J/A+A/695/A15 Physical and emission properties of filament sample (Zhao+, 2025)
The warm-hot intergalactic medium in inter-cluster filaments.
A forecast for HUBS observations based on eRASS1 superclusters.
Zhao Y., Xu H., Liu A., Zhang X., Ji L., Chang J., Hu D., Werner N.,
Zhang Z., Cui W., Wu X.
<Astron. Astrophys. 695, A15 (2025)>
=2025A&A...695A..15Z 2025A&A...695A..15Z (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; X-ray sources ; Morphology
Keywords: instrumentation: detectors - techniques: imaging spectroscopy -
intergalactic medium - large-scale structure of Universe
Abstract:
Cosmological simulations indicate that nearly half of the baryons in
the nearby Universe are in the warm-hot intergalactic medium (WHIM)
phase, with about half of which residing in cosmic filaments
connecting galaxy clusters. Recent observational studies using stacked
survey data and deep exposures of galaxy cluster outskirts have
detected soft X-ray excess associated with optically identified
filaments. However, the physical characteristics of WHIM in filaments
remain largely undetermined due to the lack of direct spectral
diagnostics of individual targets, limited by the spectral resolution
of current instruments in the soft X-ray band. We aim to select
appropriate targets for WHIM characterization through pointing
observations with the future HUBS mission, which is designed with eV
level energy resolution in the 0.1-2.0keV band and a 1 square degree
field-of-view, complementing other planned microcalorimetry missions
such as Athena.We built a sample of 1577 inter-cluster filaments based
on the first eROSITA All-Sky Survey (eRASS1) supercluster catalog and
estimated their soft X-ray emission. Their modeled geometrical
properties and oxygen line intensities were used to select candidate
targets for HUBS observations.Four inter-cluster filaments were
selected as the most appropriated candidates. By simulating and
analyzing their mock observations, we demonstrated that with 200ks
HUBS exposure for each candidate, the gas properties of individual
filaments can be accurately determined, with the temperature
constrained to ±0.01keV, metallicity constrained to ≤±0.03 solar
and density constrained to <±10%. Elemental abundance of O, Ne, Mg,
and Fe can be measured separately, providing unprecedented insights
into the chemical history of the filament gas. We also showed that
direct mapping of the WHIM distribution is promising with narrow- band
imaging of the O VIII line.Our work forecasts that next-generation
X-ray missions such as HUBS will provide substantial improvement in
our understanding of the physical status and evolution history of the
diffuse WHIM gas in cosmic large-scale structure.
Description:
We provide physical and emission properties calculated using our
model, for the 1577 inter-cluster filaments selected from the eRASS1
supercluster catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 107 1577 Physical and emission properties of filament sample
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See also:
J/A+A/683/A130 : eRASS Western Galactic Hemisphere Superclusters (Liu+, 2024)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- GC1 Name of the first galaxy cluster connecting
to the filament (1eRASS JHHMMSS.s-DDMMSS)
25- 47 A23 --- GC2 Name of the second galaxy cluster connecting
to the filament (1eRASS JHHMMSS.s-DDMMSS)
49- 54 F6.4 --- z Average redshift of GC1 and GC2
56- 60 F5.2 10+20cm-2 nH Total hydrogen column density in the
direction of average coordinates between
the clusters
62- 65 F4.1 Mpc CoDist Comoving distance between the clusters
67- 70 F4.1 Mpc PhysDist Physical distance between the clusters
72- 76 F5.2 deg Sep Angular separation between the clusters
78- 83 F6.2 arcmin Width Width of the filament
85- 89 F5.2 arcmin CoreWidth Width of the filament core
91- 96 F6.2 arcmin Length Length of the filament
98-101 F4.1 deg IncAngle Angle of the filament w.r.t. line-of-sight
103-107 F5.2 --- SNR-O8 Signal-to-noise ratio of the OVIII line with
bandwidth of 6eV (1)
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Note (1): estimated for 200ks of HUBS exposure and 20arcmin2 extraction
region.
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Acknowledgements:
Yuanyuan Zhao, yuanyuan.zhao(at)sjtu.edu.cn
(End) Patricia Vannier [CDS] 31-Jan-2025