Galaxy formation and evolution

Abstract:

In 1969, Donald Lynden-Bell became the first astrophysicist to suggest that supermassive black holes in the cores of galaxies might generate the profuse energy put out by quasars — the astonishingly luminous distant bodies identified by astronomer Maarten Schmidt earlier that decade. Lynden-Bell proposed that quasars are powered by the release of gravitational energy as material falls into the deep potential well of the black hole, a process that is much more efficient than thermonuclear fusion

Abstract:

The submillimeter galaxy (SMG) HERMES J105751.1+573027 (hereafter HLock01) at z =2.9574 ±0.0001 is one of the brightest gravitationally lensed sources discovered in the Herschel Multi-tiered Extragalactic Survey. Apart from the high flux densities in the far-infrared, it is also extremely bright in the rest-frame ultraviolet (UV), with a total apparent magnitude mUV≃ 19.7 mag. We report here deep spectroscopic observations with the Gran Telescopio Canarias of the optically bright lensed images of HLock01. Our results suggest that HLock01 is a merger system composed of the Herschel-selected SMG and an optically bright Lyman break-like galaxy (LBG), separated by only 3.3 kpc in projection. While the SMG appears very massive (M∗≃ 5 ×1011Mo), with a highly extinguished stellar component (AV≃ 4.3), the LBG is a young, lower-mass (M∗≃ 1 ×1010Mo), but still luminous (10 × LUV∗) satellite galaxy. Detailed analysis of the high signal-to-noise ratio (S/N) rest-frame UV spectrum of the LBG shows complex kinematics of the gas, exhibiting both blueshifted and redshifted absorption components. While the blueshifted component is associated with strong galactic outflows from the massive stars in the LBG, as is common in most star-forming galaxies, the redshifted component may be associated with gas inflow seen along a favorable sightline to the LBG. We also find evidence of an extended gas reservoir around HLock01 at an impact parameter of 110 kpc, through the detection of C ii λλ1334 absorption in the red wing of a bright Lyα emitter at z ≃ 3.327. The data presented here highlight the power of gravitational lensing in high S/N studies to probe deeply into the physics of high-z star-forming galaxies.

Abstract:

We present detailed simulations of integral field spectroscopic observations of a supernova in a host galaxy at z ∼ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, asssisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova Type from spectral features in the supernova spectrum. We find that in a 3 hour observation, covering the near-infrared H and K bands, at a spectral resolving power of ∼3000, and using the 20×20 mas spaxel scale, we can classify supernova Type Ia and their redshift robustly up to 80 days past maximum light (20 days in the supernova rest frame). We show that HARMONI will provide spectra at z ∼ 3 that are of comparable (or better) quality to the best spectra we can currently obtain at z ∼ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.