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Tidal disruption events around massive black holes confirm a universal accretion-state threshold at ~3% of Eddington, unifying them with X-ray binaries.

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2026-08-02 20:58 UTC pith:5Z6L6Z27

load-bearing objection Two well-observed high-mass TDEs with early hard X-rays, plus a suggestive but not yet established population-level state-transition claim; the bandpass selection effect is the main unresolved issue. the 4 major comments →

arxiv 2602.21624 v1 pith:5Z6L6Z27 submitted 2026-02-25 astro-ph.HE

AT2024lhc and AT2024kmq in the landscape of featureless tidal disruption events

Yuhan Yao , Ryan Chornock , Andrew Mummery , Raffaella Margutti , Marat Gilfanov , Muryel Guolo , Eric R. Coughlin , Wenbin Lu
show 34 more authors
Joheen Chakraborty Dheeraj R. Pasham Kate D. Alexander Olivia Aspegren Charlotte R. Angus Xinze Guo Xander J. Hall Erica Hammerstein K.-Ryan Hinds Anna Y. Q. Ho Xiaoshan Huang Elias Kammoun Natalie LeBaron Matteo Lucchini Zo\"e McGrath Matt Nicholl Daniel A. Perley R. Michael Rich Genevieve Schroeder Xinyue Sheng Jesper Sollerman Jean Somalwar Jacob R. Wise Michael W. Coughlin Andrew Drake Matthew J. Graham George Helou Joahan C. Jaimes Mansi M. Kasliwal Ashish A. Mahabal Pavel Medvedev Josiah Purdum Ben Rusholme Rashid Sunyaev
This is my paper
classification astro-ph.HE
keywords tidal disruption eventsX-ray binariesaccretion state transitionsblack hole accretionfeatureless spectracoronal X-ray emissionEddington ratiodisk theory
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper studies two newly discovered tidal disruption events (TDEs) — stars torn apart by supermassive black holes — hosted by black holes of roughly 10^8 solar masses. Both show luminous, rapidly varying hard X-ray emission that appears within weeks, which the authors attribute to a compact corona rather than a jet. By placing these events in a sample of thirty X-ray-observed TDEs, they find a clear mass segregation: low-mass black holes (10^6 solar masses) stay in a soft X-ray state for years, intermediate masses (10^7) transition from soft to hard around one year, and high masses (10^8) are hard from the start. The authors argue this pattern is exactly what simple accretion disk theory predicts if TDE disks undergo the same soft-to-hard state transition as stellar-mass X-ray binaries, at a critical Eddington-scaled accretion rate of about 0.03. If correct, this unifies TDE accretion physics with the well-studied state transitions in X-ray binaries and confirms a theoretical prediction about when TDE disks should turn hard.

Core claim

The paper's central claim is that the diverse X-ray spectral states observed in tidal disruption events can be understood as a single mass-dependent sequence driven by the decline of the Eddington-normalized accretion rate. Using two new high-mass TDEs plus a comparison sample of eROSITA-observed TDEs, the authors show that black hole mass segregates the X-ray behavior: low-mass black holes stay soft, intermediate masses transition, and high masses are hard from the outset. They interpret this as evidence that TDE disks undergo a soft-to-hard state transition at a critical accretion rate of Ṁ_acc ≈ 0.03 Ṁ_Edd, matching the value seen in X-ray binaries. The transition timescale predicted by s

What carries the argument

The central mechanism is the time-dependent evolution of a standard thin accretion disk fed by stellar debris, whose accretion rate declines as a power law in time. The key identity is the scaling of the time to reach a given Eddington ratio: t_tr ∝ M_BH^{-3/4}, derived from viscous disk theory. This scaling implies that for a fixed critical threshold (here ṁ = 0.03), higher-mass black holes cross the threshold much sooner after disruption, which naturally produces the observed mass segregation of X-ray spectral states. The paper also uses the concept of the critical Eddington-scaled accretion rate for the soft-to-hard transition, borrowed from X-ray binary phenomenology, to set the threshol

Load-bearing premise

The entire mass-segregation interpretation hinges on the assumption that the observed X-ray spectral states are driven by accretion-rate evolution rather than by a soft-X-ray detection bias — that a soft-state high-mass TDE would not have been detected in the eROSITA sample.

What would settle it

A direct test would be to find a TDE around a black hole of ~10^8 solar masses that shows a soft X-ray spectrum (Γ > 4) at early times (within a few months of optical peak), which would contradict the claim that high-mass TDEs are hard from the outset. Conversely, if a systematic X-ray survey with sensitivity down to the EUV/soft X-ray band reveals a population of soft-state high-mass TDEs, the visibility-bias interpretation would be favored over the universal-state-transition interpretation.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

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If this is right

  • If the ṁ ≈ 0.03 transition is universal, then the X-ray spectral state of a TDE at a given time encodes its black hole mass and accretion rate, enabling mass estimates from X-ray observations alone.
  • The mass segregation implies that soft X-ray surveys preferentially detect TDEs around low-mass black holes, while hard X-ray surveys are needed to find the high-mass population — a selection effect that must be folded into TDE rate calculations.
  • The rapid appearance of hard X-rays in high-mass TDEs (within weeks) means that coronal formation can be much faster than previously inferred from low-mass events, tightening constraints on coronal physics.
  • The radio non-detections of the two new TDEs, despite X-ray luminosities that would predict radio emission via the Fundamental Plane, suggest that TDE coronae may be more radiatively efficient or jets weaker than in X-ray binaries, requiring further monitoring to test for delayed jet launch.
  • The bimodality in peak blackbody luminosity/radius among featureless TDEs — if real — points to two distinct physical regimes that suppress line formation, which future UV spectroscopy can directly probe.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The claimed mass segregation could alternatively be driven by a soft-X-ray visibility bias: at fixed Eddington ratio, a 10^8 solar mass disk's thermal peak lies in the EUV, so a soft-state high-mass TDE would be nearly invisible in the 0.3–2 keV band. The paper acknowledges this but does not quantify it; if this selection effect dominates, the inferred universal transition threshold would be weake
  • A testable extension: if the ṁ = 0.03 threshold is real, then X-ray-selected TDEs around intermediate-mass black holes should show a sharp spectral transition at a predictable time based on their black hole mass and inferred fallback rate. Monitoring a larger sample with uniform X-ray cadence could directly verify the t_tr ∝ M_BH^{-3/4} scaling.
  • The authors' interpretation implies that TDEs can serve as scaled-up analogs of X-ray binary state transitions, but the fast transition duration (days to tens of days in TDEs vs. hours in XRBs) remains unexplained — a theoretical gap that future disk simulations might address.
  • If the two subclasses of featureless TDEs represent distinct line-suppression mechanisms, then their luminosity and radius distributions should correlate with outflow velocity measurements from UV spectroscopy; this could be tested with JWST or HST observations of a larger sample.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

4 major / 5 minor

Summary. This paper presents multi-wavelength observations of two luminous featureless TDEs, AT2024kmq and AT2024lhc, hosted by ~1e8 Msun black holes. It reports early, luminous, rapidly variable hard X-ray emission (minimum 1.3 hr and 4.8 hr variability), interprets the X-ray source as a compact corona, and uses radio nondetections to rule out J1644-like jets. The paper also compiles a 49-object comparison sample of ZTF TDEs and reports statistically significant bimodality in the peak blackbody luminosity and radius of the featureless subclass. Finally, using a 30-TDE eROSITA-selected sample, it finds that X-ray spectral evolution is mass-segregated (low-MBH soft, intermediate transitions, high-MBH hard from the outset) and interprets this as evidence that TDEs undergo a soft-to-hard state transition at mdot ~ 0.03 mdot_Edd, confirming a theoretical prediction based on the scaling t_tr ∝ M_BH^{-3/4}.

Significance. If the central state-transition claim holds, the paper would unify TDE accretion with X-ray binary state transitions and establish a mass-dependent framework for TDE X-ray detectability. The manuscript's strengths are the detailed, multi-instrument X-ray spectral analysis; the bootstrap test for bimodality; the construction of a well-defined eROSITA comparison sample; and the population-synthesis check with the FitTeD code. The radio limits and host-galaxy AGN constraints are also carefully presented. However, the central claim is not yet established because the observed mass segregation may be a bandpass selection effect, and the key theoretical scaling is unpublished. The paper is a useful contribution but requires additional quantitative work before it can be regarded as a confirmation.

major comments (4)
  1. [§4.2.1, Fig. 14] The mass segregation of X-ray spectral states may be an artifact of eROSITA's soft-band selection. The paper itself notes (paragraph beginning 'We note that at fixed Eddington ratio...') that high-MBH soft-state disks peak in the EUV and would be undetectable, so such systems would appear only when they become hard. The analysis does not quantify this: it does not compute the eROSITA detection probability as a function of MBH and spectral state, nor does it include the 19 non-detected TDEs in the mass-segregation comparison. Without a forward model of the selection, the conclusion that the data 'confirm' the mdot=0.03 prediction is not supported; it is consistent with the null hypothesis that the sample is simply visibility-limited.
  2. [§4.2.1, Eq. (6)] The central theoretical scaling t_tr ≈ 4000 d ... M_BH^{-3/4} is attributed to 'Mummery in prep.' This is unpublished work by a co-author, and the population-synthesis details (sampling distributions for stellar and disk parameters, the FitTeD code version) are not fully specified. Since the paper's headline claim is that the observed mass segregation 'confirms the theoretical prediction,' the derivation of Eq. (6) and the simulation setup must be available for independent scrutiny. At minimum, the derivation should be included in an appendix or the manuscript should cite a published source.
  3. [§4.2, Table 2; Abstract; §5] The abstract and conclusion state that the rapid variability supports a compact corona of ≲10 rg for both events. However, the 4.8 hr variability of AT2024lhc corresponds to cΔt ≈ 35 rg for MBH≈10^8 Msun, so the ≲10 rg limit is only justified for AT2024kmq's 1.3 hr timescale. The text in §4.2 says 'The rapid X-ray variability therefore constrains the X-ray emitting region to ≲10 rg' after citing both timescales, which conflates the two. The claim should be qualified to apply only to the object with the 1.3 hr variability, or the physical argument (e.g., the emitting region is much smaller than cΔt) should be made explicit.
  4. [§4.2.1, Figs. 15–16] The theoretical comparison uses mdot_crit = 0.03 as an input parameter, not as a fitted value. The population synthesis shows that this assumed threshold yields mass-segregated transition times consistent with the data, but it does not test whether other values of mdot_crit (or the bandpass selection effect alone) can reproduce the observed segregation. A direct quantitative test would be to compare the predicted t_tr(MBH) with the observed transition times of the intermediate-mass objects (e.g., AT2020ocn, AT2021ehb) without assuming the threshold a priori. As presented, the agreement does not constitute a confirmation of the 0.03 value.
minor comments (5)
  1. [§5 and §4.2.1] The conclusion says the result 'confirms the theoretical prediction of Mummery & Balbus (2021b)', but §4.2.1 states that the mass-segregation result was 'predicted by Mummery & Balbus (2021a)'. Please correct the citation.
  2. [§3.7] The HST spectrum shows that a single blackbody underestimates the FUV flux. The paper still uses the blackbody parameters from photometry in later analyses. This is a known systematic, but it would be useful to quote the updated Tbb/Rbb from the joint fit in Section 4.1 when discussing the bimodality.
  3. [§4.2.1] The classification 'soft (Γ>4)' is unusual because power-law photon indices >4 are rarely physical. Please clarify whether these are eROSITA hardness ratios converted to an equivalent photon index, and note the large uncertainties in this regime.
  4. [Fig. 13] The y-axis label 'LX (erg s-1)' and the color coding by Γ are clear, but the legend for the state categories (soft/intermediate/hard) is small; consider making it more prominent.
  5. [§3.4.6] The variability criterion requires a flux ratio exceeding a factor of two; the choice is reasonable but should be justified, as shorter-timescale variability with smaller amplitude may be missed. A brief justification would help.

Circularity Check

1 steps flagged

Mass segregation 'confirmation' of the ṁ=0.03 transition is partially circular: the eROSITA-selected sample is shaped by the same Mummery & Balbus bandpass effect used to explain high-mass hardness, and Eq. 6 relies on unpublished co-author work.

specific steps
  1. other [§4.2.1 (paragraph beginning 'We note that at fixed Eddington ratio...'); used in §5 conclusion]
    "Consequently, even if a M_BH∼10^8 M⊙ TDE remains above the ṁ∼0.03 threshold and has not yet formed a corona, it would likely evade detection in soft X-ray surveys. However, once these high-mass systems transition into the hard (coronal) state, they will become X-ray detectable again."

    The eROSITA comparison sample is selected on X-ray detection: 11 of 30 have eROSITA sources, and the remaining 19 have limits <10^43 erg/s. This quoted passage says that a high-mass soft-state TDE would be invisible to that selection and only becomes detectable after it goes hard. The observed class 'hard/intermediate throughout' at M_BH∼10^8 is therefore a detectability class, not an independent state-transition class. Using the mass segregation of this detection-selected sample as evidence for a soft-to-hard transition at ṁ=0.03 is circular: the same bandpass theory predicts exactly this pattern even if no transition at 0.03 occurred. The paper does not quantify the bias (no M_BH distribution of the 19 non-detections, no sensitivity correction for high-mass soft disks), so the conclusion

full rationale

Most of the paper—the detailed observations of AT2024lhc and AT2024kmq (spectra, X-ray variability, radio limits, corona size, blackbody fits)—is self-contained data analysis and is not circular. The circularity is concentrated in the population-level 'confirmation' in §4.2.1/§5. The eROSITA-based comparison sample is detection-selected, and the paper itself states the Mummery & Balbus (2021b) bandpass effect makes high-mass soft-state TDEs invisible; therefore the observed mass segregation (low M_BH soft, high M_BH hard from the outset) is the expected selection outcome of the same theoretical framework, not an independent test of the ṁ=0.03 transition threshold. The paper acknowledges this possibility but does not quantify it. Separately, the quantitative t_tr scaling (Eq. 6) is attributed to 'Mummery in prep' (a co-author) and validated with FitTeD by the same group; this is a self-citation support concern, but the heuristic Eqs. (4)–(5) are self-contained, so the decisive circularity is the selection effect. Score 6 reflects partial circularity: the central population claim is not forced by a fitted parameter, but the 'confirmation' is not established because the observation is shaped by the same theory's bandpass selection.

Axiom & Free-Parameter Ledger

7 free parameters · 7 axioms · 0 invented entities

The central interpretation pulls in standard α-disk theory (α, h/r, η, f_d), the external XRB threshold 0.03, the unpublished scaling relation Eq. 6, and the assumption that eROSITA-selected X-ray detections trace the true accretion state. The blackbody fits that feed the bimodality claim rely on single-temperature Planck functions that the paper itself shows underestimate FUV. No new physical entities are introduced; the corona and truncated disk are standard accretion constructs.

free parameters (7)
  • Critical Eddington ratio ṁ_crit = 0.03
    Threshold for soft-to-hard transition, taken from XRB observations (Maccarone 2003; Dunn et al. 2010); not fitted to TDE data, but the central interpretive number.
  • Viscosity parameter α = 0.1
    Assumed in Eq. 6 and FitTeD population synthesis; typical XRB value (King et al. 2007).
  • Disk aspect ratio h/r (θ) = 0.1
    Assumed in Eq. 6; affects t_tr by θ^{-1/2}.
  • Radiative efficiency η = 0.1
    Assumed in Eq. 6; standard thin-disk value.
  • Disk formation fraction f_d = 0.1
    Assumed fraction of stellar mass forming the disk; enters t_tr as f_d^{3/4}.
  • Blackbody T_bb and R_bb per epoch = log T_bb ~ 3.8–4.4; log R_bb ~ 14.5–15.5
    Fitted to UV/optical photometry; central to the bimodality claim and SED. Also includes per-epoch excess variance σ0.
  • K-means bimodality criteria = silhouette > 0.7; Cohen's d > 3.0; >80% bootstraps
    Hand-chosen thresholds for declaring bimodality in the 49-TDE sample.
axioms (7)
  • domain assumption Standard α-disk accretion theory and t^{-5/3} fallback describe TDE disk evolution
    Used throughout §4.2 to interpret the mass segregation and transition timescale.
  • domain assumption M_BH–σ* (Kormendy & Ho 2013) and M_BH–M_gal (Yao et al. 2023) relations apply to TDE host galaxies
    Used in §4.1 and §4.2.1 to estimate black hole masses for the comparison samples.
  • domain assumption A single-temperature blackbody adequately represents the UV/optical SED
    Used for Lbb/Rbb in the bimodality analysis; the paper itself shows in §3.7 that a single blackbody underestimates FUV flux.
  • domain assumption eROSITA-detected TDEs are representative of the accretion-state distribution; sparse Γ classifications trace the true state
    The 11 detected TDEs in the eROSITA sample are divided into soft/intermediate/hard based on sparse snapshots; non-detections are not used in the state classification.
  • ad hoc to paper Equation (6) (Mummery in prep) gives the correct transition timescale
    The central scaling t_tr ∝ M_BH^{-3/4} is attributed to an unpublished manuscript by a co-author and is not derived in this paper.
  • domain assumption No pre-existing radiative-mode AGN contributes to the observed emission
    Based on [O III] and host X-ray upper limits in §2.4; used to argue the transients are TDEs rather than AGN variability.
  • domain assumption Host extinction is negligible for the TDE SED
    Assumed in §3.6 based on small fitted E(B-V) values and the lack of extra X-ray absorption.

pith-pipeline@v1.3.0-alltime-deepseek · 37026 in / 18487 out tokens · 156367 ms · 2026-08-02T20:58:19.774775+00:00 · methodology

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Cite this review

Pith. "Pith review of AT2024lhc and AT2024kmq in the landscape of featureless tidal disruption events." pith.science (2026). https://pith.science/paper/5Z6L6Z27

@misc{pith2026260221624,
  author       = {Pith},
  title        = {Pith review of: AT2024lhc and AT2024kmq in the landscape of featureless tidal disruption events},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/5Z6L6Z27}},
  note         = {Machine review of arXiv:2602.21624}
}
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read the original abstract

We study AT2024kmq and AT2024lhc, two tidal disruption events (TDEs) with blue featureless spectra associated with high-mass black holes ($M_{\rm BH}\sim 10^8\,M_\odot$). Both events show optical precursors consistent with shock dissipation from stream self-intersection. Their X-ray emission is luminous ($L_{\rm X}\sim 10^{44}\,{\rm erg\,s^{-1}}$), highly variable (with minimum observed variability timescales of 1.3\,hr and 4.8\,hr for factor of $\sim3$ flux changes), long-lasting ($>1\,\rm yr$), emerging no later than the optical peak, and well characterized by power-laws with $1.7<\Gamma<3$ (where $f_\nu \propto \nu^{1-\Gamma}$). The X-ray properties and radio non-detections support a compact corona ($\lesssim 10 r_{\rm g}$) producing Comptonized X-ray emission. Using all published featureless TDEs, we find statistically significant bimodality in the distribution of their peak UV/optical blackbody luminosities and radii. We assemble a comparison TDE sample with early-time X-ray observations with eROSITA, in which we find different $M_{\rm BH}$ distributions in TDEs with different X-ray spectral evolution properties: low-mass black holes ($M_{\rm BH} \sim 10^6 M_\odot$) remain soft ($\Gamma>4$) within $t\lesssim 2$\,yr, intermediate masses ($\sim 10^7 M_\odot$) transition from soft to hard at $\sim$1 yr, while high masses ($\sim 10^8 M_\odot$) are hard ($1.5<\Gamma\lesssim 3$) from the outset. We interpret this result as evidence that the soft-to-hard state transition in TDEs occurs at the critical threshold of $\dot{M}_{\rm acc} \sim 0.03 \dot M_{\rm Edd}$ (similar to X-ray binaries), using the fact that the transition timescale predicted by simple disk theory scales with black hole mass as $t_{\rm tr}\propto M_{\rm BH}^{-3/4}$.

Figures

Figures reproduced from arXiv: 2602.21624 by Andrew Drake, Andrew Mummery, Anna Y. Q. Ho, Ashish A. Mahabal, Ben Rusholme, Charlotte R. Angus, Daniel A. Perley, Dheeraj R. Pasham, Elias Kammoun, Erica Hammerstein, Eric R. Coughlin, Genevieve Schroeder, George Helou, Jacob R. Wise, Jean Somalwar, Jesper Sollerman, Joahan C. Jaimes, Joheen Chakraborty, Josiah Purdum, Kate D. Alexander, K.-Ryan Hinds, Mansi M. Kasliwal, Marat Gilfanov, Matteo Lucchini, Matthew J. Graham, Matt Nicholl, Michael W. Coughlin, Muryel Guolo, Natalie LeBaron, Olivia Aspegren, Pavel Medvedev, Raffaella Margutti, Rashid Sunyaev, R. Michael Rich, Ryan Chornock, Wenbin Lu, Xander J. Hall, Xiaoshan Huang, Xinyue Sheng, Xinze Guo, Yuhan Yao, Zo\"e McGrath.

Figure 1
Figure 1. Figure 1: UV, optical and X-ray evolution of AT2024lhc. UV and optical light curves are shown in the upper panel, with epochs of optical spectroscopy marked with letter “S”, and the epoch of HST spectroscopy marked with a vertical dotted line. Solid points represent detections above 3𝜎 in the optical and above 2𝜎 in the UV; semitransparent downward triangles indicate 3𝜎 upper limits. The observed 0.3–10 keV X-ray li… view at source ↗
Figure 2
Figure 2. Figure 2: UV, optical and X-ray evolution of AT2024kmq. We only indicate epochs of optical spectroscopy and radio observations first presented in this work, see Ho et al. (2025) for earlier observations. spectroscopy approach for reliable estimation of faint-source light curves outlined in Section 2.1 of Chakraborty et al. (2024), which we summarize here. We divided the data into continuous good-time in￾tervals (GTI… view at source ↗
Figure 3
Figure 3. Figure 3: Early-phase optical light curves of AT2024kmq and AT2024lhc in flux space, showing the precursor emission detected in both events. Solid and semitransparent points represent > 3𝜎 detections and other observations, respectively. The dashed horizontal line at zero is the average value pre￾transient. 3000 4000 5000 6000 7000 8000 Rest-frame Wavelength (Å) Scale d f + offset +153 d, Kast +161 d, ALFOSC +328 d,… view at source ↗
Figure 4
Figure 4. Figure 4: Optical spectra of AT2024kmq obtained after October 2024 (see Ho et al. 2025 for earlier epochs). Strong telluric features in the ALFOSC spectrum are masked. No prominent broad emission lines characteristic of TDEs are detected. source region of 𝑟src = 2.0 ′′ centered on the apparent X-ray position of each object. A total of 65 and 193 (0.5–8 keV) counts are detected within the source regions of AT2024kmq … view at source ↗
Figure 6
Figure 6. Figure 6: Host–transient decomposition for the optical spectra of AT2024lhc. Galactic extinction-corrected spectra (black) are modeled as the sum of host galaxy emission (gray) and blackbody continuum (blue), with the total model shown in red. Residuals show no significant broad features, confirming AT2024lhc as spectroscopically featureless from 𝑡rest = 42 d to 262 d. MNRAS 000, 1–21 (2026) [PITH_FULL_IMAGE:figure… view at source ↗
Figure 8
Figure 8. Figure 8: Radio upper limits of AT2024kmq, AT2024lhc, compared with the sample of optically overluminous TDEs presented in Yao et al. (2025). The blue lines show model radio light curves for a jet with the same intrinsic properties as the best-fit model of the jetted TDE Swift J1644+57 (Beniamini et al. 2023), viewed at different angles. Assuming all other parameters are identical, even the most off-axis jet models … view at source ↗
Figure 9
Figure 9. Figure 9: Evolution of the UV/optical blackbody properties of AT2024lhc and AT2024kmq. Epochs where both 𝑇bb and 𝑅bb are fitted are shown in black, where solid and hollow markers indicate epochs with and without UVOT observations, respectively. Epochs scaled assuming fixed 𝑇bb are shown in gray. The vertical dashed lines mark epochs where detailed broadband SEDs are presented in [PITH_FULL_IMAGE:figures/full_fig_p0… view at source ↗
Figure 10
Figure 10. Figure 10: HST UV spectrum of AT2024lhc. The unbinned and binned data are shown in thick black and thin gray lines, respectively. Regions affected by strong geocoronal absorption or emission have been masked. The blue lines show the blackbody model fitted to both spectroscopy and photometry, while the orange lines show the model fitted to photometry only. 𝜈rest = 1017 Hz and 1018.5 Hz, we integrate beneath the best-… view at source ↗
Figure 11
Figure 11. Figure 11: Broadband SEDs of AT2024kmq and AT2024lhc at representative epochs. In each panel, the horizontal dashed and dotted lines show 10−2𝐿Edd and 10−3𝐿Edd for 108 𝑀⊙ BHs, where 𝐿Edd = 1.26 × 1038 (𝑀BH/𝑀⊙ ) erg s−1 . 5 6 7 8 9 log(MBH/M ) 10 43 10 44 10 45 Lbb (erg/s) 18iih 18jbv 19cmw 20pj 20ysg 20wey 20acka 21axu 21ehb 21yzv 20qhs 20riz 19teq 20ddv 20ocn 20ohl 22gri 22hvp 21aeou 24lhc 24kmq 19wzc (a) 10 15 Rbb… view at source ↗
Figure 12
Figure 12. Figure 12: AT2024kmq and AT2024lhc compared with other TDEs, color-coded by spectral subclasses. Panel (a): TDEs in the phase space of peak 𝐿bb and black hole mass, where 𝑀BH is directly estimated using host-galaxy scaling relations. Panel (b): TDEs in the phase space of peak 𝐿bb and 𝑅bb at peak luminosity. Dotted lines show constant temperatures of 𝑇bb = [1, 2, 3, 4, 5] × 104 K. Panel (c): Distribution of 𝑀BH for T… view at source ↗
Figure 13
Figure 13. Figure 13: X-ray light curves of 11 ZTF TDEs with eROSITA detections within 6 months after first optical light. The data points are color-coded by the X-ray spectral power-law index Γ. function of black hole mass 𝑚¤ peak ≡ 𝑀¤ acc,peak 𝑀¤ Edd ≈ 𝑀disk 𝑡visc × 1 𝑀¤ Edd ∝ 1 𝑀BH . (5) With a lower 𝑚¤ peak and a similar evolutionary timescale, higher mass black hole TDEs will have 𝑚¤ peak ∼ 0.01 at earlier times, making t… view at source ↗
Figure 15
Figure 15. Figure 15: The time for a variety of different simulated TDE disk systems to fall to an Eddington ratio of 0.03 (see text for simulation details), as a function of black hole mass. The blue, orange and red contours show 1, 2 and 3 𝜎 confidence intervals respectively (i.e., they contain 68.3%, 95.4% and 99.7% of the points). The black dashed curve shows the analytical scaling argument discussed in the text 𝑡tr ∝ 𝑀 −3… view at source ↗
Figure 16
Figure 16. Figure 16: Upper: one dimensional probability distributions of the transition time for disk systems within a factor two of the black hole masses denoted on the plot. We see that 𝑀BH ∼ 106𝑀⊙ TDE systems typically take ∼ 103 d (multiple years), 𝑀BH ∼ 107𝑀⊙ systems typically transition after ∼ 1 yr, while 𝑀BH ∼ 108𝑀⊙ systems transition rapidly at 𝑡 ≲ 100 d, and will likely only ever be observed in a harder state. Lower… view at source ↗

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Forward citations

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  4. Early Near-Infrared Excess and Rapid Disk-Corona Evolution in the Tidal Disruption Event 2024aepd

    astro-ph.HE 2026-07 conditional novelty 5.0

    TDE 2024aepd exhibits an early near-infrared excess consistent with free-free emission from a reprocessing outflow, and a rapid disk-to-corona X-ray transition.

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Works this paper leans on

3 extracted references · cited by 3 Pith papers

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    The dashed lines show the best-fit absorbed power-law model

    AT2024kmq tobs = 257 d 0.5 1 2 3 5 10 20 Erest (keV) 0 1 2Ratio AT2024kmq tobs = 279 d 0.5 1 2 3 5 10 Erest (keV) Figure A1.Joint spectral fitting between NuSTAR and XRT. The dashed lines show the best-fit absorbed power-law model. ogy, Pasadena, CA 91125, USA 31 CaltechOpticalObservatories,CaliforniaInstituteofTechnology, Pasadena, CA 91125, USA APPENDIX...

    2026

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    Name obsID Exp

    Table B2.NuSTAR observation log and joint spectral fitting with XRT. Name obsID Exp. Start Time𝑡 obs 𝑡rest FPMA Count RateΓ𝑓 X cstat/dof (ks) (UT) (d) (d) (count s −1) (10 −13 ergs−1 cm−2) AT2024kmq 81001608002 𝑎 67.3 2024-11-02.1 157 1320.0008±0.0002 2.59 +0.17 −0.18 3.68+0.87 −0.66 31.15/33 81002638002𝑏 23.0 2025-01-29.5 245 2060.0026±0.0004 1.63 +0.20 ...

    arXiv 2024