Search Publications
Mid-infrared luminous quasars in the GOODS-Herschel fields: a large population of heavily obscured, Compton-thick quasars at z ≈ 2
Daddi, E.; Elbaz, D.; Alexander, D. M. +10 more
We present the infrared (IR) and X-ray properties of a sample of 33 mid-IR luminous quasars (νL6 µm ≥ 6 × 1044 erg s-1) at redshift z ≈ 1-3, identified through detailed spectral energy distribution analyses of distant star-forming galaxies, using the deepest IR data from Spitzer and Herschel in the GOODS-Hers…
Constraining gravity at the largest scales through CMB lensing and galaxy velocities
Ho, Shirley; Alam, Shadab; Pullen, Anthony R. +1 more
We demonstrate a new method to constrain gravity on the largest cosmological scales by combining measurements of cosmic microwave background (CMB) lensing and the galaxy velocity field. EG is a statistic, constructed from a gravitational lensing tracer and a measure of velocities such as redshift-space distortions (RSD), that can discri…
The deepest X-ray view of high-redshift galaxies: constraints on low-rate black hole accretion
Lehmer, B. D.; Bauer, F. E.; Brandt, W. N. +16 more
We exploit the 7 Ms Chandra observations in the Chandra Deep Field-South (CDF-S), the deepest X-ray survey to date, coupled with CANDELS/GOODS-S data, to measure the total X-ray emission arising from 2076 galaxies at 3.5 ≤ z < 6.5. This aim is achieved by stacking the Chandra data at the positions of optically selected galaxies, reaching effect…
A disc wind interpretation of the strong Fe Kα features in 1H 0707-495
Done, Chris; Takahashi, Tadayuki; Hagino, Kouichi +3 more
1H 0707-495 is the most convincing example of a supermassive black hole with an X-ray spectrum being dominated by extremely smeared, relativistic reflection, with the additional requirement of strongly supersolar iron abundance. However, here we show that the iron features in its 2-10 keV spectrum are rather similar to the archetypal wind dominate…
A free-form prediction for the reappearance of supernova Refsdal in the Hubble Frontier Fields cluster MACSJ1149.5+2223
Broadhurst, Tom; Zheng, Wei; Zitrin, Adi +7 more
The massive cluster MACSJ1149.5+2223(z = 0.544) displays five very large lensed images of a well-resolved spiral galaxy at zspect = 1.491. It is within one of these images that the first example of a multiply lensed supernova (SN) has been detected recently as part of the Grism Lens-Amplified Survey from Space. The depth of this data al…
Bayesian model selection without evidences: application to the dark energy equation-of-state
Hobson, M. P.; Lasenby, A. N.; Hee, S. +1 more
A method is presented for Bayesian model selection without explicitly computing evidences, by using a combined likelihood and introducing an integer model selection parameter n so that Bayes factors, or more generally posterior odds ratios, may be read off directly from the posterior of n. If the total number of models under consideration is speci…
A primordial origin for molecular oxygen in comets: a chemical kinetics study of the formation and survival of O2 ice from clouds to discs
van Dishoeck, E. F.; Walsh, C.; Taquet, V. +1 more
Molecular oxygen has been confirmed as the fourth most abundant molecule in cometary material (O2/H2O ∼ 4 per cent) and is thought to have a primordial nature, I.e. coming from the interstellar cloud from which our Solar system was formed. However, interstellar O2 gas is notoriously difficult to detect and has only…
The evolved-star dust budget of the Small Magellanic Cloud: the critical role of a few key players
Boyer, M. L.; Meixner, M.; Kemper, F. +3 more
The life cycle of dust in the interstellar medium is heavily influenced by outflows from asymptotic giant branch (AGB) and red supergiant (RSG) stars, a large fraction of which is contributed by a few very dusty sources. We compute the dust input to the Small Magellanic Cloud (SMC) by fitting the multi-epoch mid-infrared spectral energy distributi…
Dissecting galaxies: spatial and spectral separation of emission excited by star formation and AGN activity
Kewley, Lisa J.; Juneau, Stéphanie; Davies, Rebecca L. +13 more
The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and active galactic nucleus (AGN) activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra. In this paper, we describe how integral field data can be used to spectrally and s…
Spectral analysis of the XMM-Newton data of GX 339-4 in the low/hard state: disc truncation and reflection
Zdziarski, Andrzej A.; Basak, Rupal
We analyse all available observations of GX 339-4 by XMM-Newton in the hard spectral state. We jointly fit the spectral data by Comptonization and the currently best reflection code, relxill. We consider in detail a contribution from a standard blackbody accretion disc, testing whether its inner radius can be set equal to that of the reflector. Ho…