Search Publications
Chandra and XMM monitoring of the black hole X-ray binary IC 10 X-1
Laycock, Silas G. T.; Cappallo, Rigel C.; Moro, Matthew J.
The massive black hole (BH)+Wolf-Rayet (WR) binary IC 10 X-1 was observed in a series of 10 Chandra and two XMM-Newton observations spanning 2003-2012, showing consistent variability around 7 × 1037 erg s-1, with a spectral hardening event in 2009. We phase connected the entire light curve by folding the photon arrival times …
Radio haloes in Sunyaev-Zel'dovich-selected clusters of galaxies: the making of a halo?
Sommer, M.; Cassano, R.; Vazza, F. +8 more
Radio haloes are synchrotron radio sources detected in some massive galaxy clusters. Their size of Mpc indicates that (re)acceleration processes are taking place in the host cluster. X-ray catalogues of galaxy clusters have been used in the past to search for radio haloes and to understand their connection with cluster-cluster mergers and with the…
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 …
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…
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…
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 …
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…
A double white dwarf with a paradoxical origin?
Gal-Yam, A.; Hermes, J. J.; Gänsicke, B. T. +14 more
We present Hubble Space Telescope UV spectra of the 4.6-h-period double white dwarf SDSS J125733.63+542850.5. Combined with Sloan Digital Sky Survey optical data, these reveal that the massive white dwarf (secondary) has an effective temperature T2 = 13 030 ± 70 ± 150 K and a surface gravity log g2 = 8.73 ± 0.05 ± 0.05 (stati…
Spectral analysis of BD+30°623, the peculiar binary central star of the planetary nebula NGC 1514★
Montesinos, B.; Solano, E.; Ulla, A. +2 more
NGC 1514 is a complex planetary nebula with a peculiar binary central star (BD+30°623) consisting of a cool star and a hot companion. To date, the parameters of the two stars have not been firmly established. We present a detailed spectral analysis of BD+30°623 based on intermediate-resolution Calar Alto Faint Object Spectrograph optical spectra a…
NGC 2276: a remarkable galaxy with a large number of ultraluminous X-ray sources
Wolter, Anna; Esposito, Paolo; Mapelli, Michela +2 more
The starbusting, nearby (D = 32.9 Mpc) spiral (Sc) galaxy NGC 2276 belongs to the sparse group dominated by the elliptical galaxy NGC 2300. NGC 2276 is a remarkable galaxy, as it displays a disturbed morphology at many wavelengths. This is possibly due to gravitational interaction with the central elliptical galaxy of the group. Previous ROSAT and…