1. Unveiling In-Situ Spheroid Formation in Distant, Submillimeter-Bright Galaxies
- Author
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Tan, Qing-Hua, Daddi, Emanuele, Magnelli, Benjamin, Correa, Camila A., Bournaud, Frédéric, Adscheid, Sylvia, Zhang, Shao-Bo, Elbaz, David, Gómez-Guijarro, Carlos, Kalita, Boris S., Liu, Daizhong, Liu, Zhaoxuan, Pety, Jérôme, Puglisi, Annagrazia, Schinnerer, Eva, Silverman, John D., and Valentino, Francesco
- Subjects
Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The majority of stars in today's Universe reside within spheroids, which are bulges of spiral galaxies and elliptical galaxies. Their formation is still an unsolved problem. Infrared/submm-bright galaxies at high redshifts have long been suspected to be related to spheroids formation. Proving this connection has been hampered so far by heavy dust obscuration when focusing on their stellar emission or by methodologies and limited signal-to-noise ratios when looking at submm wavelengths. Here we show that spheroids are directly generated by star formation within the cores of highly luminous starburst galaxies in the distant Universe. This follows from the ALMA submillimeter surface brightness profiles which deviate significantly from those of exponential disks, and from the skewed-high axis-ratio distribution, both derived with a novel analysis technique. These galaxies are fully triaxial rather than flat disks: scale-height ratios are 0.5 on average and $>0.6$ for most spatially compact systems. These observations, supported by simulations, reveal a cosmologically relevant pathway for in-situ spheroid formation through starbursts likely preferentially triggered by interactions (and mergers) acting on galaxies fed by non co-planar gas accretion streams., Comment: Resubmitted to Nature after replying to the first round of referee reports
- Published
- 2024