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Hubble Space Telescope Wfc3 Grism Spectroscopy and Imaging of a Growing Compact Galaxy at Z = 1.9
| Content Provider | Semantic Scholar |
|---|---|
| Author | Brammer, Gabriel |
| Copyright Year | 2010 |
| Abstract | We present HST/WFC3 grism spectroscopy of the brightest gal axy atz > 1.5 in the GOODS-South WFC3 Early Release Science grism pointing, covering the wavelen gth range 0.9μm – 1.7μm. The spectrum is of remarkable quality and shows the redshifted Balmer lines H β, γ, and Hδ in absorption at z = 1.902±0.002, correcting previous erroneous redshift measurements from the rest-frame UV. The average rest-frame equivalent width of the Balmer lines is 8 ű1 Å, which can be produced by a post-starburst stellar popula tion with a luminosity-weighted age of ≈ 0.5 Gyr. TheM/L ratio inferred from the spectrum implies a stellar mass of (4±1)×10M⊙. We determine the morphology of the galaxy from a deep WFC3 H160 image. Similar to other massive galaxies at z ∼ 2 the galaxy is compact, with an effective radius of 2 .1±0.3 kpc. Although most of the light is in a compact core, the galaxy has two red, smooth spir al arms that appear to be tidally-induced. The spatially-resolved spectroscopy demonstrates that the ce nt r of the galaxy is quiescent and the surrounding disk is forming stars, as it shows H β in emission. The galaxy is interacting with a companion at a p rojected distance of 18 kpc, which also shows prominent tidal features. The com panion has a slightly redder spectrum than the primary galaxy but is a factor of ∼ 10 fainter and may have a lower metallicity. It is tempting to interpret these observations as “smoking gun” evidence for the growth of com pact, quiescent high redshift galaxies through minor mergers, which has been proposed by several recent obs ervational and theoretical studies. Interestingly both objects host luminous AGNs, as indicated by their X-ray luminosities, which implies that these mergers can be accompanied by significant black hole growth. This stu dy illustrates the power of moderate dispersion, low background near-IR spectroscopy at HST resolution, whi ch is now available with the WFC3 grism. Subject headings: cosmology: observations — galaxies: evolution — galaxies: formation |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.asu.edu/clas/hst/classes/ast591/VanDokkumBrammer.2010.3446.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Alveolar rhabdomyosarcoma Black Hole Coat of arms Galaxy morphological classification Inference Interaction Luminous Studio Medical Subject Headings Notepad2 Quiesce RADIUS Redshift Stars, Celestial Stellar (payment network) width |
| Content Type | Text |
| Resource Type | Article |
