Search Publications
Evident black hole-bulge coevolution in the distant universe
Alexander, D. M.; Brandt, W. N.; Yang, G. +4 more
Observations in the local universe show a tight correlation between the masses of supermassive black holes (SMBHs; MBH) and host-galaxy bulges (Mbulge), suggesting a strong connection between SMBH and bulge growth. However, direct evidence for such a connection in the distant universe remains elusive. We have studied sample-a…
Stokes inversion based on convolutional neural networks
Asensio Ramos, A.; Díaz Baso, C. J.
Context. Spectropolarimetric inversions are routinely used in the field of solar physics for the extraction of physical information from observations. The application to two-dimensional fields of view often requires the use of supercomputers with parallelized inversion codes. Even in this case, the computing time spent on the process is still very…
Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars
Minezaki, Takeo; Yoshii, Yuzuru; Enya, Keigo +8 more
We present the results of a dust-reverberation survey of quasars at redshifts z < 0.6. We found a delayed response of the K-band flux variation after the optical flux variation in 25 out of 31 targets, and obtained the lag time between them for 22 targets. Combined with the results for nearby Seyfert galaxies, we provide the largest homogeneous…
Quasars as standard candles II. The non-linear relation between UV and X-ray emission at high redshifts
Vignali, C.; Lusso, E.; Salvestrini, F. +2 more
A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in active galactic nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray e…
Binary asteroseismic modelling: isochrone-cloud methodology and application to Kepler gravity mode pulsators
Aerts, C.; Pápics, P. I.; Bowman, D. M. +5 more
The simultaneous presence of variability due to both pulsations and binarity is no rare phenomenon. Unfortunately, the complexities of dealing with even one of these sources of variability individually means that the other signal is often treated as a nuisance and discarded. However, both types of variability offer means to probe fundamental stell…
Probable detection of hydrogen sulphide (H2S) in Neptune's atmosphere
Fletcher, Leigh N.; Bézard, Bruno; Irwin, Patrick G. J. +4 more
Recent analysis of Gemini-North/NIFS H-band (1.45-1.8 µm) observations of Uranus, recorded in 2010, with recently updated line data has revealed the spectral signature of hydrogen sulphide (H2S) in Uranus's atmosphere (Irwin et al., 2018). Here, we extend this analysis to Gemini-North/NIFS observations of Neptune recorded in 2009 …
Optically Faint Massive Balmer Break Galaxies at z > 3 in the CANDELS/GOODS Fields
Barro, Guillermo; Pérez-González, Pablo G.; Eliche-Moral, M. Carmen +7 more
We present a sample of 33 Balmer break galaxies (BBGs) selected as Hubble Space Telescope/F160W dropouts in the deepest CANDELS/GOODS fields (H ≳ 27.3 mag) but relatively bright in Spitzer/IRAC ([3.6], [4.5] < 24.5 mag), implying red colors (median and quartiles: < H-[3.6]> ={3.1}2.83.4 {mag}). Half of these BBGs are…
General Physical Properties of Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies
Ajello, M.; Fabian, A. C.; Brenneman, L. +4 more
We present the results of a detailed multiwavelength study of a sample of 16 narrow-line Seyfert 1 (NLSy1) galaxies known in γ-rays so far. This includes a focused X-ray spectral analysis, to compare them with a more general NLSy1 population, and a broadband spectral energy distribution (SED) modeling considering the leptonic radiative processes t…
A Catalog of Wide Binary and Multiple Systems of Bright Stars from Gaia-DR2 and the Virtual Observatory
Solano, E.; Rodrigo, C.; Jiménez-Esteban, F. M.
Binary and multiple stars have long provided an effective empirical method of testing stellar formation and evolution theories. In particular, the existence of wide binary systems (separations >20,000 au) is particularly challenging to binary formation models as their physical separations are beyond the typical size of a collapsing cloud core (…
Non-LTE chemical abundances in Galactic open and globular clusters
Ting, Yuan-Sen; Kovalev, Mikhail; Rix, Hans-Walter +1 more
Aims: We study the effects of non-local thermodynamic equilibrium (NLTE) on the determination of stellar parameters and abundances of Fe, Mg, and Ti from the medium-resolution spectra of FGK stars.
Methods: We extended the Payne fitting approach to draw on NLTE and LTE spectral models. These were used to analyse the spectra of the Gaia-E…