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

Dalton, Tony; Morris, Simon L.

doi:10.1093/mnras/staa1321

Cited by 15 publications

(11 citation statements)

References 43 publications

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“…The easiest explanation involves material in the host galaxy, either local to the GRB (Galama & Wijers 2001;Stratta et al 2004;Gendre et al 2006;Schady et al 2007;Campana et al 2012) or on a more extended basis (HII regions, Watson et al 2013;molecular clouds, Reichart & Price 2002;Campana et al 2006). Another possibility involves the metal contribution from the intergalactic medium (IGM) along the line of site (Behar et al 2011;Starling et al 2013;Campana et al 2015;Dalton & Morris 2020). These possibilities are not mutually exclusive.…”

Section: Introductionmentioning

confidence: 99%

The variable absorption in the X-ray spectrum of GRB 190114C

Campana

Lazzati

Perna

et al. 2021

A&A

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Gamma-ray burst (GRB) 190114C was a bright burst that occurred in the local Universe (z = 0.425). It was the first GRB ever detected at teraelectronvolt (TeV) energies, and this was thanks to MAGIC. We characterize the ambient medium properties of the host galaxy through the study of the absorbing X-ray column density. Using a combination of Swift, XMM-Newton, and NuSTAR observations, we find that the GRB X-ray spectrum is characterized by a high column density that is well in excess of the expected Milky Way value and decreases, by a factor of ∼2, around ∼105 s. Such a variability is not common in GRBs. The most straightforward interpretation of the variability in terms of the photoionization of the ambient medium is not able to account for the decrease at such late times, when the source flux is less intense. Instead, we interpret the decrease as due to a clumped absorber, denser along the line of sight and surrounded by lower-density gas. After the detection at TeV energies of GRB 190114C, two other GRBs were promptly detected. These two also have high intrinsic column density values, and there are hints for a decrease in their column densities as well. We speculate that a high local column density might be a common ingredient of TeV-detected GRBs.

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Section: Introductionmentioning

confidence: 99%

The variable absorption in the X-ray spectrum of GRB 190114C

Campana

Lazzati

Perna

et al. 2021

A&A

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“…Schady et al 2011;Watson et al 2013;Buchner, Schulze & Bauer 2017). The other school of thought argues that while the host can have an absorption contribution, the IGM contributes substantially to the excess absorption and is redshift related (e.g Starling et al 2013a;Arcodia, Campana & Salvaterra 2016;Rahin & Behar 2019;Dalton & Morris 2020;Dalton, Morris & Fumagalli 2021, hereafter D20, D21). The convention in earlier studies using AGN and GRBs was to use solar metallicity for a neutral absorber, as a device used to place all of the absorbing column density measurements on a comparable scale.…”

Section: Introductionmentioning

confidence: 99%

Probing the physical properties of the intergalactic medium using blazars

Dalton

Morris

Fumagalli

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We use Swift blazar spectra to estimate the key intergalactic medium (IGM) properties of hydrogen column density (${N} {\rm \small {HXIGM}}$), metallicity and temperature over a redshift range of 0.03 ≤ z ≤ 4.7, using a collisional ionisation equilibrium (CIE) model for the ionised 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 ${N}{\rm \small {hxigm}}$ 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 ${N}{\rm \small {hxigm}}$ and variations in source flux or intrinsic power laws. Though some objects may have a bulk Comptonisation component which could mimic absorption, it did not alter our overall results. The ${N}{\rm \small {hxigm}}$ 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.

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“…Given the X-ray absorption might not reflect the true density in the GRB environment (e.g. Rahin & Behar 2019 ;Dalton & Morris 2020 ), it is possible that GRB 210419A resides in a highdensity surrounding medium that prevents low-frequency emission from escaping.…”

Section: S U M M a Ry A N D C O N C L U S I O N Smentioning

confidence: 99%

High time resolution search for prompt radio emission from the long GRB 210419A with the Murchison Widefield Array

Tian

Anderson

Hancock

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a low-frequency (170–200 MHz) search for prompt radio emission associated with the long GRB 210419A using the rapid-response mode of the Murchison Widefield Array (MWA), triggering observations with the Voltage Capture System (VCS) for the first time. The MWA began observing GRB 210419A within 89 s of its detection by Swift, enabling us to capture any dispersion delayed signal emitted by this GRB for a typical range of redshifts. We conducted a standard single pulse search with a temporal and spectral resolution of 100 μs and 10 kHz over a broad range of dispersion measures from 1 to 5000 pc cm−3, but none were detected. However, fluence upper limits of 77–224 Jy ms derived over a pulse width of 0.5–10 ms and a redshift of 0.6 < z < 4 are some of the most stringent at low radio frequencies. We compared these fluence limits to the GRB jet-interstellar medium (ISM) interaction model, placing constraints on the fraction of magnetic energy (εB ≲ [0.05–0.1]). We also searched for signals during the X-ray flaring activity of GRB 210419A on minute timescales in the image domain and found no emission, resulting in an intensity upper limit of 0.57 Jy beam−1, corresponding to a constraint of εB ≲ 10−3. Our non-detection could imply that GRB 210419A was at a high redshift, there was not enough magnetic energy for low-frequency emission, or that the radio waves did not escape from the GRB environment.

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

Cited by 15 publications

References 43 publications

The variable absorption in the X-ray spectrum of GRB 190114C

The variable absorption in the X-ray spectrum of GRB 190114C

Probing the physical properties of the intergalactic medium using blazars

High time resolution search for prompt radio emission from the long GRB 210419A with the Murchison Widefield Array

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