Search Publications
Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based principal component analysis
Huang, Y.; Chen, B. -Q.; Wang, C. +16 more
Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archaeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters - effective temperature Teff, surface gravity log g and metallicity [Fe/H], absolute magnitudes MV and MKs<…
The search for multiple populations in Magellanic Cloud clusters - II. The detection of multiple populations in three intermediate-age SMC clusters
Dalessandro, E.; Salaris, M.; Larsen, S. +14 more
This is the second paper in our series about the search for multiple populations in Magellanic Cloud star clusters using the Hubble Space Telescope. Here we report the detection of multiple stellar populations in the colour-magnitude diagrams of the intermediate-age clusters Lindsay 1, NGC 416 and NGC 339. With ages between 6.0 and 7.5 Gyr, these …
The nature of massive transition galaxies in CANDELS, GAMA and cosmological simulations
Papovich, Casey; Barro, Guillermo; Bell, Eric F. +25 more
We explore observational and theoretical constraints on how galaxies might transition between the 'star-forming main sequence' (SFMS) and varying 'degrees of quiescence' out to z = 3. Our analysis is focused on galaxies with stellar mass M* > 1010 M⊙, and is enabled by GAMA and CANDELS observations, a semi-analy…
A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
Maraschi, L.; Covino, S.; Antonelli, L. A. +140 more
It is widely believed that the bulk of the Galactic cosmic rays is accelerated in supernova remnants (SNRs). However, no observational evidence of the presence of particles of PeV energies in SNRs has yet been found. The young historical SNR Cassiopeia A (Cas A) appears as one of the best candidates to study acceleration processes. Between 2014 De…
Observational constraints on the specific accretion-rate distribution of X-ray-selected AGNs
Georgakakis, A.; Salvato, M.; Schulze, A. +5 more
This paper estimates the specific accretion-rate distribution of AGNs using a sample of 4821 X-ray sources from both deep and shallow surveys. The specific accretion-rate distribution is used as a proxy of the Eddington ratio and is defined as the probability of a galaxy with a given stellar mass and redshift hosting an active nucleus with a certa…
Witnessing the growth of the nearest galaxy cluster: thermodynamics of the Virgo Cluster outskirts
Simionescu, A.; Allen, S. W.; Werner, N. +2 more
We present results from Suzaku Key Project observations of the Virgo Cluster, the nearest galaxy cluster to us, mapping its X-ray properties along four long 'arms' extending beyond the virial radius. The entropy profiles along all four azimuths increase with radius, then level out beyond ∼0.5r200, while the average pressure at large rad…
The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation
Alexander, D. M.; Wang, L.; De Zotti, G. +15 more
We investigate the mean star formation rates (SFRs) in the host galaxies of ∼3000 optically selected quasi-stellar objects (QSOs) from the Sloan Digital Sky Survey within the Herschel-ATLAS fields, and a radio-luminous subsample covering the redshift range of z = 0.2-2.5. Using Wide-field Infrared Survey Explorer (WISE) and Herschel photometry (12…
Infrared spectroscopy of eruptive variable protostars from VVV
Minniti, D.; Marocco, F.; Lucas, P. W. +11 more
In a companion work (Paper I), we detected a large population of highly variable Young Stellar Objects (YSOs) in the Vista Variables in the Via Lactea (VVV) survey, typically with class I or flat spectrum spectral energy distributions and diverse light-curve types. Here we present infrared spectra (0.9-2.5 µm) of 37 of these variables, many …
A Measurement of the Galaxy Group-Thermal Sunyaev-Zel'dovich Effect Cross-Correlation Function
Jain, Bhuvnesh; Lidz, Adam; Vikram, Vinu
Stacking cosmic microwave background maps around known galaxy clusters and groups provides a powerful probe of the distribution of hot gas in these systems via the Sunyaev-Zel'dovich (SZ) effect. A stacking analysis allows one to detect the average SZ signal around low-mass haloes, to extend measurements out to large scales and measure the redshif…
A uniform metallicity in the outskirts of massive, nearby galaxy clusters
Simionescu, A.; Allen, S. W.; Werner, N. +2 more
Suzaku measurements of a homogeneous metal distribution of Z ∼ 0.3 Solar in the outskirts of the nearby Perseus cluster suggest that chemical elements were deposited and mixed into the intergalactic medium before clusters formed, likely over 10 billion years ago. A key prediction of this early enrichment scenario is that the intracluster medium in…