The ALMA REBELS Survey: Specific Star-Formation Rates in the Reionization Era

Abstract

We present specific star-formation rates for 40 UV-bright galaxies at $z\sim 7-8$ observed as part of the Reionization Era Bright Emission Line Survey (REBELS) ALMA large program. The sSFRs are derived using improved measures of SFR and stellar masses, made possible by measurements of far-infrared (FIR) continuum emission and [CII]-based spectroscopic redshifts. For each source in the sample, we derive stellar masses from SED fitting and total SFRs from calibrations of the UV and FIR emission. The median sSFR is $18_{-5}^{+7}$ Gyr${}^{-1}$, significantly larger than literature measurements lacking constraints in the FIR. The increase in sSFR reflects the larger obscured SFRs we derive from the dust continuum relative to that implied by the UV+optical SED. We suggest that such differences may reflect spatial variations in dust across these luminous galaxies, with the component dominating the FIR distinct from that dominating the UV. We demonstrate that the inferred stellar masses (and hence sSFRs) are strongly-dependent on the assumed star formation history (SFH) in reionization-era galaxies. When large sSFR galaxies are modeled with non-parametric SFHs, the derived stellar masses can increase by an order of magnitude relative to constant star formation models, owing to the presence of a significant old stellar population that is outshined by the recent burst. The [CII] line widths in the largest sSFR systems are often very broad, suggesting dynamical masses that are easily able to accommodate the dominant old stellar population suggested by non-parametric models. Regardless of these systematic uncertainties in the derived parameters, we find that the sSFR increases rapidly toward higher redshifts for massive galaxies ($9.6<\log ({\mathrm{M}}_{\ast }/{\mathrm{M}}_{\odot })<9.8$), with a power law that goes as $(1+z{)}^{1.7\pm 0.3}$, broadly consistent with expectations from the evolving baryon accretion rates.

18 pages, 10 figures, submitted to MNRAS

References in corpus (43)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• Dust in the reionization era: ALMA observations of a $z$=8.38 Galaxy
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation
• A lack of evolution in the very bright-end of the galaxy luminosity function from z = 8-10
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• Reionization Era Bright Emission Line Survey: Selection and Characterization of Luminous Interstellar Medium Reservoirs in the z>6.5 Universe
• Star Formation at $4<z<6$ From the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH)
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• Galaxy Stellar Mass Functions from z~10 to z~6 using the Deepest Spitzer/IRAC Data: No Significant Evolution in the Stellar-to-Halo Mass Ratio of Galaxies in the First Gyr of Cosmic Time
• Essential physics of early galaxy formation
• The [OIII]$+$H$\beta$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
• Deep into the structure of the first galaxies: SERRA views
• The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• The ALMA REBELS Survey: Dust Continuum Detections at z > 6.5
• Evidence for a Hard Ionizing Spectrum from a z=6.11 Stellar Population
• The ALPINE-ALMA [CII] survey: Dust attenuation properties and obscured star formation at z~4.4-5.8
• The ALMA REBELS Survey: the dust content of $z\sim 7$ Lyman Break Galaxies
• Are high redshift Galaxies hot? - Temperature of z > 5 Galaxies and Implications on their Dust Properties
• Kinematics of $z\ge 6$ galaxies from [CII] line emission
• The ALMA REBELS Survey. Epoch of Reionization giants: properties of dusty galaxies at $z\approx 7$
• The ALPINE-ALMA [CII] Survey: Obscured Star Formation Rate Density and Main Sequence of star-forming galaxies at z>4
• A survey of high-$z$ galaxies: SERRA simulations
• High star cluster formation efficiency in the strongly lensed Sunburst Lyman-continuum galaxy at z=2.37
• Accurate dust temperature determination in a $z=7.13$ galaxy
• Warm dust in high-z galaxies: origin and implications
• Dust temperature in ALMA $\hbox{[C $\scriptstyle\rm II $]}$-detected high-$z$ galaxies
• Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at $z$$\sim$$7$$-$$8$
• Low-redshift compact star-forming galaxies as analogues of high-redshift star-forming galaxies
• The discovery of rest-frame UV colour gradients and a diversity of dust morphologies in bright z ~ 7 Lyman-break galaxies
• High [OIII]/[CII] surface brightness ratios trace early starburst galaxies
• The ALMA REBELS Survey: The Cosmic HI Gas Mass Density in Galaxies at $z\approx 7$
• The Physical Properties of Luminous $z\gtrsim 8$ Galaxies and Implications for the Cosmic Star Formation Rate Density From $\sim$0.35 deg${}^2$ of (Pure-)Parallel HST Observations
• Blue Rest-Frame UV-Optical Colors in z~8 Galaxies from GREATS: Very Young Stellar Populations at ~650 Myr of Cosmic Time
• AstraeusIV : Quantifying the star formation histories of galaxies in the Epoch of Reionization

Cited by in corpus (50)

• A population of red candidate massive galaxies ~600 Myr after the Big Bang
• A JWST/NIRCam Study of Key Contributors to Reionization: The Star-forming and Ionizing Properties of UV-faint $z\sim 7-8$ Galaxies
• Evolution of the UV LF from z~15 to z~8 Using New JWST NIRCam Medium-Band Observations over the HUDF/XDF
• Searching for Extremely Blue UV Continuum Slopes at $z=7-11$ in JWST/NIRCam Imaging: Implications for Stellar Metallicity and Ionizing Photon Escape in Early Galaxies
• Stochastic star formation in early galaxies: JWST implications
• Star formation histories of UV-luminous galaxies at $z\simeq 6.8$: implications for stellar mass assembly at early cosmic times
• The ALMA REBELS Survey: The Dust-obscured Cosmic Star Formation Rate Density at Redshift 7
• JWST unveils heavily obscured (active and passive) sources up to z~13
• A dormant, overmassive black hole in the early Universe
• Spatially Resolved Properties of High Redshift Galaxies in the SMACS0723 JWST ERO Field
• Blue Monsters. Why are JWST super-early, massive galaxies so blue?
• The UNCOVER Survey: A First-look HST+JWST Catalog of Galaxy Redshifts and Stellar Population Properties Spanning $0.2\lesssim z\lesssim 15$
• ALMA Confirmation of an Obscured Hyperluminous Radio-Loud AGN at $z=6.853$ Associated with a Dusty Starburst in the 1.5 deg${}^2$ COSMOS Field
• The gas and stellar content of a metal-poor galaxy at $z=8.496$ as revealed by JWST and ALMA
• JWST/NIRCam Observations of Stars and HII Regions in $z\simeq 6-8$ Galaxies: Properties of Star Forming Complexes on 150 pc Scales
• JWST reveals a possible $z\sim 11$ galaxy merger in triply-lensed MACS0647$-$JD
• Dusty winds clear JWST super-early galaxies
• The ALMA REBELS Survey: Efficient Ly$\alpha$ Transmission of UV-Bright z$\simeq$7 Galaxies from Large Velocity Offsets and Broad Line Widths
• An empirical study of dust properties at the earliest epochs
• The assembly of dusty galaxies at $z\ge 4$: the build-up of stellar mass and its scaling relations with hints from early JWST data
• Early results from GLASS-JWST. X: Rest-frame UV-optical properties of galaxies at 7 < z < 9
• A lensed protocluster candidate at $z=7.66$ identified in JWST observations of the galaxy cluster SMACS0723-7327
• A needle in a haystack? Catching Pop III stars in the Epoch of Reionization: I. Pop III star forming environments
• A new look at the infrared properties of z $\sim$ 5 galaxies
• Dust attenuation evolution in $z\sim 2$-$12$ JWST galaxies
• The ALMA REBELS Survey: The First Infrared Luminosity Function Measurement at $\mathbf{z \sim 7}
• Dust attenuation law in JWST galaxies at z = 7-8
• Outshining in the Spatially Resolved Analysis of a Strongly-Lensed Galaxy at z=6.072 with JWST NIRCam
• First Light And Reionisation Epoch Simulations (FLARES) VII: The Star Formation and Metal Enrichment Histories of Galaxies in the early Universe
• The ionizing photon production efficiency of bright z$\sim$2-5 galaxies
• The ALMA REBELS Survey: Discovery of a massive, highly star-forming and morphologically complex ULIRG at $z=7.31$
• Synergising semi-analytical models and hydrodynamical simulations to interpret JWST data from the first billion years
• Resolving Ambiguities in the Inferred Star Formation Histories of Intense [O III] Emitters in the Reionisation Era
• Metal and dust evolution in ALMA REBELS galaxies: insights for future JWST observations
• GOODS-ALMA 2.0: Last gigayear star formation histories of the so-called starbursts within the main sequence
• A Dusty Dawn: Galactic Dust Buildup at $z\gtrsim 5$
• Deep Spitzer/IRAC Data for z~10 galaxies Reveal Blue Balmer Break Colors: Young Stellar Populations at ~500 Myr of Cosmic Time
• Dust in High-Redshift Galaxies: Reconciling UV Attenuation and IR Emission
• Cosmic Sands: The Origin of Dusty, Star-forming Galaxies in the Epoch of Reionization
• Carbon envelopes around merging galaxies at z ~ 4.5
• No Need for Extreme Stellar Masses at z~7: A Test-case Study of COS-87259
• The Direct-Method Oxygen Abundance of Typical Dwarf Galaxies at Cosmic High-Noon
• Spatially resolved [CII]-gas conversion factor in early galaxies
• Probing Reionization-Era Galaxies with JWST UV Luminosity Functions and Large-Scale Clustering
• Euclid: Identifying the reddest high-redshift galaxies in the Euclid Deep Fields with gradient-boosted trees
• The ALPINE-ALMA [CII] Survey: Unveiling the baryon evolution in the ISM of $z\sim 5$ star-forming galaxies
• Constraints on dynamically-formed massive black holes in Little Red Dots from X-ray non-detections
• REBELS-IFU: Spatially Resolved Ionizing Photon Production Efficiencies of 12 Bright Galaxies in the Epoch of Reionization
• The slope and scatter of the star forming main sequence at z~5 : reconciling observations with simulations
• Direct detection of cool molecular gas in a star-forming galaxy at $z=7.31$