National Astronomical Observatory of Japan

Marching to the Beat: Subaru’s FMOS Reveals the Well-Orchestrated Growth of Massive Galaxies in the Early Universe

| Science

Using the Fiber Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope, a team of astronomers participating in the Cosmological Evolution Survey (COSMOS) has found that galaxies, over nine billion years ago, provided a nurturing environment for the birth of new stars at remarkable rates while at the same time as orderly as commuters on a typical Tokyo workday. Even at these early times, there are signs of maturation, since the surroundings of massive galaxies were relatively dusty and enriched by heavier elements.

FMOS spectra in the J-band (left panel) and H-band (right panel), each of which filters light so that only specific wavelengths can pass through. The horizontal axis refers to the wavelength direction while the vertical axis indicates individual spectra observed through each fiber. Small blue circles indicate the detection of emission lines (left: Hβ and [OIII]; right: Hα, [NII]). The inset box shows the intensity of the emission lines for one galaxy. The vertical bands indicate the masked regions where bright sky (OH) emissions are prevented from entering science fibers placed on high-redshift galaxies. (Credit: NAOJ)

The scientific paper on which this article is based appears in the Astrophysical Journal Letters published on November 1, 2013. (Koshino et al. 2013, “The FMOS-COSMOS Survey of Star-forming Galaxies at z ~ 1.6. I. Hα-based Star Formation Rates and Dust Extinction”, The Astrophysical Journal Letters, Volume 777, L8)