MIDIS: Strong (Hb + [OIII]) and Ha emitters at redshift $z\simeq 7-8$ unveiled with JWST/NIRCam and MIRI imaging in the Hubble eXtreme Deep Field (XDF)

Abstract

We make use of \textit{JWST} medium and broad-band NIRCam imaging, along with ultra-deep MIRI $5.6\mu \mathrm{m}$ imaging, in the Hubble eXtreme Deep Field (XDF) to identify prominent line emitters at $z\simeq 7-8$. Out of a total of 58 galaxies at $z\simeq 7-8$, we find 18 robust candidates ($\simeq$31\%) for (H$\beta$ + [OIII]) emitters, based on their enhanced fluxes in the F430M and F444W filters, with EW${}_0$(H$\beta$ +[OIII]) $\simeq 87-2100$ Å. Among these emitters, 16 lie in the MIRI coverage area and 12 exhibit a clear flux excess at $5.6\mu \mathrm{m}$, indicating the simultaneous presence of a prominent H$\alpha$ emission line with EW${}_0$(H$\alpha$) $\simeq 200-3000$ Å. This is the first time that H$\alpha$ emission can be detected in individual galaxies at $z>7$. The H$\alpha$ line, when present, allows us to separate the contributions of H$\beta$ and [OIII] to the (H$\beta$ +[OIII]) complex, and derive H$\alpha$-based star formation rates (SFRs). We find that in most cases [OIII]/H$\beta >1$. Instead, two galaxies have [OIII]/H$\beta <1$, indicating that the NIRCam flux excess is mainly driven by H$\beta$. This could potentially imply extremely low metallicities. Most prominent line emitters are very young starbursts or galaxies on their way to/from the starburst cloud. They make for a cosmic SFR density $\mathrm{lo}{\mathrm{g}}_{10}({\rho }_{\mathrm{SF}{\mathrm{R}}_{\mathrm{H}\alpha }})\simeq -2.35$, which is about a quarter of the total value ($\mathrm{lo}{\mathrm{g}}_{10}({\rho }_{\mathrm{SF}{\mathrm{R}}_{\mathrm{tot}}})\simeq -1.76$) at $z\simeq 7-8$. Therefore, the strong H$\alpha$ emitters likely had a significant role in reionization.

18 pages, 11 figures. The paper has been accepted for publication in ApJ

References in corpus (35)

• Array Programming with NumPy
• Cosmic Star Formation History
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• H-alpha Observations of a Large Sample of Galaxies at z~2: Implications for Star Formation in High Redshift Galaxies
• New observations of z~7 galaxies: evidence for a patchy reionization
• CEERS Epoch 1 NIRCam Imaging: Reduction Methods and Simulations Enabling Early JWST Science Results
• The ALPINE-ALMA [CII] Survey: The nature, luminosity function and star formation history of dusty galaxies up to z~6
• A JWST/NIRCam Study of Key Contributors to Reionization: The Star-forming and Ionizing Properties of UV-faint $z\sim 7-8$ Galaxies
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• Gaia Data Release 3: Catalogue Validation
• Evolution of the UV LF from z~15 to z~8 Using New JWST NIRCam Medium-Band Observations over the HUDF/XDF
• EIGER II. first spectroscopic characterisation of the young stars and ionised gas associated with strong H$\beta$ and [OIII] line-emission in galaxies at z=5-7 with JWST
• Life beyond 30: probing the -20<M_UV<-17 luminosity function at 8<z<13 with the NIRCam parallel field of the MIRI Deep Survey
• The [OIII]$+$H$\beta$ Equivalent Width Distribution at z$\simeq$7: Implications for the Contribution of Galaxies to Reionization
• The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z=1.5-10 UV-selected Galaxies and the Implied High-Redshift Star Formation History
• A First Look at the Abundance Pattern -- O/H, C/O, and Ne/O -- in $z>7$ Galaxies with JWST/NIRSpec
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• The Physical Conditions of Emission-Line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations
• The time-scales probed by star formation rate indicators for realistic, bursty star formation histories from the FIRE simulations
• A Magnified Compact Galaxy at Redshift 9.51 with Strong Nebular Emission Lines
• The Star Formation Burstiness and Ionizing Efficiency of Low-mass Galaxies
• MOIRCS Deep Survey. VIII. Evolution of Star Formation Activity as a Function of Stellar Mass in Galaxies since z~3
• Physical Characterization of Early Galaxies in the Webb's First Deep Field SMACS J0723.3-7323
• The production of ionizing photons in UV-faint z~3-7 galaxies
• High Equivalent Width of Hα+[N II] Emission in z~8 Lyman-break Galaxies from IRAC 5.8μm Observations: Evidence for Efficient Lyman-continuum Photon production in the Epoch of Re-ionization
• ALMA Lensing Cluster Survey: an ALMA galaxy signposting a MUSE galaxy group at z=4.3 behind 'El Gordo'
• An Hα Impression of Lyα Galaxies at $z\simeq 6$ with Deep JWST/NIRCam Imaging
• Early results from GLASS-JWST. VI: Extreme rest-optical equivalent widths detected in NIRISS Wide Field Slitless Spectroscopy
• Reconstructing the observed ionizing photon production efficiency at z~2 using stellar population models
• Bright Lyman $\alpha$ emitters among Spitzer SMUVS galaxies in the MUSE/COSMOS field
• A First Look into the Nature of JWST/MIRI 7.7 micron Sources from SMACS 0723
• Constraints on Fluctuating Star Formation Rates for Intermediate-mass Galaxies with H$\alpha$ and UV Luminosities

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