Search Publications
Variegate galaxy cluster gas content: Mean fraction, scatter, selection effects, and covariance with X-ray luminosity
Andreon, S.; Moretti, A.; Wang, J. +2 more
We use a cluster sample selected independently of the intracluster medium content with reliable masses to measure the mean gas mass fraction and its scatter, the biases of the X-ray selection on gas mass fraction, and the covariance between the X-ray luminosity and gas mass. The sample is formed by 34 galaxy clusters in the nearby (0.050 < z &l…
Multiwavelength variability study and search for periodicity of PKS 1510-089
Tagliaferri, G.; Ghisellini, G.; Pian, E. +14 more
Context. Blazars are the most luminous and variable active galactic nuclei (AGNs). They are thus excellent probes of accretion and emission processes close to the central engine.
Aims: We concentrate here on PKS 1510-089 (z = 0.36), a blazar belonging to the flat-spectrum radio quasar subclass, an extremely powerful gamma-ray source and one o…
Looking at A 0535+26 at low luminosities with NuSTAR
Hailey, Charles J.; Fürst, Felix; Kretschmar, Peter +12 more
We report on two NuSTAR observations of the high-mass X-ray binary
A low upper mass limit for the central black hole in the late-type galaxy NGC 4414
Krajnović, D.; Emsellem, E.; McDermid, R. M. +7 more
We present our mass estimate of the central black hole in the isolated spiral galaxy NGC 4414. Using natural guide star adaptive optics assisted observations with the Gemini Near-Infrared Integral Field Spectrometer (NIFS) and the natural seeing Gemini Multi-Object Spectrographs-North (GMOS), we derived two-dimensional stellar kinematic maps of NG…
Quasar spectral variability from the XMM-Newton serendipitous source catalogue
Middei, R.; Vagnetti, F.; Serafinelli, R.
Context. X-ray spectral variability analyses of active galactic nuclei (AGN) with moderate luminosities and redshifts typically show a "softer when brighter" behaviour. Such a trend has rarely been investigated for high-luminosity AGNs (Lbol ≳ 1044 erg/s), nor for a wider redshift range (e.g. 0 ≲ z ≲ 5).
Aims: We present…
Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1
Maccarone, T. J.; Graham, Alister W.; Combes, F. +12 more
Aims: ESO 243-49 HLX-1, otherwise known as HLX-1, is an intermediate mass black hole (IMBH) candidate located 8'' (3.7 Kpc) from the centre of the edge-on S0 galaxy ESO 243-49. How the black hole came to be associated with this galaxy, and the nature of the environment in which it resides, remain unclear. Using multi-wavelength observations w…
ALMA high spatial resolution observations of the dense molecular region of NGC 6302
Sánchez Contreras, C.; Alcolea, J.; Corradi, R. L. M. +5 more
Context. The mechanism behind the shaping of bipolar planetary nebulae is still poorly understood. It is becoming increasingly clear that the main agents must operate at their innermost regions, where a significant equatorial density enhancement should be present and related to the collimation of light and jet launching from the central star prefe…
Vertical magnetic field gradient in the photospheric layers of sunspots
Joshi, Jayant; Lagg, Andreas; Hirzberger, Johann +2 more
Aims: We investigate the vertical gradient of the magnetic field of sunspots in the photospheric layer.
Methods: Independent observations were obtained with the Solar Optical Telescope/Spectropolarimeter (SOT/SP) on board the Hinode spacecraft and with the Tenrife Infrared Polarimeter-2 (TIP-2) mounted at the German Vacuum Tower Telescop…
Inversion of the decay of the cyclotron line energy in Hercules X-1
Harrison, F.; Klochkov, D.; Wilms, J. +3 more
Recent observations of Her X-1 with NuSTAR and INTEGRAL in 2016 have provided evidence that the 20-year decay of the cyclotron line energy found between 1996 and 2015 has ended and that an inversion with a new increase, possibly similar to the one observed around 1990-1993, has started. We consider this a strong motivation for further observations…
The δ Scuti pulsations of β Pictoris as observed by ASTEP from Antarctica
Christille, J. -M.; Lagrange, A. -M.; Chapellier, E. +13 more
Aims: The Antarctica Search for Transiting Extrasolar Planets (ASTEP), an automatized 400 mm telescope located at Concordia station in Antarctica, monitored β Pictoris continuously to detect any variability linked to the transit of the Hill sphere of its planet β Pictoris b. The long observation sequence, from March to September 2017, combine…