The eROSITA Final Equatorial-Depth Survey (eFEDS)

Liu, Teng; Buchner, Johannes; Nandra, K.; Merloni, A.; Dwelly, T.; Sanders, Jeremy; Salvato, M.; Arcodia, R.; Brusa, M.; Wolf, Julien; Georgakakis, A.; Böller, Thomas; Krumpe, M.; Lamer, G.; Waddell, Sophia G. H.; Urrutia, T.; Schwope, A. D.; Robrade, J.; Wilms, J.; Dauser, Thomas; Comparat, Johan; Toba, Yoshiki; Ichikawa, Kohei; Iwasawa, K.; Shen, Yue; Medel, Hector Ibarra

doi:10.1051/0004-6361/202141643

Cited by 57 publications

(33 citation statements)

References 49 publications

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“…The eROSITA and XRT backgrounds were first modelled empirically using the principal component analysis (PCA) technique described in Simmonds et al (2018) (see also Liu et al 2022a). The extracted source spectra, which contain a contribution from both the source and background emission, were then jointly fitted using the source and background models.…”

Section: Spectral Fittingmentioning

confidence: 99%

eRASSt J074426.3+291606: prompt accretion disc formation in a 'faint and slow' tidal disruption event

Malyali,

Liu,

Merloni

et al. 2023

Preprint

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We report on multi-wavelength observations of the tidal disruption event (TDE) candidate eRASSt J074426.3+291606 (J0744), located in the nucleus of a previously quiescent galaxy at 𝑧 = 0.0396. J0744 was first detected as a new, ultra-soft X-ray source (photon index ∼ 4) during the second SRG/eROSITA All-Sky Survey (eRASS2), where it had brightened in the 0.3-2 keV band by a factor of more than ∼160 relative to an archival 3𝜎 upper limit inferred from a serendipitous Chandra pointing in 2011. The transient was also independently found in the optical by the Zwicky Transient Factory (ZTF), with the eRASS2 detection occurring only ∼20 days after the peak optical brightness, suggesting that the accretion disc formed promptly in this TDE. Continued X-ray monitoring over the following ∼400 days by eROSITA, NICER XTI and Swift XRT showed a net decline by a factor of ∼100, albeit with large amplitude X-ray variability where the system fades, and then rebrightens, in the 0.3-2 keV band by a factor ∼50 during an 80 day period. Contemporaneous Swift UVOT observations during this extreme X-ray variability reveal a relatively smooth decline, which persists over ∼400 days post-optical peak. The peak observed optical luminosity (absolute 𝑔-band magnitude ∼ −16.8 mag) from this transient makes J0744 the faintest optically-detected TDE observed to date. However, contrasting the known set of 'faint and fast' TDEs, the optical emission from J0744 decays slowly (exponential decay timescale ∼120 days), making J0744 the first member of a potential new class of 'faint and slow' TDEs.

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Section: Spectral Fittingmentioning

confidence: 99%

eRASSt J074426.3+291606: prompt accretion disc formation in a 'faint and slow' tidal disruption event

Malyali,

Liu,

Merloni

et al. 2023

Preprint

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“…After the identification of the optical counterpart and the obtained redshift information, eROSITA team further analyzed their X-ray spectra properties. Liu et al (2022) compiled the X-ray fitting catalog for 21 952 sources with reliable counterparts and with good signal-to-noise ratios, and then performed the simple spectral X-ray fitting with XSPEC terminology of TBabs*zTBabs*powerlaw (Liu et al 2022), where the powerlaw (powerlaw) index (Γ) is set as free with the prior distribution centered at Γ = 2.0 with σ = 0.5, and log-uniform prior for the column density N H (zTBabs) with 4 × 10 19 < N H /cm −2 < 4 × 10 24 . The galactic absorption (TBabs) is also applied using the total N H,Gal measured by the neutral HI observations through the H4PI Collaboration (HI4PI Collaboration 2016) in the direction of the eFEDS field.…”

Section: Efeds X-ray Spectral Fitting Catalogmentioning

confidence: 99%

“…The galactic absorption (TBabs) is also applied using the total N H,Gal measured by the neutral HI observations through the H4PI Collaboration (HI4PI Collaboration 2016) in the direction of the eFEDS field. Utilizing the obtained redshift information by Salvato et al (2022), Liu et al (2022) derived key AGN properties, including the absorption corrected rest-frame 0.5−2.0 keV (L (abs,corr) 0.5−2 keV ) and the 2−10 keV X-ray luminosities (L (abs,corr) 2−10 keV ), the column density (N H ), and X-ray spectral index (Γ). In this study we limit the sample only to reliable spec-z and photo-z measurements (as discussed in Sect.…”

Section: Efeds X-ray Spectral Fitting Catalogmentioning

confidence: 99%

eROSITA Final Equatorial-Depth Survey (eFEDS)

Ichikawa

Yamashita

Merloni

et al. 2023

A&A

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We constructed the eROSITA X-ray catalog of radio galaxies discovered by the WERGS survey, made by cross-matching the wide area Subaru/Hyper Suprime-Cam (HSC) optical survey and VLA/FIRST 1.4 GHz radio survey. We report finding 393 eROSITA detected radio galaxies in the 0.5−2 keV band in the eFEDS field covering 140 deg2. Thanks to the wide and medium depth eFEDS X-ray survey down to f0.5 − 2 keV = 6.5 × 10−15 erg s−1 cm−2, the sample contains the rare and most X-ray luminous radio galaxies above the knee of the X-ray luminosity function, spanning 44 < log(L0.5−2 keV(abs,corr)/erg s−1) < 46.5 at 1 < z < 4. The sample also contains the sources around and below the knee for the sources 41 < log(L0.5−2 keV(abs,corr)/erg s−1) < 45 at z < 1. Based on the X-ray properties obtained by the spectral fitting, 37 sources show obscured active galactic nucleus (AGN) signatures with log(NH/cm−2) > 22. These obscured and radio AGN reside in 0.4 < z < 3.2, indicating that they are obscured counterparts of the radio-loud quasar, which were missed in the previous optical quasar surveys. By combining radio and X-ray luminosities, we also investigated the jet production efficiency ηjet = ηradPjet/LAGN,bol by utilizing the jet power of Pjet. We find that there are 14 sources with extremely high jet production efficiency at ηjet ≈ 1. This high ηjet value might be a result of the decreased radiation efficiency of ηrad < 0.1, due to the low accretion rate for those sources, and/or of the boosting due to the decline of LAGN,bol by a factor of 10−100 by keeping Pjet constant in the previous Myr, indicating the experience of the AGN feedback. Finally, inferring the BH masses from the stellar mass, we find that X-ray luminous sources show the excess of the radio emission with respect to the value estimated from the fundamental plane. This radio emission excess cannot be explained by the Doppler boosting alone, and therefore the disk–jet connection of X-ray luminous eFEDS-WERGS is fundamentally different from the conventional fundamental plane which mainly covers the low-accretion regime.

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“…This area encompasses 10294 extragalactic X-ray sources. Liu et al (2022) performed a systematic X-ray spectral fitting analysis on all the Xray systems, providing fluxes and luminosities -among other X-ray properties-for the eFEDS sources. We use their posterior median, intrinsic (absorption-corrected) X-ray fluxes in the 2 − 10 keV energy band.…”

Section: Efedsmentioning

confidence: 99%

Testing the evolutionary pathways of galaxies and their supermassive black holes and the impact of feedback from active galactic nuclei via large multiwavelength data sets

Mountrichas

Shankar

2022

Monthly Notices of the Royal Astronomical Society

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It is still a matter of intense debate how supermassive black holes (SMBH) grow, and the role played by feedback from active galactic nuclei (AGN) in the co-evolution of SMBHs and galaxies. To test the coevolution proposed by theoretical models, we compile a large AGN sample of 5639 X-ray detected AGN, over a wide redshift range, spanning nearly three orders of magnitude in X-ray luminosity. The AGN have been detected in the COSMOS-Legacy, the Boötes, the XMM-XXL and the eFEDS fields. Using the specific star formation rate estimates, we split the AGN host galaxies into star forming (SF), starburst (SB) and quiescent (Q). Our results show that the AGN accretion is increased in SB systems compared to SF and Q. Our analysis reveals a mild increase of LX with M*. The LX/SFR ratio has a weak dependence on M*, and at fixed M* it is highest in Q systems. The latter trend is mostly driven by the significant drop in SFR in the Q state. The measured strong variations in SFR from the SB/SF to Q mirror those predicted in merger models with AGN feedback. However, the observed mild variations in LX are at variance with the same models. We also study the evolution of SFR for a galaxy control sample and found that it is very similar to that of X-ray AGN. This suggests that either AGN play a minor role in the star formation quenching, or the relative timescales of the two processes are different.

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The eROSITA Final Equatorial-Depth Survey (eFEDS)

Cited by 57 publications

References 49 publications

eRASSt J074426.3+291606: prompt accretion disc formation in a 'faint and slow' tidal disruption event

eRASSt J074426.3+291606: prompt accretion disc formation in a 'faint and slow' tidal disruption event

eROSITA Final Equatorial-Depth Survey (eFEDS)

Testing the evolutionary pathways of galaxies and their supermassive black holes and the impact of feedback from active galactic nuclei via large multiwavelength data sets

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