The cluster-scale environment of PKS 2155−304

Farina, Emanuele Paolo; Fumagalli, Michele; Decarli, Roberto; Fanidakis, N.

doi:10.1093/mnras/stv2277

Cited by 14 publications

(15 citation statements)

References 73 publications

(98 reference statements)

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“…5, we briefly discuss another gamma-ray source, PKS 2155−304, which sits [64] in a small unnamed group of galaxies. Recent observations [65] suggest that this group is considerably smaller than it was assumed earlier, which might imply lower and more regular magnetic fields and correspondingly weaker constraints on ALP parameters.…”

Section: Introductionmentioning

confidence: 69%

On the impact of magnetic-field models in galaxy clusters on constraints on axion-like particles from the lack of irregularities in high-energy spectra of astrophysical sources

Libanov

Troitsky

2020

Physics Letters B

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Photons may convert to axion-like particles (ALPs) in external magnetic fields. Under certain conditions, this effect should result in irregular features in observed spectra of astrophysical sources. Lack of such irregularities in particular spectra was used to constrain ALP parameters, with two most popular sources being the radio galaxy NGC 1275 and the blazar PKS 2155−304. The effect and, consequently, the constraints, depend on the magnetic fields through which the light from the source is propagated. Here, we revisit ALP constraints from gamma-ray observations of NGC 1275 taking into account the regular magnetic field of the X-ray cavity observed around this radio galaxy. This field was not accounted for in previous studies, which assumed a model of purely turbulent fields with coherence length much smaller than the cavity size. For the purely regular field, ALP constraints are relaxed considerably, compared to the purely turbulent one. Similar arguments hold also for PKS 2155−304. While the actual magnetic field around a source is an unknown sum of the turbulent and ordered components, the difference in results gives an estimate of the theoretical uncertainty of the study and calls for detailed measurements of magnetic fields around sources used to constrain ALP properties in this approach.

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Section: Introductionmentioning

confidence: 69%

On the impact of magnetic-field models in galaxy clusters on constraints on axion-like particles from the lack of irregularities in high-energy spectra of astrophysical sources

Libanov

Troitsky

2020

Physics Letters B

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“…Identification of the blazar's host group therefore represents a precise means of inferring its redshift (e.g. Rovero et al 2016;Farina et al 2016).…”

Section: Discovery and Redshift Of The Group Hosting 1es 1553+113mentioning

confidence: 99%

The Physical Origins of the Identified and Still Missing Components of the Warm–Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113

Johnson

Mulchaey

Chen

et al. 2019

ApJL

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The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of UV+X-ray spectra for surveys of the circum-/intergalactic medium (CGM/IGM). Nicastro et al. (2018) reported the detection of two O VII WHIM absorbers at z = 0.4339 and 0.3551 in its spectrum, suggesting that the WHIM is metal-rich and sufficient to close the missing baryons problem. Our survey indicates that the blazar is a member of a z = 0.433 group and that the higher-z O VII candidate arises from its intragroup medium. The resulting bias precludes its use in baryon censuses. The z = 0.3551 candidate occurs in an isolated environment 630 kpc from the nearest galaxy (with stellar mass log M * /M ≈ 9.7) which we show is unexpected for the WHIM. Finally, we characterize the galactic environments of broad H I Lyα absorbers (Doppler widths of b = 40 − 80 km s −1 ; T 4 × 10 5 K) which provide metallicity independent WHIM probes. On average, broad Lyα absorbers are ≈2× closer to the nearest luminous (L > 0.25L * ) galaxy (700 kpc) than narrow (b < 30 km s −1 ; T 4 × 10 5 K) ones (1300 kpc) but ≈2× further than O VI absorbers (350 kpc). These observations suggest that gravitational collapse heats portions of the IGM to form the WHIM but with feedback that does not enrich the IGM far beyond galaxy/group halos to levels currently observable in UV/X-ray metal lines.

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“…Although several works have undertaken the study of the immediate environment of BL Lacs (Farina et al 2016, and references therein), the use of the group/cluster redshift as a proxy for the blazar's redshift has been scarcely used (Pesce et al 1995;Muriel et al 2015;Rovero et al 2016) (see also Torres Zafra et al 2013, for preliminary results from the present project).…”

Section: Introductionmentioning

confidence: 99%

Redshift determination of the BL Lac object 3C 66A by the detection of its host galaxy cluster at z = 0.340 ★

Torres-Zafra

Cellone

Buzzoni

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The BL Lac object 3C 66A is one of the most luminous extragalactic sources at TeV γ-rays (VHE, i.e. E > 100 GeV). Since TeV γ-ray radiation is absorbed by the extragalactic background light (EBL), it is crucial to know the redshift of the source in order to reconstruct its original spectral energy distribution, as well as to constrain EBL models. However, the optical spectrum of this BL Lac is almost featureless, so a direct measurement of z is very difficult; in fact, the published redshift value for this source (z = 0.444) has been strongly questioned. Based on EBL absorption arguments, several constraints to its redshift, in the range 0.096 < z < 0.5, were proposed. Since these AGNs are hosted, typically, in early type galaxies that are members of groups or clusters, we have analysed spectro-photometrically the environment of 3C 66A, with the goal of finding the galaxy group hosting this blazar. This study was made using optical images of a 5.5 × 5.5 arcmin 2 field centred on the blazar, and spectra of 24 sources obtained with Gemini/GMOS-N multi-object spectroscopy. We found spectroscopic evidence of two galaxy groups along the blazar's line of sight: one at z 0.020 and a second one at z 0.340. The first one is consistent with a known foreground structure, while the second group here presented has six spectroscopically confirmed members. Their location along a red sequence in the colour-magnitude diagram allows us to identify 34 additional candidate members of the more distant group. The blazar's spectrum shows broad absorption features that we identify as arising in the intergalactic medium, thus allowing us to tentatively set a redshift lower limit at z 3C66A 0.33. As a consequence, we propose that 3C 66A is hosted in a galaxy that belongs to a cluster at z = 0.340.

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The cluster-scale environment of PKS 2155−304

Cited by 14 publications

References 73 publications

On the impact of magnetic-field models in galaxy clusters on constraints on axion-like particles from the lack of irregularities in high-energy spectra of astrophysical sources

On the impact of magnetic-field models in galaxy clusters on constraints on axion-like particles from the lack of irregularities in high-energy spectra of astrophysical sources

The Physical Origins of the Identified and Still Missing Components of the Warm–Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113

Redshift determination of the BL Lac object 3C 66A by the detection of its host galaxy cluster at z = 0.340 ★

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