[Paper Review] A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): JWST Reveals a Filamentary Structure around a z=6.61 Quasar

Feige Wang, Jinyi Yang+57 more|arXiv (Cornell University)|Apr 19, 2023

Galaxies: Formation, Evolution, Phenomena4 citations

TL;DR

Using JWST/NIRCam observations, the ASPIRE survey detects a filamentary structure of star-forming galaxies around a z=6.61 quasar, revealing two overdensities at z=5.4 and z=6.2, with 31 [O III] emitters identified. The findings indicate that high-redshift [O III] emitters are strongly clustered and highlight the complex, multi-wavelength environment of early supermassive black holes.

ABSTRACT

We present the first results from the JWST ASPIRE program (A SPectroscopic survey of biased halos In the Reionization Era). This program represents an imaging and spectroscopic survey of 25 reionization-era quasars and their environments by utilizing the unprecedented capabilities of NIRCam Wide Field Slitless Spectroscopy (WFSS) mode. ASPIRE will deliver the largest ($\sim280~{ m arcmin}^2$) galaxy redshift survey at 3-4 $μ$m among JWST Cycle-1 programs and provide extensive legacy values for studying the formation of the earliest supermassive black holes (SMBHs), the assembly of galaxies, early metal enrichment, and cosmic reionization. In this first ASPIRE paper, we report the discovery of a filamentary structure traced by the luminous quasar J0305-3150 and ten [OIII] emitters at $z=6.6$. This structure has a 3D galaxy overdensity of $δ_{ m gal}=12.6$ over 637 cMpc$^3$, one of the most overdense structures known in the early universe, and could eventually evolve into a massive galaxy cluster. Together with existing VLT/MUSE and ALMA observations of this field, our JWST observations reveal that J0305-3150 traces a complex environment where both UV-bright and dusty galaxies are present, and indicate that the early evolution of galaxies around the quasar is not simultaneous. In addition, we discovered 31 [OIII] emitters in this field at other redshifts, $5.3

Motivation & Objective

• To investigate the cosmic environment of the earliest supermassive black holes (SMBHs) at z ≈ 6–7 using deep spectroscopic surveys.
• To characterize the large-scale structure and galaxy population around a high-redshift quasar at z=6.61.
• To determine the clustering properties of high-redshift [O III] emitters and their association with quasar host environments.
• To assess the role of dusty and UV-bright galaxies in the early universe through multi-wavelength observations.
• To evaluate the utility of [O III] emitters as tracers of cosmic structure at the end of the reionization era.

Proposed method

• Conducted deep near-infrared imaging and spectroscopy with JWST/NIRCam to detect faint, high-redshift galaxies around the z=6.61 quasar J0305–3150.
• Identified [O III] emission-line galaxies via narrowband imaging and confirmed redshifts using spectroscopic follow-up.
• Combined data from JWST with archival Hubble and ALMA observations to enable multi-wavelength characterization of galaxy properties.
• Performed photometric and morphological analysis to classify galaxies as dusty star-forming or UV-bright based on SED fitting and SED shapes.
• Used spatial clustering analysis to quantify overdensities of [O III] emitters at z=5.4 and z=6.2 relative to the quasar field.
• Leveraged the Mikulski Archive for Space Telescopes (MAST) and photometric tools (Photutils) for source detection and photometry.

Experimental results

Research questions

• RQ1 What is the large-scale spatial distribution of galaxies around the z=6.61 quasar J0305–3150?
• RQ2 How do the properties of [O III] emitters at z≈5.3–6.7 correlate with the quasar’s environment?
• RQ3 Are high-redshift [O III] emitters clustered around quasars, and what does this imply for their role as cosmic structure tracers?
• RQ4 What is the mix of dusty star-forming galaxies and UV-bright galaxies in the quasar’s immediate vicinity?
• RQ5 How do multi-wavelength observations (JWST, Hubble, ALMA) improve the characterization of early galaxy populations?

Key findings

• A filamentary structure of star-forming galaxies was detected extending from the z=6.61 quasar J0305–3150, indicating a complex, extended environment.
• Thirty-one [O III] emitters were identified at redshifts between 5.3 and 6.7, with half located in two distinct overdensities at z=5.4 and z=6.2.
• The overdensities at z=5.4 and z=6.2 show strong spatial clustering, suggesting that [O III] emitters trace large-scale structure at high redshift.
• The quasar’s environment hosts a diverse galaxy population, including both UV-bright and dusty star-forming galaxies, indicating complex feedback and accretion processes.
• The serendipitous discovery of two overdensities in a single ASPIRE field implies that [O III] emitters are strongly clustered and potentially powerful tracers of early cosmic structures.
• Multi-wavelength data from JWST, Hubble, and ALMA reveal that the quasar’s surroundings are dynamically complex, with significant dust content and ongoing star formation.