scholarly journals The structure of the ISM in the Zone of Avoidance by high-resolution multi-wavelength observations

2017 ◽  
Vol 12 (S333) ◽  
pp. 162-165
Author(s):  
L. V. Tóth ◽  
Y. Doi ◽  
S. Pinter ◽  
T. Kovács ◽  
S. Zahorecz ◽  
...  
Keyword(s):  
Column Density ◽  
Gamma Ray ◽  
High Spatial Resolution ◽  
Physical Parameters ◽  
Host Galaxies ◽  
Density Estimates ◽  
Sky Survey ◽  
Hydrogen Column Density ◽  
Multi Wavelength ◽  
Zone Of Avoidance

AbstractWe estimate the column density of the Galactic foreground interstellar medium (GFISM) in the direction of extragalactic sources. All-sky AKARI FIS infrared sky survey data might be used to trace the GFISM with a resolution of 2 arcminutes. The AKARI based GFISM hydrogen column density estimates are compared with similar quantities based on HI 21cm measurements of various resolution and of Planck results. High spatial resolution observations of the GFISM may be important recalculating the physical parameters of gamma-ray burst (GRB) host galaxies using the updated foreground parameters.

scholarly journals Exploring the pattern of the Galactic HI foreground of GRBs with the ATCA

2019 ◽  
Author(s):  
H Dénes ◽  
P A Jones ◽  
L V Tóth ◽  
S Zahorecz ◽  
B-C Koo ◽  
...  
Keyword(s):  
Column Density ◽  
Gamma Ray ◽  
Neutral Hydrogen ◽  
Far Infrared ◽  
Host Galaxy ◽  
Valuable Insight ◽  
Host Galaxies ◽  
Sky Survey ◽  
Hydrogen Column Density ◽  
Density Values

Abstract The afterglow of a gamma ray burst (GRB) can give us valuable insight into the properties of its host galaxy. To correctly interpret the spectra of the afterglow we need to have a good understanding of the foreground interstellar medium (ISM) in our own Galaxy. The common practice to correct for the foreground is to use neutral hydrogen (H i) data from the Leiden/Argentina/Bonn (LAB) survey. However, the poor spatial resolution of the single dish data may have a significant effect on the derived column densities. To investigate this, we present new high-resolution H i observations with the Australia Telescope Compact Array (ATCA) towards 4 GRBs. We combine the interferometric ATCA data with single dish data from the Galactic All Sky Survey (GASS) and derive new Galactic H i column densities towards the GRBs. We use these new foreground column densities to fit the Swift XRT X-ray spectra and calculate new intrinsic hydrogen column density values for the GRB host galaxies. We find that the new ATCA data shows higher Galactic H i column densities compared to the previous single dish data, which results in lower intrinsic column densities for the hosts. We investigate the line of sight optical depth near the GRBs and find that it may not be negligible towards one of the GRBs, which indicates that the intrinsic hydrogen column density of its host galaxy may be even lower. In addition, we compare our results to column densities derived from far-infrared data and find a reasonable agreement with the H i data.

scholarly journals The Zone of Avoidance as an X-ray absorber - the role of the galactic foreground modelling Swift XRT spectra

2017 ◽  
Vol 12 (S333) ◽  
pp. 170-171
Author(s):  
I. I. Racz ◽  
Z. Bagoly ◽  
L. V. Tóth ◽  
L. G. Balázs ◽  
I. Horvath ◽  
...  
Keyword(s):  
Column Density ◽  
Large Scale ◽  
Gamma Ray ◽  
Small Scale ◽  
Prompt Gamma ◽  
Gamma Emission ◽  
Essential Information ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Zone Of Avoidance

AbstractGamma-ray bursts (GRBs) are the most powerful explosive events in the Universe. The prompt gamma emission is followed by an X-ray afterglow that is also detected for over nine hundred GRBs by the Swift BAT and XRT detectors. The X-ray afterglow spectrum bears essential information about the burst, and the surrounding interstellar medium (ISM). Since the radiation travels through the line of sight intergalactic medium and the ISM in the Milky Way, the observed emission is influenced by extragalactic and galactic components. The column density of the Galactic foreground ranges several orders of magnitudes, due to both the large scale distribution of ISM and its small scale structures. We examined the effect of local HI column density on the penetrating X-ray emission, as the first step towards a precise modeling of the measured X-ray spectra. We fitted the X-ray spectra using the Xspec software, and checked how the shape of the initially power low spectrum changes with varying input Galactic HI column density. The total absorbing HI column is a sum of the intrinsic and Galactic component. We also investigated the model results for the intrinsic component varying the Galactic foreground. We found that such variations may alter the intrinsic hydrogen column density up to twenty-five percent. We will briefly discuss its consequences.

Probing the circumstellar medium of GRB afterglows through absorption-line observations

2007 ◽  
Vol 365 (1854) ◽  
pp. 1247-1253 ◽  
Author(s):  
Hsiao-Wen Chen
Keyword(s):  
Absorption Line ◽  
Radiation Field ◽  
High Velocity ◽  
Column Density ◽  
Gamma Ray ◽  
Neutral Hydrogen ◽  
Gamma Ray Bursts ◽  
Host Galaxies ◽  
Hydrogen Column Density ◽  
Progenitor Stars

A systematic search of Wolf–Rayet wind signatures, as represented by blue-shifted, high-velocity (|Δ v |=1000–5000 km s −1 ) C IV λλ 1548, 1550 absorption doublet has yielded an estimate of 20% for the incidence of these C IV absorbers near the host galaxies of gamma-ray bursts (GRBs). This is consistent with what is observed near classical damped Ly α absorbers that have a comparable neutral hydrogen column density as the GRB host galaxies. A detailed ionization analysis of these absorbers, including the associated low-ionization species, shows that the majority in fact originate in foreground galaxies along the sightline, rather than in the vicinity of the GRB afterglows. Taking into account the enhanced afterglow radiation field, the lack of Wolf–Rayet signatures can be applied to constrain the C/He ratio and the density contrast of the winds in the vicinity of GRB progenitor stars.

scholarly journals Statistical Properties of Gamma-Ray Burst Host Galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 190-190
Author(s):  
J. M. Chen ◽  
L. W. Jia ◽  
E. W. Liang
Keyword(s):  
Gamma Ray ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Statistical Properties ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Gamma Ray Burst ◽  
Star Forming ◽  
Hydrogen Column Density ◽  
Linear Fit

AbstractGRBs are the most luminous events in the Universe. They are detectable from local to high-z universe and may serve as probes for high-z galaxies (e.g., Savaglio et al. 2009; Kewley & Dopita 2002). We compile the observations for 61 GRB host galaxies from literature. Their redshifts range from 0.0085 to 6.295. We present the statistical properties of the GRB host galaxies, including the stellar mass (M*), star-forming rate (SFR), metallicity (Z), extinction (AV), and neutral hydrogen column density (NH). We explore possible correlations among the properties of gamma-ray burst host galaxies and their cosmic evolution with observations of 61 GRB host galaxies. Our results are shown in Figure 1. A clear Z-M* relation is found in our sample, which is Z ~ M0.4. The host galaxies of local GRBs with detection of accompanied supernovae also share the same relation with high-z GRB host galaxies. A trend that a more massive host galaxy tends to have a higher star-formation rate is found. The best linear fit gives a tentative relation, i.e, SFR ~ M0.75. No any correlation is found between AV and NH. A GRB host galaxy at a higher redshift also tends to have a higher SFR. Even in the same redshift, the SFR may vary over three orders of magnitude. The metallicity of the GRB host galaxies is statistically higher than that of the QSO DLAs. The full version of our results please refer to Chen et al. (2012).

scholarly journals A Possible Detection of CO (J = 3–2) Emission From the Host Galaxy of GRB 980425 with Atacama Submillimeter Telescope Experiment

2006 ◽  
Vol 2 (S235) ◽  
pp. 312-312
Author(s):  
Bunyo Hatsukade ◽  
Kotaro Kohno ◽  
Akira Endo ◽  
Tomoka Tosaki ◽  
Kouji Ohta ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Line Emission ◽  
Emission Feature ◽  
Star Formation History ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Long Duration ◽  
The Galaxy ◽  
Multi Wavelength

AbstractLong-duration gamma-ray bursts (GRBs) are considered to be due to the death of massive stars. Therefore, GRBs are closely associated with the star formation of host galaxies. Since GRBs can be detected at cosmological distances, they are expected to be probes of the star formation history of the Universe. In order to determine the use of GRBs, it is essential to understand the star formation of their hosts. Multi-wavelength observations have shown that the star formation rates (SFRs) of GRB hosts derived from submillimeter/radio observations are generally higher than those from optical/UV observations (Berger et al. 2003). This implies that GRB hosts have a large amount of molecular gas and massive star formation obscured by dust. In order to solve this problem, it is necessary to derive the SFRs in a method which is independent of existing methods and not affected by dust extinction.We observed 12CO (J = 3–2) line emission from the host galaxy of GRB 980425 using the Atacama Submillimeter Telescope Experiment (ASTE). Five points were observed covering the entire region of the galaxy, and we find possible emission features (S/N ~ 3 σ) at the velocity range corresponding to the redshift of the galaxy. By combining all spectra of five points, we obtain a global spectrum with a ~4 σ emission feature. If the features are real, this is the first detection of CO among GRB hosts. We derive the total gas mass of M(H2)=7 ± 2× 108M⊙ assuming a CO-to-H2 conversion factor of αCO = 8.0M⊙ (K km s−1 pc2)−1, which is deduced using the correlation between the αCO and the metallicity. The dynamical mass is calculated to be Mdyn=2× 1010M⊙, and M(H2)/Mdyn~3% is consistent with those of nearby dwarfs and normal spirals. The derived SFR is 0.5 ± 0.1 M⊙ yr−1 based on the Schmidt law. This SFR agrees with the results of previous Hα observations, suggesting that there is no significant obscured star formation in this host galaxy. This result implies that there is a variety of GRB hosts in terms of the presence of obscured star formation.

scholarly journals A quasar hiding behind two dusty absorbers

2018 ◽  
Vol 615 ◽  
pp. A43 ◽  
Author(s):  
K. E. Heintz ◽  
J. P. U. Fynbo ◽  
C. Ledoux ◽  
P. Jakobsson ◽  
P. Møller ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Column Density ◽  
Gamma Ray ◽  
Empirical Relation ◽  
Sloan Digital Sky Survey ◽  
Chemical Enrichment ◽  
Sky Survey ◽  
High Metal ◽  
Color Excess ◽  
Selection Of

The cosmic chemical enrichment as measured from damped Lyα absorbers (DLAs) will be underestimated if dusty and metal-rich absorbers have evaded identification. Here we report the discovery and present the spectroscopic observations of a quasar, KV-RQ 1500–0031, at z = 2.520 reddened by a likely dusty DLA at z = 2.428 and a strong Mg II absorber at z = 1.603. This quasar was identified as part of the KiDS-VIKING Red Quasar (KV-RQ) survey, specifically aimed at targeting dusty absorbers which may cause the background quasars to escape the optical selection of e.g. the Sloan Digital Sky Survey (SDSS) quasar sample. For the DLA we find an H I column density of logN(H I) = 21.2 ± 0.1 and a metallicity of [X/H] = − 0.90 ± 0.20 derived from an empirical relation based on the equivalent width of Si IIλ 1526. We observe a total visual extinction of AV = 0.16 mag induced by both absorbers. To put this case into context we compile a sample of 17 additional dusty (AV > 0.1 mag) DLAs toward quasars (QSO-DLAs) from the literature for which we characterize the overall properties, specifically in terms of H I column density, metallicity and dust properties. From this sample we also estimate a correction factor to the overall DLA metallicity budget as a function of the fractional contribution of dusty QSO-DLAs to the bulk of the known QSO-DLA population. We demonstrate that the dusty QSO-DLAs have high metal column densities (logN(H I) + [X/H]) and are more similar to gamma-ray burst (GRB)-selected DLAs (GRB-DLAs) than regular QSO-DLAs. We evaluate the effect of dust reddening in DLAs as well as illustrate how the induced color excess of the underlying quasars can be significant (up to ~1 mag in various optical bands), even for low to moderate extinction values (AV ≲ 0.6 mag). Finally we discuss the direct and indirect implications of a significant dust bias in both QSO- and GRB-DLA samples.

scholarly journals The X-shooter GRB afterglow legacy sample (XS-GRB)

2019 ◽  
Vol 623 ◽  
pp. A92 ◽  
Author(s):  
J. Selsing ◽  
D. Malesani ◽  
P. Goldoni ◽  
J. P. U. Fynbo ◽  
T. Krühler ◽  
...  
Keyword(s):  
Selection Criteria ◽  
Column Density ◽  
Neutral Hydrogen ◽  
Cosmic Time ◽  
Late Time ◽  
Host Galaxies ◽  
X Ray ◽  
Hydrogen Column Density ◽  
X Ray Absorption

In this work we present spectra of all γ-ray burst (GRB) afterglows that have been promptly observed with the X-shooter spectrograph until 31/03/2017. In total, we have obtained spectroscopic observations of 103 individual GRBs observed within 48 hours of the GRB trigger. Redshifts have been measured for 97 per cent of these, covering a redshift range from 0.059 to 7.84. Based on a set of observational selection criteria that minimise biases with regards to intrinsic properties of the GRBs, the follow-up effort has been focused on producing a homogeneously selected sample of 93 afterglow spectra for GRBs discovered by the Swift satellite. We here provide a public release of all the reduced spectra, including continuum estimates and telluric absorption corrections. For completeness, we also provide reductions for the 18 late-time observations of the underlying host galaxies. We provide an assessment of the degree of completeness with respect to the parent GRB population, in terms of the X-ray properties of the bursts in the sample and find that the sample presented here is representative of the full Swift sample. We have constrained the fraction of dark bursts to be <28 per cent and confirm previous results that higher optical darkness is correlated with increased X-ray absorption. For the 42 bursts for which it is possible, we have provided a measurement of the neutral hydrogen column density, increasing the total number of published HI column density measurements by ∼33 per cent. This dataset provides a unique resource to study the ISM across cosmic time, from the local progenitor surroundings to the intervening Universe.

scholarly journals Environmental Effects on Properties of Type 2 QSOs

2009 ◽  
Vol 5 (S267) ◽  
pp. 106-106
Author(s):  
Lin-wen Chen ◽  
Li-Ting Hsu
Keyword(s):  
Column Density ◽  
Neutral Hydrogen ◽  
Photometric Redshifts ◽  
X Ray ◽  
Sky Survey ◽  
Hydrogen Column Density ◽  
Population Figure ◽  
Two Populations ◽  
Projected Distance

Type 2 QSOs (QSO2s) are intrinsically luminous QSOs embedded in dusty environments. In this work, we study the radio, optical, and soft X-ray properties of 887 optically selected [O III]-based QSO2s (Reyes et al. 2008) at z<0.83 to investigate the connection between QSO2s and their environments. We use SDSS data to measure the luminosity-limited galaxy counts in a volume centered on each QSO2 and defined by Δ z<0.1 (based on photometric redshifts) and within a projected distance of 1.5 Mpc of the QSO2 (δ1.5Mpc). We used ROSAT All Sky Survey (RASS) data to estimate the X-ray excess. Hsu & Chen (2010), after correcting for Galactic absorption, obtain a lower limit for the intrinsic neutral hydrogen column density (NH) toward each of the QSO2s. About 50% of these sources have NH > 1022 cm−2. We take this value as a threshold to subdivide QSO2s into high- and low-NH groups, and compare their environments. The distributions δ1.5Mpc of the two populations show that, in regions of higher galaxy density, QSO2s are dominated by the high-NH population (Figure 1), suggesting a closer connection between more obscured QSO2s and surrounding galaxies.

scholarly journals Probing the physical properties of the intergalactic medium using gamma-ray bursts

2021 ◽  
Author(s):  
Tony Dalton ◽  
Simon L Morris ◽  
Michele Fumagalli
Keyword(s):  
Column Density ◽  
Intergalactic Medium ◽  
Gamma Ray ◽  
Uv Spectra ◽  
Rapid Decline ◽  
X Rays ◽  
Continuum Absorption ◽  
Hydrogen Column Density ◽  
Temperature Ranges ◽  
Parameter Ranges

Abstract We use Gamma-ray burst (GRB) spectra total continuum absorption to estimate the key intergalactic medium (IGM) properties of hydrogen column density ($\mathit {N}_{\mathrm{HXIGM}}$), metallicity, temperature and ionisation parameter over a redshift range of 1.6 ≤ z ≤ 6.3, using photo-ionisation (PIE) and collisional ionisation equilibrium (CIE) models for the ionised plasma. We use more realistic host metallicity, dust corrected where available, in generating the host absorption model, assuming that the host intrinsic hydrogen column density is equal to the measured ionisation corrected intrinsic neutral column from UV spectra (${\it N}_{\mathrm{H}\, \rm \small {I,IC}}$). We find that the IGM property results are similar, regardless of whether the model assumes all PIE or CIE. The $\mathit {N}_{\mathrm{HXIGM}}$ scales as (1 + z)1.0 − 1.9, with equivalent hydrogen mean density at z = 0 of $n_0 = 1.8^{+1.5}_{-1.2} \times 10^{-7}$ cm−3. The metallicity ranges from ∼0.1 Z⊙ at z ∼ 2 to ∼0.001 Z⊙ at redshift z &gt; 4. The PIE model implies a less rapid decline in average metallicity with redshift compared to CIE. Under CIE, the temperature ranges between 5.0 &lt; log (T/K) &lt; 7.1. For PIE the ionisation parameter ranges between 0.1 &lt; log (ξ) &lt; 2.9. Using our model, we conclude that the IGM contributes substantially to the total absorption seen in GRB spectra and that this contribution rises with redshift, explaining why the hydrogen column density inferred from X-rays is substantially in excess of the intrinsic host contribution measured in UV.

scholarly journals Multi-wavelength campaign on NGC 7469

2020 ◽  
Vol 633 ◽  
pp. A61 ◽  
Author(s):  
N. Arav ◽  
X. Xu ◽  
G. A. Kriss ◽  
C. Chamberlain ◽  
T. Miller ◽  
...  
Keyword(s):  
Simple Model ◽  
Column Density ◽  
Uv Spectra ◽  
Host Galaxies ◽  
Central Source ◽  
Upper Limit ◽  
Multi Wavelength ◽  
Solar Metallicity ◽  
Ngc 7469 ◽  
Total Column

Context. AGN outflows are thought to influence the evolution of their host galaxies and their super massive black holes. To better understand these outflows, we executed a deep multiwavelength campaign on NGC 7469. The resulting data, combined with those of earlier epochs, allowed us to construct a comprehensive physical, spatial, and temporal picture for this AGN wind. Aims. Our aim is to determine the distance of the UV outflow components from the central source, their abundances and total column-density, and the mechanism responsible for their observed absorption variability. Methods. We studied the UV spectra acquired during the campaign as well as from three previous epochs (2002–2010). Our main analysis tools are ionic column-density extraction techniques and photoionization models (both equilibrium and time-dependent models) based on the code CLOUDY. Results. For component 1 (at –600 km s−1) our findings include the following: metallicity that is roughly twice solar; a simple model based on a fixed total column-density absorber, reacting to changes in ionizing illumination that matches the different ionic column densities derived from four spectroscopic epochs spanning 13 years; and a distance of R = 6+2.5−1.5 pc from the central source. Component 2 (at –1430 km s−1) has shallow troughs and is at a much larger R. For component 3 (at –1880 km s−1) our findings include: a similar metallicity to component 1; a photoionization-based model can explain the major features of its complicated absorption trough variability and an upper limit of 60 or 150 pc on R. This upper limit is consistent and complementary to the X-ray derived lower limit of 12 or 31 pc for R. The total column density of the UV phase is roughly 1% and 0.1% of the lower and upper ionization components of the warm absorber, respectively. Conclusions. The NGC 7469 outflow shows super-solar metallicity similar to the outflow in Mrk 279, carbon and nitrogen are twice and four times more abundant than their solar values, respectively. Similar to the NGC 5548 case, a simple model can explain the physical characteristics and the variability observed in the outflow.

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