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Panchromatic Hubble Andromeda Treasury XIII: The Cepheid period-luminosity relation in M31
Dalcanton, J. J.; Wagner-Kaiser, R.; Sarajedini, A. +2 more
Using Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) and Wide Field Camera 3 (WFC3) observations from the Panchromatic Hubble Andromeda Treasury (PHAT), we present new period-luminosity (P-L) relations for Cepheid variables in M31. Cepheids from several ground-based studies are identified in the PHAT photometry to derive new P-L and …
Testing the homogeneity of the Universe using gamma-ray bursts
Li, Ming-Hua; Lin, Hai-Nan
Aims: The discovery of a statistically significant clustering in the distribution of gamma-ray bursts (GRBs) has recently been reported. Given that the cluster has a characteristic size of 2000-3000 Mpc and a redshift between 1.6 ≤ z ≤ 2.1, it has been claimed that this structure is incompatible with the cosmological principle of homogeneity …
New insights from deep VLA data on the potentially recoiling black hole CID-42 in the COSMOS field
Elvis, Martin; Loeb, Abraham; Hallinan, Gregg +12 more
We present deep 3-GHz Karl G. Jansky Very Large Array (VLA) observations of the potentially recoiling black hole CID-42 in the Cosmic Evolution Survey (COSMOS) field. This galaxy shows two optical nuclei in the Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) image and a large velocity offset of ≈1300 km s-1 between the broa…
A kiloparsec-scale internal shock collision in the jet of a nearby radio galaxy
Anderson, Jay; van der Marel, Roeland P.; Sparks, William B. +7 more
Jets of highly energized plasma with relativistic velocities are associated with black holes ranging in mass from a few times that of the Sun to the billion-solar-mass black holes at the centres of galaxies. A popular but unconfirmed hypothesis to explain how the plasma is energized is the `internal shock model', in which the relativistic flow is …
The evolution of the disc variability along the hard state of the black hole transient GX 339-4
Nandra, K.; Ponti, G.; De Marco, B. +1 more
We report on the analysis of hard-state power spectral density function (PSD) of GX 339-4 down to the soft X-ray band, where the disc significantly contributes to the total emission. At any luminosity probed, the disc in the hard state is intrinsically more variable than in the soft state. However, the fast decrease of disc variability as a functi…
Leptonic origin of the 100 MeV γ-ray emission from the Galactic centre
Walter, R.; Chernyakova, M.; Malyshev, D. +1 more
Context. The Galactic centre is a bright γ-ray source with the GeV-TeV band spectrum composed of two distinct components in the 1-10 GeV and 1-10 TeV energy ranges. The nature of these two components is not clearly understood.
Aims: We investigate the γ-ray properties of the Galactic centre to clarify the origin of the observed emission.
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Star formation and quenching among the most massive galaxies at z ∼ 1.7
Berta, S.; Daddi, E.; Rodighiero, G. +5 more
We have conducted a detailed object-by-object study of a mass-complete (M* ≥ 1011 M⊙) sample of 56 galaxies at 1.4 ≤ z ≤ 2 in the Great Observatories Origins Deep Survey-South field, showing that an accurate deblending in 24 µm images is essential to properly assign to each galaxy its own star formation rate …
The Nature and Frequency of Outflows from Stars in the Central Orion Nebula Cluster
O'Dell, C. R.; Henney, W. J.; Ferland, G. J. +3 more
Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbi…
Hubble Space Telescope observations of the Kepler-field cluster NGC 6819 - I. The bottom of the white dwarf cooling sequence
Salaris, M.; Anderson, J.; Milone, A. P. +5 more
We use Hubble Space Telescope (HST) to reach the end of the white dwarf (WD) cooling sequence (CS) in the solar-metallicity open cluster NGC 6819. Our photometry and completeness tests show a sharp drop in the number of WDs along the CS at magnitudes fainter than mF606W = 26.050 ± 0.075. This implies an age of 2.25 ± 0.20 Gyr, consisten…
Upper atmosphere temperature structure at the Venusian terminators: A comparison of SOIR and VTGCM results
Wilquet, V.; Mahieux, A.; Brecht, A. S. +5 more
Venus Express SOIR terminator profiles of CO2 densities and corresponding temperatures have been determined for 132 selected orbits obtained between 2006 and 2013. These recently recalibrated measurements provide temperature profiles at the Venusian terminator over approximately 70-160 km, revealing a striking permanent temperature mini…