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 > 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 < log (T/K) < 7.1. For PIE the ionisation parameter ranges between 0.1 < log (ξ) < 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 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.

scholarly journals Probing the physical properties of the intergalactic medium using blazars

2021 ◽  
Vol 508 (2) ◽  
pp. 1701-1718
Author(s):  
Tony Dalton ◽  
Simon L Morris ◽  
Michele Fumagalli ◽  
Efrain Gatuzz
Keyword(s):  
Intergalactic Medium ◽  
Gamma Ray ◽  
Power Laws ◽  
Intrinsic Variability ◽  
Redshift Range ◽  
Exposure Data ◽  
Hydrogen Column Density ◽  
Source Data ◽  
The Mean ◽  
Collisional Ionization

ABSTRACT We use Swift blazar spectra to estimate the key intergalactic medium (IGM) properties of hydrogen column density ($\mathit {N}\small {\rm HXIGM}$), metallicity, and temperature over a redshift range of 0.03 ≤ z ≤ 4.7, using a collisional ionization equilibrium model for the ionized plasma. We adopted a conservative approach to the blazar continuum model given its intrinsic variability and use a range of power-law models. We subjected our results to a number of tests and found that the $\mathit {N}\small {\rm HXIGM}$ parameter was robust with respect to individual exposure data and co-added spectra for each source, and between Swift and XMM–Newton source data. We also found no relation between $\mathit {N}\small {\rm HXIGM}$ and variations in source flux or intrinsic power laws. Though some objects may have a bulk Comptonization component that could mimic absorption, it did not alter our overall results. The $\mathit {N}\small {\rm HXIGM}$ from the combined blazar sample scales as (1 + z)1.8 ± 0.2. The mean hydrogen density at z = 0 is n0 = (3.2 ± 0.5) × 10−7 cm−3. The mean IGM temperature over the full redshift range is log(T/K) =6.1 ± 0.1, and the mean metallicity is [X/H] = −1.62 ± 0.04(Z ∼ 0.02). When combining with the results with a gamma-ray burst (GRB) sample, we find the results are consistent over an extended redshift range of 0.03 ≤ z ≤ 6.3. Using our model for blazars and GRBs, we conclude that the IGM contributes substantially to the total absorption seen in both blazar and GRB spectra.

scholarly journals A rocket observation of cosmic X-rays in the energy range between 0.15 and 20 keV

1970 ◽  
Vol 37 ◽  
pp. 121-129
Author(s):  
S. Hayakawa ◽  
T. Kato ◽  
F. Makino ◽  
H. Ogawa ◽  
Y. Tanaka ◽  
...  
Keyword(s):  
Energy Range ◽  
Column Density ◽  
Galactic Plane ◽  
Galactic Latitude ◽  
X Rays ◽  
Diffuse Component ◽  
Absorption Effect ◽  
Interstellar Absorption ◽  
Hydrogen Column Density ◽  
Latitude Region

Cosmic X-rays were observed with three sets of proportional counters covering the energy range between 0.15 and 20 keV. The detector born on a spinning rocket scanned a celestial region in which the galactic latitude bII changed from 30° to −55° across the galactic plane in the Cygnus-Cassiopeia region. The spectrum of Cyg XR-2 thus obtained is represented by a thermal bremsstrahlung of temperature 3.4 keV modified by the interstellar absorption for the hydrogen column density of 3 × 1021 cm−2. The diffuse component showed an interstellar absorption effect, which was however found much weaker than one would expect if the diffuse component were due entirely to be of extragalactic origin. The spectrum obtained in the highest latitude region is represented approximately by a power law E−1.8 but shows a possible trough at about 1 keV.

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 Using realistic host galaxy metallicities to improve the GRB X-ray equivalent total hydrogen column density and constrain the intergalactic medium density

2020 ◽  
Vol 495 (2) ◽  
pp. 2342-2353
Author(s):  
Tony Dalton ◽  
Simon L Morris
Keyword(s):  
Column Density ◽  
Intergalactic Medium ◽  
Neutral Hydrogen ◽  
Accurate Estimate ◽  
Host Galaxy ◽  
Lower Envelope ◽  
Sample Mean ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Solar Metallicity

ABSTRACT It is known that the GRB equivalent hydrogen column density (NHX) changes with redshift and that, typically, NHX is greater than the GRB host neutral hydrogen column density. We have compiled a large sample of data for GRB NHX and metallicity [X/H]. The main aims of this paper are to generate improved NHX for our sample by using actual metallicities, dust corrected where available for detections, and for the remaining GRB, a more realistic average intrinsic metallicity using a standard adjustment from solar. Then, by approximating the GRB host intrinsic hydrogen column density using the measured neutral column (NHI, IC) adjusted for the ionization fraction, we isolate a more accurate estimate for the intergalactic medium (IGM) contribution. The GRB sample mean metallicity is = −1.17 ± 0.09 rms (or 0.07 ± 0.05 Z/Zsol) from a sample of 36 GRB with a redshift 1.76 ≤ z ≤ 5.91, substantially lower than the assumption of solar metallicity used as standard for many fitted NHX. Lower GRB host mean metallicity results in increased estimated NHX with the correction scaling with redshift as Δlog (NHX cm−2) = (0.59 ± 0.04)log(1 + z) + 0.18 ± 0.02. Of the 128 GRB with data for both NHX and NHI, IC in our sample, only six have NHI, IC > NHX when revised for realistic metallicity, compared to 32 when solar metallicity is assumed. The lower envelope of the revised NHX – NHI, IC, plotted against redshift can be fit by log(NHX – NHI, IC cm−2) = 20.3 + 2.4 log(1 + z). This is taken to be an estimate for the maximum IGM hydrogen column density as a function of redshift. Using this approach, we estimate an upper limit to the hydrogen density at redshift zero (n0) to be consistent with n0 = 0.17 × 10−7cm−3.

scholarly journals Determining a Relation between X-ray Luminosity and Orbital Period of X-ray Binaries

Eureka ◽  
2014 ◽  
Vol 4 (1) ◽  
pp. 13-18
Author(s):  
Tyler Naffin
Keyword(s):  
Orbital Period ◽  
Column Density ◽  
High Mass ◽  
X Rays ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Sky Monitor ◽  
The Relationship ◽  
X Ray Binaries

The goal of this project was to examine the relationship between the average x-ray luminosity and the orbital period of x-ray binaries.  Using the data gathered by the All-Sky Monitor instrument aboard the Rossi X-ray Timing Explorer, 29 sources were selected for investigation based on the intensity of the x-rays emitted from each of the sources.  A literature search was then performed to gather further details on each of the sources, including orbital period, distance, hydrogen column density, and classification of each source as either low- or high-mass x-ray binaries with either neutron star or black hole companions.  Sufficient data for 22 of the sources was known in order to create plots of the average luminosity versus the period, which allowed for the period-luminosity relationships for x-ray binaries to be further examined.

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.

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 Modelling the Soft X-Ray and EUV Emission in Classical Novae: EUVE and ROSAT Observations of V1974 Cygni

1996 ◽  
Vol 152 ◽  
pp. 401-405
Author(s):  
Guy S. Stringfellow ◽  
Stuart Bowyer
Keyword(s):  
Time Scales ◽  
White Dwarf ◽  
Column Density ◽  
Statistical Tests ◽  
X Rays ◽  
Rapid Variability ◽  
X Ray ◽  
Classical Novae ◽  
Hydrogen Column Density ◽  
Deep Survey

We have conducted an extensive analysis of the observability of Classical Novae with the EUVE Lex/B and Al/Ti/C detectors. Predicted count rates have been computed using optically thin, isothermal plasma models for solar and metal-rich compositions, and hot ONeMg white dwarf model atmospheres. We find EUVE to be quite sensitive to both the EUV and soft X-ray emission emitted by the underlying hot white dwarf during novae outbursts, except for the coolest temperatures with very high intervening hydrogen column density. These results are used to interpret the emission detected during the EUVE all-sky survey of Nova Cygni 1992 (≡ V1974 Cyg), 279–290 days after visual maximum. We find the best fit to the observed emission from V1974 Cyg arises from a hot ONeMg white dwarf with surface temperature ~ 4 × 105 K and a mass of ~1.2 M⊙, and derive an interstellar hydrogen column density of ~ 3 × 1021 cm−2. Virtually all this emission arises from supersoft X-rays rather than the EUV. We also report the detection of V1974 Cyg with the EUVE Deep Survey detector at 549 days after visual maximum. This observation is compatible with the above properties, indicating that the mechanism responsible for the soft X-ray emission, connected with the underlying white dwarf, had not yet entirely turned off. We also present analysis of a ROSAT PSPC observation which is contemporaneous with the EUVE survey observations; this independently confirms the high column density we derived from the EUVE survey observation. Light curves for the EUVE and ROSAT observations are presented. Statistical tests for variability show that all of these observations are indeed highly variable over various time scales. The EUVE survey data shows one day variations, the EUVE DS data show ~30 minute fluctuations, while the ROSAT data vary rapidly on time scales of seconds. The EUVE data shows no periodic variability on any time scale. The implications of the rapid variability are briefly discussed.

scholarly journals Introducing the HD+B model for pulsar wind nebulae: a hybrid hydrodynamics/radiative approach

2020 ◽  
Vol 494 (3) ◽  
pp. 4357-4370
Author(s):  
B Olmi ◽  
D F Torres
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Theoretical Modelling ◽  
X Rays ◽  
Pulsar Wind Nebulae ◽  
New Approach ◽  
Energy Gamma ◽  
Radiative Model ◽  
Pulsar Wind

ABSTRACT Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -by far- the most numerous expected population in the TeV regime, such characterization is important not only to learn about the sources per se from an individual and population perspective, but also to be able to connect them with observations at other frequencies, especially in radio and X-rays. Also, we need to remove the emission from nebulae in highly confused regions of the sky for revealing other underlying emitters. In this paper, we present a new approach for theoretical modelling of pulsar wind nebulae: a hybrid hydrodynamic-radiative model able to reproduce morphological features and spectra of the sources, with relatively limited numerical cost.

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