The Spread of Metals into the Low-redshift Intergalactic Medium

Pratt, Cameron T.; Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.

doi:10.3847/1538-4357/aaaaac

Cited by 15 publications

(17 citation statements)

References 49 publications

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“…The limiting luminosities obtained around z ≤ 0.1 absorbers are not so faint as to suggest that virtually all galaxies have been surveyed. Galaxies with L ≥ 0.1 L * are thought to be the dominant source for metal-enriched gas expelled into the CGM and IGM (Prochaska et al 2011;Stocke et al 2013;Burchett et al 2015;Keeney et al 2017;Pratt et al 2018), so these survey limits are sufficient for many local universe investigations.…”

Section: Discussionmentioning

confidence: 99%

“…However, studies of the extent to which various metal ions extend away from galaxies (Chen et al 1998;Penton et al 2004;Stocke et al 2006Stocke et al , 2013Pratt et al 2018) show that the combination of line strength and absorber ionization parameter (see Stocke et al 2007) allows O VI absorption to trace metals more sensitively and so to much larger distances away from galaxies. The O VI doublet is also one of our very best ways to detect the "warm-hot" intergalactic medium (WHIM).…”

Section: Discussionmentioning

confidence: 99%

“…All of the closest galaxy-absorber associations have |∆v| < 400 km s −1 because we do not impose any lineof-sight corrections to the three-dimensional galaxy-absorber distance, D, until |∆v| exceeds this threshold. A more complete analysis of nearest-neighbor statistics for close galaxyabsorber separations, particularly as it relates to the spread of metals in the IGM, can be found in Pratt et al (2018).…”

Section: Galaxy-absorber Connectionsmentioning

confidence: 99%

“…We discuss these connections, whether they be the circulation of gas between the disk and CGM of an individual galaxy (Werk et al 2014;Tumlinson et al 2017) or the larger distribution of this gas in a cosmological context. To determine how far metals spread from individual galaxies (Stocke et al 2006;Pratt et al 2018), two datasets are required: UV absorption-line detections of the gas, and the distribution of galaxies around the regions probed by these UV detections.…”

Section: Introductionmentioning

confidence: 99%

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A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

Keeney

Stocke

Pratt

et al. 2018

ApJS

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To establish the connection between galaxies and UV-detected absorption systems in the local universe, a deep (g ≤ 20) and wide (∼ 20 radius) galaxy redshift survey is presented around 47 sight lines to UV-bright AGN observed by the Cosmic Origins Spectrograph (COS). Specific COS science team papers have used this survey to connect absorbers to galaxies, groups of galaxies, and large-scale structures, including voids. Here we present the technical details of the survey and the basic measurements required for its use, including redshifts for individual galaxies and uncertainties determined collectively by spectral class (emission-line, absorption-line, and composite spectra) and completeness for each sight line as a function of impact parameter and magnitude. For most of these sight lines the design criteria of > 90% completeness over a > 1 Mpc region down to 0.1 L * luminosities at z ≤ 0.1 allows a plausible association between low-z absorbers and individual galaxies. Lyα covering fractions are computed to approximate the star-forming and passive galaxy populations using the spectral classes above. In agreement with previous results, the covering fraction of star-forming galaxies with L ≥ 0.3 L * is consistent with unity inside one virial radius and declines slowly to > 50% at 4 virial radii. On the other hand, passive galaxies have lower covering fractions (∼ 60%) and a shallower decline with impact parameter, suggesting that their gaseous halos are patchy but have a larger scale-length than star-forming galaxies. All spectra obtained by this project are made available electronically for individual measurement and use.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Galaxy-absorber Connectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

Keeney

Stocke

Pratt

et al. 2018

ApJS

Self Cite

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“…There appears to be a consensus that, at least for z < 2, the predicted mean metallicity of the WHIM from simulations and O VI absorption studies is ∼ 0.1 Z (e.g. Wiersma, Schaye & Theuns 2011;S12;Danforth et al 2016;Pratt et al 2018).…”

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confidence: 99%

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

Dalton

Morris

Fumagalli

2021

Monthly Notices of the Royal Astronomical Society

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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.

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Probing the physical properties of the intergalactic medium using SRG/eROSITA spectra from blazars

Gatuzz,

Wilms,

Hämmerich

et al. 2024

A&A

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Most baryonic matter resides in the intergalactic medium (IGM). This diffuse gas is primarily composed of ionized hydrogen and helium and fills the space between galaxies. Observations of this environment are crucial for better understanding the physical processes in it. We present an analysis of the IGM absorption using blazar spectra from the first eROSITA all-sky survey (eRASS1) performed onboard of the Spectrum-Roentgen-Gamma mission (SRG) and XMM-Newton X-ray observations. First, we fit the continuum spectra using a log-parabolic spectrum model and fixed the Galactic absorption. Then, we included a collisional ionization equilibrium model, namely IONeq to account for the IGM absorption. The column density $N( H )$ and metallicity ($Z$) were set as free parameters. At the same time, the redshift of the absorber was fixed to half the blazar redshift as an approximation of the full line-of-sight absorber. We measured IGM-$N( H )$ for 147 sources for SRG and 10 sources for XMM-Newton . We found a clear trend between IGM-$N( H )$ and the blazar redshifts that scales as $(1+z)^ $. The mean hydrogen density at $z=0$ is $n_ $ cm$^ $. The mean temperature over the redshift range is $ 0.6$, and the mean metallicity is $Z=0.16 0.09$. We found no acceptable fit using a power-law model for the temperatures or metallicities as a function of the redshift. These results indicate that the IGM contributes substantially to the total absorption seen in the blazar spectra.

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The Spread of Metals into the Low-redshift Intergalactic Medium

Cited by 15 publications

References 49 publications

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

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

Probing the physical properties of the intergalactic medium using SRG/eROSITA spectra from blazars

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