Spectral energy distribution profiles from AGN accretion disc in multigap set-up

Štolc, Marcel; Czerny, B.; Karas, Vladimír

doi:10.1093/mnras/stad1127

Cited by 4 publications

(1 citation statement)

References 132 publications

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“…This can be interpreted to be predominantly the intrinsic color excess expected for the majority of type I QSOs (Richards et al 2003). This extinction originates in the circumnuclear medium, e.g., in an obscuring torus, a warped disk-like structure, or an outflowing clumpy wind within ∼1 pc from the supermassive black hole Gohil & Ballantyne 2017;Gaskell & Harrington 2018;Gaskell et al 2023), and the host galaxy interstellar medium, also see Stolc et al (2023) and Czerny et al (2023c) for discussions. Dust can also be present on the scales of a few thousand gravitational radii, i.e., on subparsec scales, within the BLR clouds (Pandey et al 2023).…”

Section: Relation To the Extinction Curve And E B − Vmentioning

confidence: 95%

Effect of Extinction on Quasar Luminosity Distances Determined from UV and X-Ray Flux Measurements

Zajaček,

Czerny,

Khadka

et al. 2024

ApJ

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In Khadka et al., a sample of X-ray-detected reverberation-mapped quasars was presented and applied for the comparison of cosmological constraints inferred using two well-established relations in active galactic nuclei—the X-ray/UV luminosity (L X –L UV) relation and the broad-line region radius–luminosity (R–L) relation. L X –L UV and R–L luminosity distances to the same quasars exhibit a distribution of their differences that is generally asymmetric and positively shifted for the six cosmological models we consider. We demonstrate that this behavior can be interpreted qualitatively as arising as a result of the dust extinction of UV/X-ray quasar emission. We show that the extinction always contributes to the nonzero difference between L X –L UV-based and R–L-based luminosity distances and we derive a linear relationship between the X-ray/UV color index E X−UV and the luminosity-distance difference, which also depends on the value of the L X –L UV relation slope. Taking into account the median and the peak values of the luminosity-distance difference distributions, the average X-ray/UV color index falls in the range of E ¯ X − UV = 0.03 – 0.28 mag for the current sample of 58 sources. This amount of extinction is typical for the majority of quasars and can be attributed to the circumnuclear and interstellar media of host galaxies. After applying the standard hard X-ray and far-UV extinction cuts, heavily extincted sources are removed but overall the shift toward positive values persists. The effect of extinction on luminosity distances is more pronounced for the L X –L UV relation since the extinction of UV and X-ray emissions both contribute.

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Section: Relation To the Extinction Curve And E B − Vmentioning

confidence: 95%

Effect of Extinction on Quasar Luminosity Distances Determined from UV and X-Ray Flux Measurements

Zajaček,

Czerny,

Khadka

et al. 2024

ApJ

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Science with a Small Two-Band UV-Photometry Mission III: Active Galactic Nuclei and Nuclear Transients

Zajaček,

Czerny,

Jaiswal

et al. 2024

Space Sci Rev

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In this review, the third one in the series focused on a small two-band UV-photometry mission, we assess possibilities for a small UV two-band photometry mission in studying accreting supermassive black holes (SMBHs; mass range $\sim 10^{6}$ ∼ 10 6 –$10^{10}\,M_{\odot }$ 10 10 M ⊙ ). We focus on the following observational concepts: (i) dedicated monitoring of selected type-I Active Galactic Nuclei (AGN) in order to measure the time delay between the far-UV, the near-UV, and other wavebands (X-ray and optical), (ii) nuclear transients including (partial) tidal disruption events and repetitive nuclear transients, and (iii) the study of peculiar sources, such as changing-look AGN, hollows and gaps in accretion disks, low-luminosity AGN, and candidates for Intermediate-Mass Black Holes (IMBHs; mass range $\sim 10^{2}$ ∼ 10 2 –$10^{5}\,M_{\odot }$ 10 5 M ⊙ ) in galactic nuclei. The importance of a small UV mission for the observing program (i) is to provide intense, high-cadence monitoring of selected sources, which will be beneficial for, e.g. reverberation-mapping of accretion disks and subsequently confronting accretion-disk models with observations. For program (ii), a relatively small UV space telescope is versatile enough to start monitoring a transient event within ≲ 20 minutes after receiving the trigger; such a moderately fast repointing capability will be highly beneficial. Peculiar sources within the program (iii) will be of interest to a wider community and will create an environment for competitive observing proposals. For tidal disruption events (TDEs), high-cadence UV monitoring is crucial for distinguishing among different scenarios for the origin of the UV emission. The small two-band UV space telescope will also provide information about the near- and far-UV continuum variability for rare transients, such as repetitive partial TDEs and jetted TDEs. We also discuss the possibilities to study and analyze sources with non-standard accretion flows, such as AGN with gappy disks, low-luminosity active galactic nuclei with intermittent accretion, and SMBH binaries potentially involving intermediate-mass black holes.

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Repeating nuclear transients as candidate electromagnetic counterparts of LISA extreme mass ratio inspirals

Kejriwal,

Witzany,

Zajaček

et al. 2024

Monthly Notices of the Royal Astronomical Society

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Extreme-mass-ratio inspirals (EMRIs) are one of the primary targets for the recently adopted millihertz gravitational-wave (GW) observatory LISA. Some previous studies have argued that a fraction of all EMRIs form in matter-rich environments, and can potentially explain the dozens of soft X-ray band ($\sim 10^{-1} \rm keV$), low-frequency (∼0.1 mHz) periodic phenomena known as quasi-periodic eruptions (QPEs) and quasi-periodic oscillations (QPOs). Here, using a representative EMRI population retrofitted with cutoffs on LISA-band SNRs and luminosity distances to account for the sensitivity of current instruments, we estimate the mean frequency band in which QPEs and QPOs originating from detectable LISA EMRIs may be emitting an X-ray signal “today” (i.e., in 2024) to be 0.46 ± 0.22 mHz. We also model the well-known QPO source, RE J1034+396, which falls in this frequency band, as an EMRI assuming its primary black hole mass to be 106 − 107M⊙. Through a prior-predictive analysis, we estimate the orbiting compact object’s mass to be $46^{+ 10}_{-40} M_\odot$ and the source’s LISA-band SNR as ≈14, highlighting it as a candidate multi-messenger EMRI target. We also highlight the role of current and near-future X-ray and UV observatories in enabling multi-messenger observations of EMRIs in conjunction with LISA, and conclude with a discussion of caveats of the current analysis, such as the exclusion of eccentricity and inclination from the model, and the measurability of sub-solar mass compact object EMRIs.

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Spectral energy distribution profiles from AGN accretion disc in multigap set-up

Cited by 4 publications

References 132 publications

Effect of Extinction on Quasar Luminosity Distances Determined from UV and X-Ray Flux Measurements

Effect of Extinction on Quasar Luminosity Distances Determined from UV and X-Ray Flux Measurements

Science with a Small Two-Band UV-Photometry Mission III: Active Galactic Nuclei and Nuclear Transients

Repeating nuclear transients as candidate electromagnetic counterparts of LISA extreme mass ratio inspirals

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