The Evolution of Spiral Galaxies is Now Reexamined

Previous research on the evolution and formation of spiral galaxies have followed a wrong assumption, according to a team of researchers of Instituto de Astrofisica e Ciencias do Espaco (IA).

Most spiral galaxies are defined by a disc, in which stars, gas, and dust spread out in a specific pattern of bent spiral arms, and a bright central region dubbed the bulge. When analyzing how galaxies evolve and form, it is essential to differentiate between these two elements. 

But all of that represents a scientific challenge, and other studies have traditionally found that the disc brightness expands exponentially to the galactic core. A recent study, however, says otherwise. Here is what you need to know.

Spiral Galaxies: Could They Be Finally Understood?

A recent study about the formation and evolution of spiral galaxies aims to change many scientists’ views and shed some light on previous findings. 

At IA, the team of researchers used a new method to divide the bulge from the disc applied to 135 spiral galaxies from the CALIFA survey. They discovered a lesser contribution of stars from the disk to the overall illumination of the galaxy center. The researchers detailed how such a thing has broad implications for studies on galaxy evolution and formation. 

Furthermore, the team realized a new spectrophotometric bulge-disc decomposition method that mixes advanced spectral synthesis and surface photometry tools, the FADO, and iFIT devices. Then, this technique was used to determine the disc’s maximum contribution to the extent of the bulge. 

The results include that in almost one-third of spiral galaxies, the disc underneath the bulge doesn’t maintain its exponential profile. It shows, however, a substantial decrease or even a central flattening. 

Suppose such findings are going to be confirmed. In that case, this will imply that the relative amount supplied from disc and bulge stars to the galaxy center is distinct from previously shown in a substantial number of studies that found an exponential increase to the center of the disc. 

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