Periodic Reporting for period 1 - GALPHYS (Uncovering the inner workings of galaxies at cosmic noon)
Periodo di rendicontazione: 2022-10-01 al 2025-03-31
Lookback studies over the past two decades have assembled a fairly complete census of galaxies over 85% of cosmic time, which is now rapidly extending to even earlier epochs largely thanks to the recently launched James Webb Space Telescope. These surveys established that the bulk of stars, which today reside in massive ellipticals and spirals, formed rapidly at redshift z~1–3. Most of this star formation took place in massive gas-rich, turbulent disks, which already followed tight scaling relations in their global properties, and in which dense bulges, fast growing central black holes, and galactic winds were ubiquitous. The next frontier is to uncover the physical mechanisms inside galaxies that govern the buildup of stars and the emergence of galactic structure. This goal can only be reached by resolving gas motions and distributions on the fundamental physical Toomre scale of ~1 kpc at z≳1, requiring ~25 times sharper views than typically achieved so far. Revolutionary improvements in observing sensitivity and resolution now make this possible: the advent in 2022 of the most advanced near-IR adaptive optics-assisted integral field spectrograph ERIS at the Very Large Telescope. GALPHYS centers on an ambitious 900-hour ERIS Guaranteed Time program, and exploits key synergies with cutting-edge (sub-)millimeter interferometry at IRAM/NOEMA and ALMA, as well as sensitive high-resolution optical to mid-infrared imaging from the Hubble and James Webb space telescopes. GALPHYS will produce breakthroughs in the most important, outstanding issues in galaxy evolution: (1) mass and angular momentum transport, (2) the origin of gas turbulence, (3) the evolution of giant star-forming complexes, and (4) the physics of outflows powered by stellar and AGN feedback.
Activities in the first 30 months of the GALPHYS project focussed on astronomical observations, tools, and scientific analyses based on existing and first new data sets. The ERIS Guaranteed Time progam started and reached 37% completion. ERIS being a new instrument, an important first phase of the project consisted in optimization of the observational strategy and data reduction pipeline to ensure the ambitious GALPHYS observations achieve the full performance required by the science goals, especially with adaptive optics (AO). Available complementary NOEMA, ALMA, Hubble and James Webb space telescopes (HST, JWST) were collected, and efficient procedures were put in place to update this in-house database as new data become available, and to re-reduce them when needed. One of the main analysis tool, the state-of-the-art DYSMALpy kinematic modeling software, was thoroughly tested. Extensive documentation, tutorials, and examples of usage were prepared, and the full package was publicly released on openly accessible platforms. Further developments as part of GALPHYS will be included in future DYSMALpy version releases. Scientific analysis has begun based on the first ERIS data sets, new JWST along with existing HST imaging, and available millimeter interferometry, addressing mainly the goals related to mass and angular momentum transport, the properties of giant star-forming complexes, and gas outflows. Preliminary results showcase the unique capabilities of ERIS in resolving galaxies at z~1–3 and their substructure beyond initial expectations. Stronger synergies have emerged with JWST data in characterizing star-forming complexes and gas transport mechanisms within galaxies, as well as with most recent developments in numerical simulations of galaxy evolution. New observational approaches are being undertaken following the surprising non-detection of galactic-scale outflow signatures in a prime spectral tracer of cold molecular gas from the large pre-NOEMA PHIBSS survey.
The successful demonstration of the outstanding and world-unique capabilities of ERIS+AO will be transformative in the field. For the first time, fully sampled near-diffraction-limited, high spectral resolution observations of galactic substructure at z~1–3, in particular so-called giant star-forming “clumps”, are possible. Our pioneering first datasets of clumps resolve their internal motions on unprecedented scales down to 500–700 pc spatially and ~10-15 km/s in velocity. Together with resolution-matched JWST imaging, all of the clump kinematics, dynamical masses, star formation rates, outflows, and stellar populations can be determined. These measurements provide much needed quantitative constraints to establish the nature and fate of clumps, and their role in galaxy evolution. Expanding on this breakthrough has high priority for the next ERIS observing campaigns.
Following earlier discovery of fast radial gas flows in a few z~1–3 disk galaxies, motivating one of the GALPHYS goals, the recent findings of stellar bars and spiral arms at those epochs in JWST imaging adds impetus to the project. Previously thought to not be able to form or survive in the gas-rich turbulent high-redshift disks, their presence now suggests they could mediate radial gas flows, and opens up new research avenues for GALPHYS. In parallel, recent numerical simulations can also now produce bar and spiral features in young gas-rich disks, and prove to be an important tool to quantify these instabilities and resulting gas flows at early times; collaborative work with theorists is being intensified. The GALPHYS team is in a unique position to establish direct connections between kinematics from ERIS, NOEMA, and ALMA and stellar structure from JWST to study mass and angular momentum transport, with high anticipated impact.
Based on galaxy-integrated millimeter CO line spectra of 150 typical massive star-forming galaxies at z~0.5–2.5 from the NOEMA precursor, the team found no evidence of cold molecular gas outflow signatures. This result has major implications in future searches for the bulk of mass in galactic outflows at high redshift, and the team initiated follow-up searches via tracers of warmer molecular and neutral gas.
The improvements to ERIS observing strategies and data reduction pipeline, and the release of the DYSMALpy modeling tool with uniquely flexible mass modeling and fitting capabilities, represent significant advances that will benefit the wider astronomical community.
Following earlier discovery of fast radial gas flows in a few z~1–3 disk galaxies, motivating one of the GALPHYS goals, the recent findings of stellar bars and spiral arms at those epochs in JWST imaging adds impetus to the project. Previously thought to not be able to form or survive in the gas-rich turbulent high-redshift disks, their presence now suggests they could mediate radial gas flows, and opens up new research avenues for GALPHYS. In parallel, recent numerical simulations can also now produce bar and spiral features in young gas-rich disks, and prove to be an important tool to quantify these instabilities and resulting gas flows at early times; collaborative work with theorists is being intensified. The GALPHYS team is in a unique position to establish direct connections between kinematics from ERIS, NOEMA, and ALMA and stellar structure from JWST to study mass and angular momentum transport, with high anticipated impact.
Based on galaxy-integrated millimeter CO line spectra of 150 typical massive star-forming galaxies at z~0.5–2.5 from the NOEMA precursor, the team found no evidence of cold molecular gas outflow signatures. This result has major implications in future searches for the bulk of mass in galactic outflows at high redshift, and the team initiated follow-up searches via tracers of warmer molecular and neutral gas.
The improvements to ERIS observing strategies and data reduction pipeline, and the release of the DYSMALpy modeling tool with uniquely flexible mass modeling and fitting capabilities, represent significant advances that will benefit the wider astronomical community.