Search results for " star formation"
showing 9 items of 9 documents
LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: exploring the origin of nuclear radio emission in active and inactive galaxies throug…
2021
Full list of authors: Baldi, R. D.; Williams, D. R. A.; Beswick, R. J.; McHardy, I.; Dullo, B. T.; Knapen, J. H.; Zanisi, L.; Argo, M. K.; Aalto, S.; Alberdi, A.; Baan, W. A.; Bendo, G. J.; Fenech, D. M.; Green, D. A.; Klöckner, H. -R.; Körding, E.; Maccarone, T. J.; Marcaide, J. M.; Mutie, I.; Panessa, F.; Pérez-Torres, M. A.; Romero-Cañizales, C.; Saikia, D. J.; Saikia, P.; Shankar, F.; Spencer, R. E.; Stevens, I. R.; Uttley, P.; Brinks, E.; Corbel, S.; Martí-Vidal, I.; Mundell, C. G.; Pahari, M.; Ward, M. J.
SHARDS: A global view of the star formation activity at z~0.84 and z~1.23
2015
et al.
Correlation between the spatial distribution of circumstellar disks and massive stars in the young open cluster NGC 6611
2009
Context: the observations of the proplyds in the Orion Nebula Cluster, showing clear evidence of ongoing photoevaporation, have provided a clear proof about the role of the externally induced photoevaporation in the evolution of circumstellar disks. NGC 6611 is an open cluster suitable to study disk photoevaporation, thanks to its large population of massive members and of stars with disk. In a previous work, we obtained evidence of the influence of the strong UV field generated by the massive cluster members on the evolution of disks around low-mass Pre-Main Sequence members. That work was based on a multi-band BVIJHK and X-ray catalog purposely compiled to select the cluster members with …
Multi-wavelength diagnostics of accretion in an X-ray selected sample of CTTSs
2010
High resolution X-ray spectroscopy has revealed soft X-rays from high density plasma in Classical T-Tauri stars (CTTSs), probably arising from the accretion shock region. However, the mass accretion rates derived from the X-ray observations are consistently lower than those derived from UV/optical/NIR studies. We aim to test the hypothesis that the high density soft X-ray emission is from accretion by analysing optical accretion tracers from an X-ray selected sample of CTTSs in a homogeneous manner. We analyse optical spectra of a sample of CTTSs and calculate the accretion rates based on measuring optical emission lines. These are then compared to the accretion rates derived from the X-ray…
Modeling accretion shocks on CTTSs and their X-ray emission
2009
Recent high spectral resolution X-ray observations of some CTTSs show the presence of high density plasma (ne=10^{11}-10^{13} cm^{-3}) at temperature T=2-3 MK. This plasma is likely heated up by an accretion shock on the star surface. We investigate this issue by an accurate modelling of the impact of an accretion stream onto the stellar chromosphere. Specifically, we present a large set of 1D hydrodynamical simulations aimed at investigating the physical properties of the system as a function of the density, and the velocity of the accretion stream and of the abundances of the heavy elements. We also synthesize the plasma X-ray emission from the simulations results, in order to link the ob…
Modeling the X-ray emission from jets observed with Chandra
2009
Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of LGRBs
2015
Aims: Long gamma-ray bursts (LGRBs) are associated with massive stars and are therefore linked to star formation. However, the conditions needed for the progenitor stars to produce LGRBs can affect the relation between the LGRB rate and star formation. By using the power of a complete LGRB sample, our long-term aim is to understand whether such a bias exists and, if it does, what its origin is. Methods: To reach our goal we use the Swift/BAT6 complete sample of LGRBs. In this first paper, we build the spectral energy distribution (SED) of the 14 z ⋆) from SED fitting. To investigate the presence of a bias in the LGRB-star formation relation we compare the stellar mass distribution of the LG…
Lyman break and ultraviolet-selected galaxies at z ~ 1 - II. PACS 100μm/160μm FIR detections
2013
In this work, we report the Photodetector Array Camera and Spectrometer (PACS) 100 μm/160 μm detections of a sample of 42 GALEX-selected and far-infrared (FIR)-detected Lyman break galaxies (LBGs) at z ~ 1 located in the Cosmic Evolution Survey (COSMOS) field and analyse their ultraviolet (UV) to FIR properties. The detection of these LBGs in the FIR indicates that they have a dust content high enough so that its emission can be directly detected. According to a spectral energy distribution (SED) fitting with stellar population templates to their UV-to-near-IR observed photometry, PACS-detected LBGs tend to be bigger (Reff ~ 4.1 kpc), more massive [log (M*/M⊙) ~ 10.7], dustier [Es(B - V) ~ …
Lyman break and ultraviolet-selected galaxies at z ̃ 1-I. Stellar populations from the ALHAMBRA survey
2013
We take advantage of the exceptional photometric coverage provided by the combination of GALEX data in the ultraviolet (UV) and the ALHAMBRA survey in the optical and near-infrared to analyse the physical properties of a sample of 1225 GALEX-selected Lyman break galaxies (LBGs) at 0.8 ≲ z ≲ 1.2 that are located in the COSMOS field. This is the largest sample of LBGs studied in this redshift range to date. According to a spectral energy distribution (SED) fitting with synthetic stellar population templates, we find that LBGs at z ̃ 1 are mostly young galaxies with a median age of 341 Myr and have intermediate dust attenuation, (Es(B - V)) ̃ 0.20. Owing to the selection criterion, LBGs at z ̃…