ERRATUM: “THE OBSCURED FRACTION OF ACTIVE GALACTIC NUCLEI IN THE <i>XMM</i>-COSMOS SURVEY: A SPECTRAL ENERGY DISTRIBUTION PERSPECTIVE” (2013, ApJ, 777, 86)

Lusso, Elisabeta; Comastri, A.; Zamorani, G.; Richards, Gordon T.; Vignali, C.; Treister, Ezequiel; Schawinski, Kevin; Salvato, M.; Gilli, R.

doi:10.1088/0004-637x/784/2/176

Cited by 26 publications

(43 citation statements)

References 1 publication

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“…The fHeII evolution can also be modified by varying QSO SED index (α, fν ∝ ν −α Gaikwad et al 2019). However, we show in online supplementary appendix I3 that the observed thermal parameter evolution can not be matched by simply varying the QSO SED index within the observationally allowed range of α = 1.4 − 2.0 (Lusso et al 2014;Stevans et al 2014;Shull & Danforth 2020). For the HM12 UVB model both the QSO luminosity functions and QSO SED index need to be updated to be compatible with the most recent compilations of the relevant observation(see e.g.…”

Section: Appendix I: Thermal Parameter Evolution In Uvb Modelsmentioning

confidence: 74%

A consistent and robust measurement of the thermal state of the IGM at 2 ≤ z ≤ 4 from a large sample of Ly α forest spectra: evidence for late and rapid He ii reionization

Gaikwad

Srianand

Haehnelt

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We characterise the thermal state of the intergalactic medium (IGM) in ten redshift bins in the range 2 ≤ z ≤ 4 with a sample of 103 high resolution, high S/N Lyα forest spectra using four different flux distribution statistics. Our measurements are calibrated with mock spectra from a large suite of hydrodynamical simulations post-processed with our thermal IGM evolution code cite, finely sampling amplitude and slope of the expected temperature-density relation. The thermal parameters inferred from our measurements of the flux power spectrum, Doppler parameter distribution, as well as wavelet and curvature statistics agree well within their respective errors and all clearly show the peak in temperature and minimum in slope of the temperature density relation expected from He ii reionization. Combining our measurements from the different flux statistics gives T0 = (14750 ± 1322)K for the peak temperature at mean density and a corresponding minimum slope γ = 1.225 ± 0.120. The peak in the temperature evolution occurs around z ≈ 3, in agreement with previous measurements that had suggested the presence of such a peak, albeit with a large scatter. Using cite, we also calculate the thermal state of the IGM predicted by five widely used (spatially homogeneous) UV-background models. The rather rapid thermal evolution inferred by our measurements is well reproduced by two of the models, if we assume (physically well motivated) non-equilibrium evolution with photo-heating rates that are reduced by a moderate factor of ∼0.7 − 0.8. The other three models predict He ii reionization to be more extended with a higher temperature peak occurring somewhat earlier than our measurements suggest.

show abstract

Section: Appendix I: Thermal Parameter Evolution In Uvb Modelsmentioning

confidence: 74%

A consistent and robust measurement of the thermal state of the IGM at 2 ≤ z ≤ 4 from a large sample of Ly α forest spectra: evidence for late and rapid He ii reionization

Gaikwad

Srianand

Haehnelt

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The observed QSO spectral index (α, fν ∝ ν −α ) is another uncertain quantity in UVB calculations. The observations of stacked QSO spectra in the far ultra-violet suggests that QSO spectral indices vary from α = 1.4 to 2.0 (Lusso et al 2014;Stevans et al 2014;Shull & Danforth 2020). Recently Gaikwad et al (2019) showed that the effect of the QSO spectral index on thermal parameter evolution is degenerate with the redshift of He ii reionization in KS19 such that a flatter QSO SED corresponds to an earlier He ii reionization.…”

Section: Appendix H: Thermal Parameter Evolution In Uvb Modelsmentioning

confidence: 99%

A consistent and robust measurement of the thermal state of the IGM at $2 \leq z \leq 4$ from a large sample of Ly$α$ forest spectra: Evidence for late and rapid HeII reionization

Gaikwad,

Srianand,

Haehnelt

et al. 2020

Preprint

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We characterise the thermal state of the intergalactic medium (IGM) in ten redshift bins in the redshift range 2 ≤ z ≤ 4 with a sample of 103 high resolution, high S/N Lyα forest spectra using four different flux distribution statistics. Our measurements are calibrated with mock spectra from a large suite of hydrodynamical simulations post-processed with our thermal IGM evolution code cite, finely sampling amplitude and slope of the expected temperature-density relation. The thermal parameters inferred from our measurements of the flux power spectrum, Doppler parameter distribution, as well as wavelet and curvature statistics agree well within their respective errors and all clearly show the peak in temperature and minimum in slope of the temperature density relation expected from He ii reionization. Combining our measurements from the different flux statistics gives T 0 = (14750 ± 1322)K for the peak temperature at mean density and a corresponding minimum slope γ = 1.225 ± 0.120. The peak in the temperature evolution occurs at z ≈ 3, in agreement with previous measurements that had suggested the presence of such a peak, albeit with a large scatter. Using cite, we also calculate the thermal state of the IGM predicted by five widely used (spatially homogeneous) UV-background models. The rather rapid thermal evolution inferred by our measurements is well reproduced by two of the models, if we assume (physically well motivated) non-equilibrium evolution with photo-heating rates that are reduced by a moderate factor of ∼ 0.7 − 0.8. The other three models predict He ii reionization to be more extended with a somewhat earlier as well as higher temperature peak than our measurements suggest.

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“…Because we are interested in understanding the host galaxy properties, the bulk of the analysis concerns Type 2 AGNs, for which the nuclear light is optically obscured, therefore giving us access to spectral and photometric diagnostics of the host galaxy stellar content. A complete account of AGN including Type 1 is estimated by applying a correction factor for the Type 1/Type 2 ratio, which is observed to depend on AGN luminosity (e.g., Simpson 2005;Lusso et al 2013), and assuming that this ratio does not otherwise vary strongly as a function of SFR and M .…”

Section: Sample Selectionmentioning

confidence: 99%

“…However, we estimate their contribution to the total number (and fraction) of AGN based on the assumption that they share similar host galaxies as Type 2 AGNs, and that their contribution can be derived from the obscured (Type 2) fraction. Following the work by Lusso et al (2013), we adopt the functional form of a modified receding torus model proposed by Simpson 2005, which predicts the following relationship between the obscured fraction f obsc and AGN bolometric luminosity:…”

Section: Bolometric Correction Factormentioning

confidence: 99%

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The AGN-galaxy connection: Low-redshift benchmark & lessons learnt

Juneau

2019

Proc. IAU

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Several scenarios have been proposed to describe the physical connection between galaxies and their central active galactic nuclei (AGN). This connection could act on a range of spatial scales and vary across cosmic time. In these proceedings, we consider black hole and galaxy growth and whether that growth is affected by AGN feedback both based on statistical approaches – which reveal general population trends – and based on an individual case study – which gives us a more detailed insight on the physical processes at play. For the statistical approach, we showcase a low-redshift (0.04 < z < 0.2) SDSS sample with AGN classification based on a combination of emission-line diagnostic diagrams, and for which we account for sample selection by using a V/Vmax approach. The trends on the star formation rate - stellar mass (SFR – M*) plane suggest that the most likely connection is a common gas reservoir for star formation and AGN, and that they both decline as the gas reservoir is consumed. The trends established at low-redshift could act as a local benchmark against which to compare higher redshift studies. As a complementary approach, we use a detailed case study of a nearby AGN host with integral field spectroscopy from the VLT/MUSE instrument in order to spatially resolve the interplay between AGN feedback and the host galaxy. We find that the galaxy substructure likely plays a role by collimating and/or obscuring the outflows and radiation from the central engine. Ongoing and future work with 3D spectroscopy will enable us to learn more about galaxy and black hole coevolution. Lastly, we briefly discuss lessons learnt from both approaches.

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ERRATUM: “THE OBSCURED FRACTION OF ACTIVE GALACTIC NUCLEI IN THE XMM-COSMOS SURVEY: A SPECTRAL ENERGY DISTRIBUTION PERSPECTIVE” (2013, ApJ, 777, 86)

Cited by 26 publications

References 1 publication

A consistent and robust measurement of the thermal state of the IGM at 2 ≤ z ≤ 4 from a large sample of Ly α forest spectra: evidence for late and rapid He ii reionization

A consistent and robust measurement of the thermal state of the IGM at 2 ≤ z ≤ 4 from a large sample of Ly α forest spectra: evidence for late and rapid He ii reionization

A consistent and robust measurement of the thermal state of the IGM at $2 \leq z \leq 4$ from a large sample of Ly$α$ forest spectra: Evidence for late and rapid HeII reionization

The AGN-galaxy connection: Low-redshift benchmark & lessons learnt

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