scholarly journals On the origin of X-ray oxygen emission lines in obscured AGN

2020 ◽  
Vol 499 (4) ◽  
pp. 5107-5120
Author(s):  
V Reynaldi ◽  
M Guainazzi ◽  
S Bianchi ◽  
I Andruchow ◽  
F García ◽  
...  
Keyword(s):  
Far Infrared ◽  
Emission Lines ◽  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Model Predictions ◽  
Ionization Model ◽  
Collisional Ionization ◽  
Shed Light

ABSTRACT We present the Catalogue of High Resolution Spectra of Obscured Sources (CHRESOS) from the XMM–Newton Science Archive. It comprises the emission-line luminosities of H- and He-like transitions from C to Si, and the Fe 3C and Fe 3G L-shell ones. Here, we concentrate on the soft X-ray O vii (f) and O viii Lyα emission lines to shed light on to the physical processes with which their formation can be related to active galactic nucleus (AGN) versus star-forming regions. We compare their luminosity with that of two other important oxygen key lines [O iii] λ5007 Å, in the optical, and [O iv] 25.89 μm, in the infrared (IR). We also test O vii (f) and O viii Lyα luminosities against that of continuum bands in the IR and hard X-rays, which point to different ionization processes. We probe into those processes by analysing photoionization and collisional ionization model predictions upon our lines. We show that both scenarios can explain the formation and observed intensities of O vii (f) and O viii Lyα. By analysing the relationships between O vii (f) and O viii Lyα, and all other observables: [O iii] λ5007 Å, [O iv] 25.89 μm emission lines, and mid-infrared (MIR) 12 μm, far-infrared (FIR) 60 and 100 μm, 2–10 and 14–195 keV continuum bands, we conclude that the AGN radiation field is mainly responsible of the soft X-ray oxygen excitation.

scholarly journals The excitation mechanisms of X-ray oxygen emission-lines

2020 ◽  
Vol 15 (S359) ◽  
pp. 360-361
Author(s):  
Victoria Reynaldi ◽  
Matteo Guainazzi ◽  
Stefano Bianchi ◽  
Ileana Andruchow ◽  
Federico García ◽  
...  
Keyword(s):  
High Resolution ◽  
Active Galactic Nucleus ◽  
Emission Lines ◽  
X Rays ◽  
Physical Processes ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Excitation Mechanisms ◽  
Shed Light

AbstractWe present the Catalogue of High REsolution Spectra of Obscured Sources (CHRESOS) from the XMM-Newton Science Archive. It comprises soft X-ray emission-lines from C to Si and the Fe 3C and Fe 3G L-shell transitions. Here, we concentrate on the oxygen emission-lines O VII(f) and O VIII Lyα to shed light onto the physical processes with which their formation can be related to: active galactic nucleus vs. star-forming regions. We are analysing the relationships between the oxygen lines and the luminosities of: [OIII]λ5007, [OIV]25.89μm, MIR-12μm, FIR-60μm, FIR-100μm, and hard X-rays continuum bands.

scholarly journals X-Ray Valiabilities from Protostars in the RCrA Molecular Cloud

1998 ◽  
Vol 188 ◽  
pp. 234-235
Author(s):  
Kenji Hamaguchi ◽  
Hiroshi Murakami ◽  
Katsuji Koyama ◽  
Shiro Ueno
Keyword(s):  
Molecular Cloud ◽  
Mass Star ◽  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
The Core ◽  
Star Forming Regions

R CrA molecular cloud, at a distance of 130pc(Marraco, Rydgren 1981), is one of the active low-to-middle mass star forming regions. The core of this cloud, named Coronet, contains five protostar candidates. In 1994, we observed the Coronet Cluster using the X-ray satellite ASCA, and discovered hard X-rays from protostar candidates(Koyama et al. 1996).

scholarly journals The results of the search and study of young stellar objects with H emission in the Byurakan Observatory

2018 ◽  
Vol 2 (1) ◽  
pp. 80-90
Author(s):  
E. H. Nikoghosyan ◽  
Keyword(s):  
Statistical Analysis ◽  
Young Stars ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Optical Range ◽  
Stellar Objects ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions

One of the main observational properties of young stellar objects in the optical range is the presence of emission lines, in particular H (6563 Å). Therefore, detection of H emission is the most common spectroscopic means for identification of young stars. The paper presents the results of searching and studying of young stellar objects in several star forming regions carried out on the 2.6 m telescope in Byurakan observatory. The quantitative relationships between objects with different stage of activity are considered. In addition, a statistical analysis of H activity and other manifestations of PMS activity (X-ray, IR excess), as well as an evolutionary age of the H emitters in several star-forming regions is provided.

scholarly journals The VLT/MUSE view of the central galaxy in Abell 2052

2018 ◽  
Vol 612 ◽  
pp. A19 ◽  
Author(s):  
Barbara Balmaverde ◽  
Alessandro Capetti ◽  
Alessandro Marconi ◽  
Giacomo Venturi
Keyword(s):  
Interstellar Medium ◽  
Line Emission ◽  
Emission Lines ◽  
Expansion Velocity ◽  
Direct Estimate ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
The North ◽  
Integral Field Spectrograph

We report observations of the radio galaxy 3C 317 (at z = 0.0345) located at the center of the Abell cluster A2052, obtained with the VLT/MUSE integral field spectrograph. The Chandra images of this cluster show cavities in the X-ray emitting gas, which were produced by the expansion of the radio lobes inflated by the active galactic nucleus (AGN). Our exquisite MUSE data show with unprecedented detail the complex network of line emitting filaments enshrouding the northern X-ray cavity. We do not detect any emission lines from the southern cavity, with a luminosity asymmetry between the two regions higher than ~75. The emission lines produced by the warm phase of the interstellar medium (WIM) enable us to obtain unique information on the properties of the emitting gas. We find dense gas (up to 270 cm−3) that makes up part of a global quasi spherical outflow that is driven by the radio source, and obtain a direct estimate of the expansion velocity of the cavities (265 km s−1). The emission lines diagnostic rules out ionization from the AGN or from star-forming regions, suggesting instead ionization from slow shocks or from cosmic rays. The striking asymmetric line emission observed between the two cavities contrasts with the less pronounced differences between the north and south sides in the hot gas; this represents a significant new ingredient for our understanding of the process of the exchange of energy between the relativistic plasma and the external medium. We conclude that the expanding radio lobes displace the hot tenuous phase of the interstellar medium (ISM), but also impact the colder and denser ISM phases. These results show the effects of the AGN on its host and the importance of radio mode feedback.

Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

2020 ◽  
Vol 15 (S359) ◽  
pp. 17-21
Author(s):  
Karín Menéndez-Delmestre ◽  
Laurie Riguccini ◽  
Ezequiel Treister
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Far Infrared ◽  
Host Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Near Ir ◽  
X Ray Imaging ◽  
Combined Use ◽  
Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

scholarly journals Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

2020 ◽  
Vol 494 (2) ◽  
pp. 2823-2838 ◽  
Author(s):  
Ana Trčka ◽  
Maarten Baes ◽  
Peter Camps ◽  
Sharon E Meidt ◽  
James Trayford ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Physical Properties ◽  
Numerical Models ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Global Emission ◽  
Galaxy Sample ◽  
Galaxy Population

ABSTRACT We compare the spectral energy distributions (SEDs) and inferred physical properties for simulated and observed galaxies at low redshift. We exploit UV-submillimetre mock fluxes of ∼7000 z = 0 galaxies from the EAGLE suite of cosmological simulations, derived using the radiative transfer code skirt. We compare these to ∼800 observed galaxies in the UV-submillimetre range, from the DustPedia sample of nearby galaxies. To derive global properties, we apply the SED fitting code cigale consistently to both data sets, using the same set of ∼80 million models. The results of this comparison reveal overall agreement between the simulations and observations, both in the SEDs and in the derived physical properties, with a number of discrepancies. The optical and far-infrared regimes, and the scaling relations based upon the global emission, diffuse dust, and stellar mass, show high levels of agreement. However, the mid-infrared fluxes of the EAGLE galaxies are overestimated while the far-UV domain is not attenuated enough, compared to the observations. We attribute these discrepancies to a combination of galaxy population differences between the samples and limitations in the subgrid treatment of star-forming regions in the EAGLE-skirt post-processing recipe. Our findings show the importance of detailed radiative transfer calculations and consistent comparison, and provide suggestions for improved numerical models.

Radiation Production Using Femtosecond Electron Bunches

2005 ◽  
Vol 107 ◽  
pp. 11-14
Author(s):  
C. Thongbai ◽  
V. Jinamoon ◽  
N. Kangrang ◽  
K. Kusoljariyakul ◽  
S. Rimjaem ◽  
...  
Keyword(s):  
Far Infrared ◽  
Bunch Length ◽  
X Rays ◽  
Research Facility ◽  
X Ray ◽  
Electron Bunches ◽  
Rf Gun ◽  
Intense Radiation ◽  
Far Infrared Radiation ◽  
Femtosecond Electron Bunches

Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet, and a linear accelerator and can be used to produce femtosecond (fs) electromagnetic radiation pulses. At the Fast Neutron Research Facility (FNRF), Thailand, we are especially interested in production in Far-infrared (FIR) and x-radiation. In the far-infrared, radiation is emitted coherently for wavelengths which are longer than the electron bunch length, yielding intense radiation. Although, the x-rays emitted are incoherent, its femtosecond time scale is crucial for development of a femtosecond x-ray source.

Mid- to far-infrared mapping spectroscopy of galactic star-forming regions with ISO, spitzer, and AKARI

2008 ◽  
Vol 31 ◽  
pp. 191-192
Author(s):  
Y. Okada ◽  
T. Onaka ◽  
T. Miyata ◽  
Y.K. Okamoto ◽  
I. Sakon ◽  
...  
Keyword(s):  
Far Infrared ◽  
Star Forming ◽  
Star Forming Regions

Swift observations of gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1119-1128 ◽  
Author(s):  
Neil Gehrels
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Optical Observations ◽  
Nearby Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Other Information ◽  
Short Grbs

Since its launch on 20 November 2004, the Swift mission has been detecting approximately 100 gamma-ray bursts (GRBs) each year, and immediately (within approx. 90 s) starting simultaneous X-ray and UV/optical observations of the afterglow. It has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and a rapid follow-up by other observatories notified through the GCN. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations and the conclusion that short GRBs can occur in non-star-forming galaxies or regions, whereas long GRBs are strongly concentrated within the star-forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z ∼5–6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to a much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and the association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova.

scholarly journals Shocked Molecular Hydrogen from Star Forming Regions

1987 ◽  
Vol 115 ◽  
pp. 181-181 ◽  
Author(s):  
Adair P. Lane ◽  
John Bally
Keyword(s):  
Shock Waves ◽  
High Velocity ◽  
Molecular Hydrogen ◽  
Near Infrared ◽  
Young Stars ◽  
Emission Lines ◽  
Molecular Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Post Shock

Near infrared (2 micron) emission lines from molecular hydrogen provide a powerful probe of the morphology and energetics of outflows associated with stellar birth. The H2 emission regions trace the location of shock waves formed when the high velocity outflow from young stars encounters dense quiescent gas. Since H2 is the dominant coolant of the hot post-shock molecular gas, the H2 lines provide a measure of the fraction of the total mechanical luminosity radiated away from the cloud.

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