Search Publications
Sh2-138: physical environment around a small cluster of massive stars
Bhatt, B. C.; Dewangan, L. K.; Ojha, D. K. +4 more
We present a multiwavelength study of the Sh2-138, a Galactic compact H II region. The data comprise of optical and near-infrared (NIR) photometric and spectroscopic observations from the 2-m Himalayan Chandra Telescope, radio observations from the Giant Metrewave Radio Telescope (GMRT), and archival data covering radio through NIR wavelengths. A …
5.9-keV Mn K-shell X-ray luminosity from the decay of 55Fe in Type Ia supernova models
Wilms, J.; Diehl, R.; Sim, S. A. +12 more
We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two three-dimensional explosion models: a near-Chandrasekhar mass delayed detonation and a …
A comparative study of four significance measures for periodicity detection in astronomical surveys
Holl, Berry; Rimoldini, Lorenzo; Mowlavi, Nami +8 more
We study the problem of periodicity detection in massive data sets of photometric or radial velocity time series, as presented by ESA's Gaia mission. Periodicity detection hinges on the estimation of the false alarm probability of the extremum of the periodogram of the time series. We consider the problem of its estimation with two main issues in …
Reconciling Planck cluster counts and cosmology? Chandra/XMM instrumental calibration and hydrostatic mass bias
Reiprich, Thomas H.; Massey, Richard; Israel, Holger +2 more
The mass of galaxy clusters can be inferred from the temperature of their X-ray-emitting gas, TX. Their masses may be underestimated if it is assumed that the gas is in hydrostatic equilibrium, by an amount bhyd ∼ (20 ± 10) per cent suggested by simulations. We have previously found consistency between a sample of observed Ch…
How elevated is the dynamical-to-stellar mass ratio of the ultracompact dwarf S999?
Janz, Joachim; Penny, Samantha J.; Forbes, Duncan A. +4 more
Here we present new Keck Echelle Spectrograph and Imager high-resolution spectroscopy and deep archival Hubble Space Telescope/Advanced Camera for Surveys imaging for S999, an ultracompact dwarf in the vicinity of M87, which was claimed to have an extremely high dynamical-to-stellar mass ratio. Our data increase the total integration times by a fa…
The benchmark black hole in NGC 4258: dynamical models from high-resolution two-dimensional stellar kinematics
Storchi-Bergmann, Thaisa; Riffel, Rogemar A.; Cappellari, Michele +2 more
NGC 4258 is the galaxy with the most accurate (maser-based) determination for the mass of the supermassive black hole (SMBH) in its nucleus. In this work, we present a two-dimensional mapping of the stellar kinematics in the inner 3.0 arcsec × 3.0 arcsec = 100 pc × 100 pc of NGC 4258 using adaptive-optics observations obtained with the Near-Infrar…
Analysis of Sunyaev-Zel'dovich effect mass-observable relations using South Pole Telescope observations of an X-ray selected sample of low-mass galaxy clusters and groups
Gladders, M. D.; Rest, A.; Foley, R. J. +63 more
We use microwave observations from the South Pole Telescope (SPT) to examine the Sunyaev-Zel'dovich effect (SZE) signatures of a sample of 46 X-ray selected groups and clusters drawn from ∼6 deg2 of the XMM-Newton Blanco Cosmology Survey. These systems extend to redshift z = 1.02 and probe the SZE signal to the lowest X-ray luminosities…
The SLUGGS survey: combining stellar and globular cluster metallicities in the outer regions of early-type galaxies
Spitler, Lee R.; Forbes, Duncan A.; Romanowsky, Aaron J. +9 more
The outer halo regions of early-type galaxies carry key information about their past accretion history. However, spectroscopically probing the stellar component at such galactocentric radii is still challenging. Using the DEep Imaging Multi-Object Spectrograph on the Keck, we have been able to measure the metallicities of the stellar and globular …
On the distances of planetary nebulae
Smith, Haywood
Past calibrations of statistical distance scales for planetary nebulae have been problematic, especially with regard to `short' versus `long' scales. Reconsidering the calibration process naturally involves examining the precision and especially the systematic errors of various distance methods. Here, we present a different calibration strategy, n…
The magnetic field and spectral variability of the He-weak star HR 2949
Stahl, O.; Rivinius, Th.; Wade, G. A. +6 more
We analyse a high-resolution spectropolarimetric data set collected for the He-weak B3p IV star HR 2949. The Zeeman effect is visible in the circularly polarized component of numerous spectral lines. The longitudinal magnetic field varies between approximately -650 and +150 G. The polar strength of the surface magnetic dipole is calculated to be 2…