The REBELS ALMA Survey: efficient Ly alpha transmission of UV-bright z similar or equal to 7 galaxies from large velocity offsets and broad line widths
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The REBELS ALMA Survey : efficient Ly alpha transmission of UV-bright z similar or equal to 7 galaxies from large velocity offsets and broad line widths. / Endsley, Ryan; Stark, Daniel P.; Bouwens, Rychard J.; Schouws, Sander; Smit, Renske; Stefanon, Mauro; Inami, Hanae; Bowler, Rebecca A. A.; Oesch, Pascal; Gonzalez, Valentino; Aravena, Manuel; da Cunha, Elisabete; Dayal, Pratika; Ferrara, Andrea; Graziani, Luca; Nanayakkara, Themiya; Pallottini, Andrea; Schneider, Raffaella; Sommovigo, Laura; Topping, Michael; van der Werf, Paul; Hutter, Anne.
In: Monthly Notices of the Royal Astronomical Society, Vol. 517, No. 4, 10.11.2022, p. 5642-5659.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The REBELS ALMA Survey
T2 - efficient Ly alpha transmission of UV-bright z similar or equal to 7 galaxies from large velocity offsets and broad line widths
AU - Endsley, Ryan
AU - Stark, Daniel P.
AU - Bouwens, Rychard J.
AU - Schouws, Sander
AU - Smit, Renske
AU - Stefanon, Mauro
AU - Inami, Hanae
AU - Bowler, Rebecca A. A.
AU - Oesch, Pascal
AU - Gonzalez, Valentino
AU - Aravena, Manuel
AU - da Cunha, Elisabete
AU - Dayal, Pratika
AU - Ferrara, Andrea
AU - Graziani, Luca
AU - Nanayakkara, Themiya
AU - Pallottini, Andrea
AU - Schneider, Raffaella
AU - Sommovigo, Laura
AU - Topping, Michael
AU - van der Werf, Paul
AU - Hutter, Anne
PY - 2022/11/10
Y1 - 2022/11/10
N2 - Recent work has shown that UV-luminous reionization-era galaxies often exhibit strong Lyman-alpha emission despite being situated at redshifts where the IGM is thought to be substantially neutral. It has been argued that this enhanced Ly alpha transmission reflects the presence of massive galaxies in overdense regions which power large ionized bubbles. An alternative explanation is that massive galaxies shift more of their Ly alpha profile to large velocities (relative to the systemic redshift) where the IGM damping wing absorption is reduced. Such a mass-dependent trend is seen at lower redshifts, but whether one exists at z similar to 7 remains unclear owing to the small number of existing systemic redshift measurements in the reionization era. This is now changing with the emergence of [C ii]-based redshifts from ALMA. Here, we report MMT/Binospec Ly alpha spectroscopy of eight UV-bright (M-UV similar to -22) galaxies at z similar or equal to 7 selected from the ALMA REBELS survey. We detect Ly alpha in four of eight galaxies and use the [C ii] systemic redshifts to investigate the Ly alpha velocity profiles. The Ly alpha lines are significantly redshifted from systemic (average velocity offset = 223 km s(-1)) and broad (FWHM approximate to 300-650 km s(-1)), with two sources showing emission extending to approximate to 750 km s(-1). We find that the broadest Ly alpha profiles are associated with the largest [C ii] line widths, suggesting a potential link between the Ly alpha FWHM and the dynamical mass. Since Ly alpha photons at high velocities transmit efficiently through the z = 7 IGM, our data suggest that velocity profiles play a significant role in boosting the Ly alpha visibility of the most UV-luminous reionization-era galaxies.
AB - Recent work has shown that UV-luminous reionization-era galaxies often exhibit strong Lyman-alpha emission despite being situated at redshifts where the IGM is thought to be substantially neutral. It has been argued that this enhanced Ly alpha transmission reflects the presence of massive galaxies in overdense regions which power large ionized bubbles. An alternative explanation is that massive galaxies shift more of their Ly alpha profile to large velocities (relative to the systemic redshift) where the IGM damping wing absorption is reduced. Such a mass-dependent trend is seen at lower redshifts, but whether one exists at z similar to 7 remains unclear owing to the small number of existing systemic redshift measurements in the reionization era. This is now changing with the emergence of [C ii]-based redshifts from ALMA. Here, we report MMT/Binospec Ly alpha spectroscopy of eight UV-bright (M-UV similar to -22) galaxies at z similar or equal to 7 selected from the ALMA REBELS survey. We detect Ly alpha in four of eight galaxies and use the [C ii] systemic redshifts to investigate the Ly alpha velocity profiles. The Ly alpha lines are significantly redshifted from systemic (average velocity offset = 223 km s(-1)) and broad (FWHM approximate to 300-650 km s(-1)), with two sources showing emission extending to approximate to 750 km s(-1). We find that the broadest Ly alpha profiles are associated with the largest [C ii] line widths, suggesting a potential link between the Ly alpha FWHM and the dynamical mass. Since Ly alpha photons at high velocities transmit efficiently through the z = 7 IGM, our data suggest that velocity profiles play a significant role in boosting the Ly alpha visibility of the most UV-luminous reionization-era galaxies.
KW - galaxies: evolution
KW - galaxies: high-redshift
KW - dark ages
KW - reionization
KW - first stars
KW - LYMAN-BREAK GALAXIES
KW - STAR-FORMATION RATE
KW - ULTRA-DEEP SURVEY
KW - C II EMISSION
KW - LUMINOSITY FUNCTION
KW - COSMIC REIONIZATION
KW - ACCELERATED REIONIZATION
KW - INTERGALACTIC MEDIUM
KW - ULTRAVIOLET-SPECTRA
KW - INTERSTELLAR-MEDIUM
U2 - 10.1093/mnras/stac3064
DO - 10.1093/mnras/stac3064
M3 - Journal article
VL - 517
SP - 5642
EP - 5659
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 4
ER -
ID: 326729796