分类： 天文学 >> 天文学 提交时间： 2023-02-19
Eva Schinnerer
Eric Emsellem
Jonathan D. Henshaw
Daizhong Liu
Sharon E. Meidt
Miguel Querejeta
Florent Renaud
Mattia C. Sormani
Jiayi Sun
Oleg V. Egorov
Kirsten L. Larson
Adam K. Leroy
Erik Rosolowsky
Karin M. Sandstrom
T. G. Williams
Ashley T. Barnes
F. Bigiel
Melanie Chevance
Yixian Cao
Rupali Chandar
摘要： Large-scale bars can fuel galaxy centers with molecular gas, often leading to the development of dense ring-like structures where intense star formation occurs, forming a very different environment compared to galactic disks. We pair ~0.3" (30pc) resolution new JWST/MIRI imaging with archival ALMA CO(2-1) mapping of the central ~5kpc of the nearby barred spiral galaxy NGC1365, to investigate the physical mechanisms responsible for this extreme star formation. The molecular gas morphology is resolved into two well-known bright bar lanes that surround a smooth dynamically cold gas disk (R_gal ~ 475pc) reminiscent of non-star-forming disks in early type galaxies and likely fed by gas inflow triggered by stellar feedback in the lanes. The lanes host a large number of JWST-identified massive young star clusters. We find some evidence for temporal star formation evolution along the ring. The complex kinematics in the gas lanes reveal strong streaming motions and may be consistent with convergence of gas streamlines expected there. Indeed, the extreme line-widths are found to be the result of inter-`cloud' motion between gas peaks; ScousePy decomposition reveals multiple components with line widths of ~ 19km/s and surface densities of ~ 800M_sun/pc^2, similar to the properties observed throughout the rest of the central molecular gas structure. Tailored hydro-dynamical simulations exhibit many of the observed properties and imply that the observed structures are transient and highly time-variable. From our study of NGC1365, we conclude that it is predominantly the high gas inflow triggered by the bar that is setting the star formation in its CMZ.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ashley T. Barnes
Elizabeth J. Watkins
Sharon E. Meidt
Kathryn Kreckel
Mattia C. Sormani
Robin G. Tress
Simon C. O. Glover
Frank Bigiel
Rupali Chandar
Eric Emsellem
Janice C. Lee
Adam K. Leroy
Karin M. Sandstrom
Eva Schinnerer
Erik W. Rosolowsky
Francesco Belfiore
Guillermo Blanc
Mederic Boquien
Jakob S. den Brok
Yixian Cao
摘要： We present a high-resolution view of bubbles within The Phantom Galaxy (NGC 628); a nearby (~10Mpc), star-forming (~2Msun/yr), face-on (i~9deg) grand-design spiral galaxy. With new data obtained as part of the PHANGS-JWST treasury program, we perform a detailed case-study of two regions of interest, one of which contains the largest and most prominent bubble in the galaxy (The Phantom Void; over 1kpc in diameter), and the other being a smaller region that may be the precursor to such a large bubble (The Precursor Phantom Void). When comparing to matched resolution Halpha observations from the Hubble Space Telescope (HST), we see that the ionized gas is brightest in the shells of both bubbles, and is coincident with the youngest (~1Myr) and most massive (~100,000Msun) stellar associations. We also find an older generation (~20Myr) of stellar associations is present within the bubble of The Phantom Void. From our kinematic analysis of the HI, H2 (CO) and HII gas across The Phantom Void, we infer a high expansion speed of around 15 to 50km/s. The large size and high expansion speed of The Phantom Void suggest that the driving mechanism is sustained stellar feedback due to multiple mechanisms, where early feedback first cleared a bubble (as we observe now in The Precursor Phantom Void), and since then SNe have been exploding within the cavity, and have accelerated the shell. Finally, comparison to simulations shows a striking resemblance to our JWST observations, and suggests that such large-scale stellar feedback-driven bubbles should be common within other galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Janice C. Lee
Karin M. Sandstrom
Adam K. Leroy
David A. Thilker
Eva Schinnerer
Erik Rosolowsky
Kirsten L. Larson
Oleg V. Egorov
Thomas G. Williams
Judy Schmidt
Eric Emsellem
Gagandeep S. Anand
Ashley T. Barnes
Francesco Belfiore
Ivana Beslic
Frank Bigiel
Guillermo A. Blanc
Alberto D. Bolatto
Mederic Boquien
Jakob den Brok
摘要： The PHANGS collaboration has been building a reference dataset for the multi-scale, multi-phase study of star formation and the interstellar medium in nearby galaxies. With the successful launch and commissioning of JWST, we can now obtain high-resolution infrared imaging to probe the youngest stellar populations and dust emission on the scales of star clusters and molecular clouds (\sim5-50 pc). In Cycle 1, PHANGS is conducting an 8-band imaging survey from 2-21\mum of 19 nearby spiral galaxies. CO(2-1) mapping, optical integral field spectroscopy, and UV-optical imaging for all 19 galaxies have been obtained through large programs with ALMA, VLT/MUSE, and Hubble. PHANGS-JWST enables a full inventory of star formation, accurate measurement of the mass and age of star clusters, identification of the youngest embedded stellar populations, and characterization of the physical state of small dust grains. When combined with Hubble catalogs of \sim10,000 star clusters, MUSE spectroscopic mapping of \sim20,000 HII regions, and \sim12,000 ALMA-identified molecular clouds, it becomes possible to measure the timescales and efficiencies of the earliest phases of star formation and feedback, build an empirical model of the dependence of small dust grain properties on local ISM conditions, and test our understanding of how dust-reprocessed starlight traces star formation activity, all across a diversity of galactic environments. Here we describe the PHANGS-JWST Treasury survey, present the remarkable imaging obtained in the first few months of science operations, and provide context for the initial results presented in the first series of PHANGS-JWST publications.
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