellow shaded region. The outer contour is at 3σ level, with contours in steps of 1- σ. The 1- σ rms is 2.47 × 10−2 Jy beam−1 km s−1. Dashed lines represent -2σ-level contours. The integral [CII] flux is 0.0768 ± 0.0247 Jy km s−1. The synthesized beams are shown in the bottom-left of each mom-0 map. Lower panels, The results under YY polarization. The integral [CII] flux is 0.0667 ± 0.0254 Jy km s−1, while the 1- σ is 2.54 × 10−2 Jy beam−1 km s−1.

Source data

Extended Data Fig. 4 Multi-exposure observations.

Left panel: The intensity maps of three individual exposures. The integral [CII] fluxes are 0.0935, 0.0786 and 0.0490 Jy beam−1 km s−1. Meanwhile the 1- σ standard deviation are 0.0319, 0.0335, and 0.0269 Jy beam−1 km s−1, respectively. Right panel: The corresponding 1-D spectra of [CII]2054 in the different individual exposure shown in the left. The beam sizes are shown in the bottom-left of each mom-0 map. The yellow shaded region shows the emission range that is used to generate the [C II]moment-0 maps.

Source data

Extended Data Fig. 5 The number of candidates in the deep ASPECS Band-6 datacube.

We found 719 sources having FWHM ≥250 km s−1 in a 4.2 arcmin2 area of the ASPECS survey. In the figure, sources with Full Width Half Maximum (FWHM) between 200 and 500 km s−1 are present. The vertical dashed line represents the FWHM of the single Gaussian fitting of the [CII]2054.

Extended Data Fig. 6 High-resolution HST broad-band images for five different filters.

These images are sorted by the filter central wavelength. From left to right, these images are F606W, F814W, F105W, F125W, and F160W, respectively. Further, different rows represent different continuum sources (as defined in Table 1). The HST photometry is based on apertures with a 0.6 arcsec diameter, as shown by the green and darkgreen circles. The orange (2-5 σ) and darkred contours (2-4 σ) represent the 264GHz-continuum and [CII]-emission regions in the ALMA observations, respectively. We find no continuum emission in the [CII]-emission region of [CII]2054 in all five HST images.

Extended Data Fig. 7 Color-color diagrams used to select galaxies associated with the OI absorber.

The color properties of these sources are calculated under the AB magnitudes. The plotted error bars show the propagated uncertainties based on the 1 σ errors in magnitudes. The continuum sources are plotted in blue circles. The red and dark blue dots represent the color properties of simulated star-forming galaxies at z > 5.5 and z < 4, respectively. High-redshift selection criteria are based on the distribution of these template galaxies and shown in the grey-shaded regions. Left: I - Y vs. V - I two color diagram. In the left panel, we rule out most continuum sources as high-redshift galaxies, except for C1-1 and C5-3. These two galaxies have the same color properties as the simulated high redshift galaxies, and are plotted as a purple and magenta dot. Right: Y - J vs. I - Y two color diagram. In the right panel, we rule out C1-1 and C5-3 as high-redshift candidates. Note QSO J2054-0005 is plotted as a blue-violet star.

Extended Data Fig. 8 The relationship between the projected impact parameters and halo masses of strong OI absorbers in different simulations.

The halo mass of the [CII]2054 is converted directly from the [CII] luminosity to the halo mass relation (Leung et al. 2020). The error bars represent 1-σ uncertainties of the estimated halo mass. In the three top panels, grey dots represent OI absorbers with the REW of 0.12 ± 0.05 Å (consistent with observations). Meanwhile, Red star represents [CII]2054. Bottom panels show the halo mass distribution of different simulations. In the bottom panels, Red arrow shows that the host halo mass of [CII]2054 is one order of magnitude larger than the median value predicted by all of these simulations.

Source data

Source Data Fig. 1

The spectrum of [C ii]2054.

Source Data Extended Data Fig. 3

The spectrum of [C ii]2054 in different polarization correlations.

Source Data Extended Data Fig. 4

The spectrum of [C ii]2054 in different exposures.

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Wu, Y., Cai, Z., Neeleman, M. et al. A [C ii] 158 μm emitter associated with an O i absorber at the end of the reionization epoch. Nat Astron 5, 1110–1117 (2021). https://doi.org/10.1038/s41550-021-01471-4

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