Periodic Reporting for period 2 - CosmicWeb (Unravelling the Cosmic Web with fluorescent emission)
Reporting period: 2022-03-01 to 2023-08-31
Our cosmological model predicts that most of the matter in the universe is distributed in a network of filaments - the Cosmic Web – in which galaxies form and evolve. Because most of this material is too diffuse to form stars, its direct imaging has remained elusive for several decades leaving fundamental questions still open, including: what are the morphological and kinematical properties of the Cosmic Web on both small (kpc) and large (Mpc) scales? How do galaxies get their gas from the Cosmic Web?
The CosmicWeb program tackle these questions with an innovative method and technology that allows us to directly detect in emission the gaseous Cosmic Web before the peak of galaxy formation, when the universe is less than 3 billion years old: using bright quasars and galaxies as “cosmic flashlights” to make the gas “fluorescently” glow.
The Program is divided into two, interconnected, main Projects. Project 1 aims at the detection of Cosmic filaments on large scales (Scientific Objective, SO, 1), the study of their relation with galaxies (SO2) and the comparison with models to constrain dark matter properties (SO3). Project 2 aims at the high-spatial resolution study of filaments using non resonant lines such Hydrogen H-alpha in order to reveal their small scale distribution (SO4) and their kinematics compared with galaxies (SO5) to inform new CGM models (SO6). The success of these SOs require: i) deep MUSE observations in order to reveal Cosmic filaments in Ly-alpha emission on large scales, ii) multi wavelength information to detect and study the associated galaxy properties, iii) JWST observation to detect H-alpha emission at high-spatial resolution, and, iv) numerical models on both large and small scales (with different dark matter properties).
The CosmicWeb program tackle these questions with an innovative method and technology that allows us to directly detect in emission the gaseous Cosmic Web before the peak of galaxy formation, when the universe is less than 3 billion years old: using bright quasars and galaxies as “cosmic flashlights” to make the gas “fluorescently” glow.
The Program is divided into two, interconnected, main Projects. Project 1 aims at the detection of Cosmic filaments on large scales (Scientific Objective, SO, 1), the study of their relation with galaxies (SO2) and the comparison with models to constrain dark matter properties (SO3). Project 2 aims at the high-spatial resolution study of filaments using non resonant lines such Hydrogen H-alpha in order to reveal their small scale distribution (SO4) and their kinematics compared with galaxies (SO5) to inform new CGM models (SO6). The success of these SOs require: i) deep MUSE observations in order to reveal Cosmic filaments in Ly-alpha emission on large scales, ii) multi wavelength information to detect and study the associated galaxy properties, iii) JWST observation to detect H-alpha emission at high-spatial resolution, and, iv) numerical models on both large and small scales (with different dark matter properties).
During this period all actions associated with the Scientific Objectives of the Program have been initiated with success and in some cases completed.
The most important result achieved so far has been the discovery of the largest Cosmic Web filaments detected to date in a field called MQN01 centered on a bright distant quasar . This discovery was possible thanks to a deep MUSE mosaic follow-up of 40 hours in a large area around a previously found nebula in a shallower survey. The discovered filaments are exceptional, extending beyond the currently surveyed volume and converging into a massive node of the Cosmic Web close to a large concentration of galaxies and Active Galactic Nuclei (AGN). Tens of galaxies have been found within the filaments providing the ideal laboratory to achieve all the SOs of the program (results to be submitted).
The exceptionality of the discoveries in the MQN01 field allowed the CosmicWeb PI to secure observing time on top facilities for a multi-wavelength campaign which started in 2021, including: i) JWST spectroscopic observations to study the kinematics of filaments and galaxies; ii) ALMA deep observations of molecular gas and dust in galaxies; iii) X-ray observations with Chandra to detect AGN; iv) HST observations to study the morphology of star forming galaxies and their relation with filaments; v) multi-wavelength photometry with the VLT to derive the Star Formation Rate and Stellar Masses of galaxies and study how these depend on the properties of filaments feeding them.
Preliminary results from this multi-wavelength campaign revealed the presence of one of the larges concentration of galaxies ever discovered in the distant universe (results to be submitted) making this a unique field to study the relation between gaseous filaments, galaxies and the environment in which they are born and grow.
Important results have been obtained also on the modelling side. Through the use of state-of-the-art cosmological simulations, a new empirical method has been derived that allows us to derive the mass and environment of the haloes from the observed line emission profiles. This new method (results submitted to a journal), allow us to break the main model degeneracy in order to derive from the detected emission the properties of diffuse gas such as density and temperature. These properties are fundamental in order to understand how galaxy form and grow through intergalactic gas feeding.
The most important result achieved so far has been the discovery of the largest Cosmic Web filaments detected to date in a field called MQN01 centered on a bright distant quasar . This discovery was possible thanks to a deep MUSE mosaic follow-up of 40 hours in a large area around a previously found nebula in a shallower survey. The discovered filaments are exceptional, extending beyond the currently surveyed volume and converging into a massive node of the Cosmic Web close to a large concentration of galaxies and Active Galactic Nuclei (AGN). Tens of galaxies have been found within the filaments providing the ideal laboratory to achieve all the SOs of the program (results to be submitted).
The exceptionality of the discoveries in the MQN01 field allowed the CosmicWeb PI to secure observing time on top facilities for a multi-wavelength campaign which started in 2021, including: i) JWST spectroscopic observations to study the kinematics of filaments and galaxies; ii) ALMA deep observations of molecular gas and dust in galaxies; iii) X-ray observations with Chandra to detect AGN; iv) HST observations to study the morphology of star forming galaxies and their relation with filaments; v) multi-wavelength photometry with the VLT to derive the Star Formation Rate and Stellar Masses of galaxies and study how these depend on the properties of filaments feeding them.
Preliminary results from this multi-wavelength campaign revealed the presence of one of the larges concentration of galaxies ever discovered in the distant universe (results to be submitted) making this a unique field to study the relation between gaseous filaments, galaxies and the environment in which they are born and grow.
Important results have been obtained also on the modelling side. Through the use of state-of-the-art cosmological simulations, a new empirical method has been derived that allows us to derive the mass and environment of the haloes from the observed line emission profiles. This new method (results submitted to a journal), allow us to break the main model degeneracy in order to derive from the detected emission the properties of diffuse gas such as density and temperature. These properties are fundamental in order to understand how galaxy form and grow through intergalactic gas feeding.
The discovery of the Cosmic Web filaments in emission in the MQN01 and its associated galaxy overdensity represent major breakthroughs in the field for at least three reasons: i) they give us the unique opportunity to study the morphology and properties of Cosmic Web filaments in emission on both cosmological scales (several Mpc) with MUSE and small scales (a few kph or smaller) with JWST observations; ii) it is a unique field for which the properties of the filaments, in terms of density distribution, morphology and kinematics, could be correlated to the galaxy properties (e.g. SFR, stellar masses, molecular gas content, orientation, and morphology) on a statistical sample given the large galaxy overdensity; iii) the central regions of the structure represents a unique environment discovered so far at high redshift with the presence of one of the largest overdensity of galaxies and AGN, the likely progenitor of today’s massive galaxy clusters. These unique characteristics will allow us to significantly advance our understanding of the processes regulating structure and galaxy formation and evolution in different environments providing a new laboratory to test new models of both structure and galaxy formation, including the original goal of the program to test dark matter properties.