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Stellar Feedback in the ISM revealed by far-IR spectral-imaging. Invited talk.
|Authors:||Goicoechea, Javier R.|
|Citation:||Exploring the Infrared Universe: The Promise of SPICA (2019)|
|Abstract:||Massive stars dominate the injection of radiative and mechanical energy into the ISM through ionizing radiation, stellar winds, supernova explosions, and merger encounters. This energy input shakes the environment, heats the gas, disrupts star-forming molecular clouds, and creates the cloud and intercloud phases of the ISM. Massive stars are born inside dense giant molecular cloud (GMC) cores. Protostars of different masses develop inside these star-forming cores. Their protostellar outflows shock the ambient cloud, heating and compressing the molecular gas around them. Young stellar objects can be detected by the bright far-IR/submm luminosity of their obscured dusty cocoons. Their properties and energetics can be constrained by studying the far-IR high-J CO and H2O line emission, the unambiguous signature of warm shocked gas. On the spatial scales of an entire GMC, however, most of the gas and dust thermal emission do not arise from individual protostars but from the extended cloud component ([Cii]158¿m and [Oi]63¿m being the brightest lines from the neutral ISM). Once a new massive-star cluster is formed, the energy and momentum injected by photoionization, radiation pressure, and stellar winds ionize and erode the natal molecular cloud, creating Hii regions and blowing expanding bubbles. This stellar feedback can thus determine the gas physical conditions on large scales, drive the evolution of the natal cloud itself, and regulate the formation of new stars. Finding observational tracers of these radiative and mechanical feedback processes is crucial not only for Milky Way studies, but also in the general framework of star formation across cosmic time. There, it is not easy - at high-z yet almost impossible - to disentangle where the emission comes from: nuclear outflows, galactic winds, embedded star-forming sites, quiescent molecular clouds, turbulent halos, etc. While the low-energy lines that can be detected from ground-based radio telescopes like ALMA typically trace cold and quiescent gas, the warm gas affected by feedback processes (i.e., heated by strong stellar UV fields, enhanced X-ray dozes, cosmic-ray particles, or affected by shocks and turbulence dissipation) naturally emits at far-IR wavelengths; through a plethora of atomic fine-structure lines (from the neutral and ionized phases of the ISM) and rotationally-exited molecular lines (from CO, H2O, CH+, HD, and other hydrides) that cannot be detected from the ground. These far-IR lines (often the most luminous lines emitted by the ISM of galaxies) prove to be unique diagnostics of the different types of energy and momentum input deposited into the ISM, that is, of the different feedback mechanisms. SPICA¿s exquisite sensitivity for broad-band far-IR multi-line detection will revolutionize our understanding of the stellar feedback processes that operate in the ISM of galaxies and how this connects/regulates their star-forming history. SPICA¿s multi-tracer capabilities will allow us to measure the physical conditions and chemical content of template star-forming regions in the local Universe and, for the first time, to obtain the same kind of quantitative description of the ISM of primitive star-forming galaxies, thus shedding light on their origin and evolution.|
|Description:||The Promise of SPICA, Crete, Greece, 20-23 May 2019|
|Appears in Collections:||(CFMAC-IFF) Comunicaciones congresos|