Galaxy formation and evolution

Abstract:

<jats:title>ABSTRACT</jats:title> <jats:p>Accurate methods for reverberation mapping using photometry are highly sought after since they are inherently less resource intensive than spectroscopic techniques. However, the effectiveness of photometric reverberation mapping for estimating black hole masses is sparsely investigated at redshifts higher than z ≈ 0.04. Furthermore, photometric methods frequently assume a damped random walk (DRW) model, which may not be universally applicable. We perform photometric reverberation mapping using the javelin photometric DRW model for the QSO SDSS-J144645.44+625304.0 at z = 0.351 and estimate the Hβ lag of $65^{+6}_{-1}$ d and black hole mass of $10^{8.22^{+0.13}_{-0.15}}\, \mathrm{M_{\odot }}$. An analysis of the reliability of photometric reverberation mapping, conducted using many thousands of simulated CARMA process light curves, shows that we can recover the input lag to within 6 per cent on average given our target’s observed signal-to-noise of &amp;gt;20 and average cadence of 14 d (even when DRW is not applicable). Furthermore, we use our suite of simulated light curves to deconvolve aliases and artefacts from our QSO’s posterior probability distribution, increasing the signal-to-noise on the lag by a factor of ∼2.2. We exceed the signal-to-noise of the Sloan Digital Sky Survey Reverberation Mapping Project (SDSS-RM) campaign with a quarter of the observing time per object, resulting in a ∼200 per cent increase in signal-to-noise efficiency over SDSS-RM.</jats:p>

Abstract:

We present near-infrared observations of 42 gravitationally lensed galaxies obtained in the framework of the KMOS Lensed Emission Lines and VElocity Review (KLEVER) Survey, a programme aimed at investigating the spatially resolved properties of the ionized gas in 1.2 < z < 2.5 galaxies by means of a full coverage of the YJ, H, and K near-infrared bands. Detailed metallicity maps and gradients are derived for a subsample of 28 galaxies from reconstructed source-plane emission-line maps, exploiting the variety of different emission-line diagnostics provided by the broad wavelength coverage of the survey. About 85per cent of these galaxies are characterized by metallicity gradients shallower than 0.05 dexkpc−1 and 89 per cent are consistent with a flat slope within 3σ (⁠67 per cent within 1σ), suggesting a mild evolution with cosmic time. In the context of cosmological simulations and chemical evolution models, the presence of efficient feedback mechanisms and/or extended star formation profiles on top of the classical ‘inside-out’ scenario of mass assembly is generally required to reproduce the observed flatness of the metallicity gradients beyond z ∼ 1. Three galaxies with significantly (>3σ) ‘inverted’ gradients are also found, showing an anticorrelation between metallicity and star formation rate density on local scales, possibly suggesting recent episodes of pristine gas accretion or strong radial flows in place. Nevertheless, the individual metallicity maps are characterized by a variety of different morphologies, with flat radial gradients sometimes hiding non-axisymmetric variations on kpc scales, which are washed out by azimuthal averages, especially in interacting systems or in those undergoing local episodes of recent star formation.

Abstract:

We investigate the internal dynamics of anisotropic, rotating globular clusters with a multimass stellar population by performing new direct N-body simulations. In addition to the well-known radial mass segregation effect, where heavy stars and stellar remnants sink toward the center of the cluster, we find a mass segregation in the distribution of orbital inclinations as well. This newly discovered anisotropic mass segregation leads to the formation of a disk-like structure of massive objects near the equatorial plane of a rotating cluster. This result has important implications on the expected spatial distribution of black holes in globular clusters.