The Role of the Volume in Black Hole Thermodynamics
Pith reviewed 2026-06-30 04:48 UTC · model grok-4.3
The pith
The first law of black hole thermodynamics holds for energy E but not F because only the associated Killing vector keeps unvarying components.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By defining the conserved quantity H^I_χ associated with a Killing vector χ, where E equals H^I_ξ and F equals H^I_β, the first law is satisfied if both χ^a and the background anti-de Sitter metric have unvarying components. This holds for ξ^a but not β^a, which explains why the first law works for E but not F. The vector volume V_C appears in the β-associated Smarr relation due to simplifications related to the principal conformal Killing-Yano tensor h.
What carries the argument
The conserved quantity H^I_χ defined by adapting the Barnich-Compère prescription to a Killing vector χ, which yields the AMD energies E and F for the specific choices of ξ and β.
Load-bearing premise
The adapted Barnich-Compère definition of the conserved quantity applies directly to the Kerr-AdS black holes with the given choices of Killing vectors and without further adjustments.
What would settle it
Compute the first law variation explicitly for H^I_β and check if it fails to hold when the components of β vary with the black hole parameters.
Figures
read the original abstract
Gibbons et al. [arXiv:hep-th/0408217] found the energy $E$ of Kerr--anti-de Sitter black holes by integrating the first law of black hole thermodynamics. They found that $E$ corresponds to the Ashtekar--Magnon--Das (AMD) energy associated with an asymptotically nonrotating frame, whereas the AMD ``energy'' which I will call $F$ associated with an asymptotically rotating frame does not satisfy the first law. In Cveti\v{c} et al. [arXiv:1012.2888], the first law was extended by interpreting $E$ as an enthalpy and $\Lambda$ as being proportional to a pressure. The term conjugate to the pressure was then interpreted as the ``thermodynamic volume'' $V_{th}$. Associated with the first law (with varying pressure) is a Smarr relation for $E$. The Smarr relation for $F$ also exists, and the term conjugate to the pressure in that Smarr relation is the ``geometric volume'' $V_{geo}$, shown in [arXiv:1310.1935] to be equal to the vector volume $V_C$ of the black hole. To address why it is necessary to use $E$ rather than $F$ to have a viable first law but $V_C$ appears naturally in the Smarr relation associated with $F$ rather than $E$, I adapt Barnich and Comp\`ere [arXiv:gr-qc/0412029], by defining a conserved quantity $H^I_\chi$ associated with Killing vector $\chi$. $E$ and $F$ are given by $H^I_\xi$ and $H^I_\beta$ respectively where $\xi$ is asymptotically hypersurface-orthogonal and $\beta$ is proportional to the divergence of the Principal Conformal Killing--Yano tensor $\boldsymbol{h}$. I show that the first law will be satisfied by $H^I_\chi$ if both $\chi^a$ and the background anti-de Sitter metric have unvarying components, which holds for $\xi^a$ but not $\beta^a$, explaining why the first law works for $E$ but not $F$. I show that $V_C$ appears in the $\beta$-associated Smarr relation due to simplifications related to $\boldsymbol{h}$.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper claims that the first law holds for the AMD energy E but not the rotating-frame quantity F in Kerr-AdS black holes because E = H^I_ξ and F = H^I_β, where H^I_χ is an adaptation of the Barnich-Compère conserved quantity. The first law is satisfied by δH^I_χ precisely when both the Killing vector χ^a and the fixed AdS background have unvarying components (true for the asymptotically hypersurface-orthogonal ξ but not for β proportional to div h). This distinction explains the thermodynamic viability of E (interpreted as enthalpy) versus F, while V_C enters the β-Smarr relation via simplifications from the PCKY tensor h.
Significance. If the adaptation of Barnich-Compère is valid without extraneous terms and the unvarying-components criterion follows directly, the work supplies a unified kinematic explanation for the choice of E over F in extended black-hole thermodynamics and for the distinct roles of V_th and V_geo = V_C. It connects the first-law and Smarr structures to the asymptotic properties of the Killing vectors and the background metric, potentially clarifying why the pressure term appears differently in the two cases.
major comments (2)
- The central claim rests on the adaptation of the Barnich-Compère definition of H^I_χ to the Kerr-AdS setting and the direct correspondence E = H^I_ξ, F = H^I_β. The manuscript must explicitly verify that this adaptation introduces no additional boundary or variation terms when χ = β (whose components vary), as this is the load-bearing step for why δH^I_β fails the first law while δH^I_ξ succeeds.
- The assertion that δH^I_χ obeys the first law exactly when both χ^a and the background AdS metric have unvarying components requires a step-by-step derivation from the definition of H^I_χ, including explicit checks against the concrete forms of ξ and β in the Kerr-AdS metric (and against the equations of the three cited papers). Without this derivation or the checks, the sufficiency of the unvarying-components condition remains unverified.
minor comments (2)
- Notation for the vectors ξ and β, and for the PCKY tensor h, should be introduced with explicit definitions or references to their components in the Kerr-AdS coordinates before the statements about unvarying components.
- The abstract refers to 'the section defining H^I_χ' implicitly; the manuscript should number the relevant equations for the definition and the variation δH^I_χ so that the first-law condition can be traced directly.
Simulated Author's Rebuttal
Thank you for the constructive feedback. We agree that the adaptation and the unvarying-components criterion require more explicit verification and will revise the manuscript to include the requested step-by-step derivations and checks.
read point-by-point responses
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Referee: The central claim rests on the adaptation of the Barnich-Compère definition of H^I_χ to the Kerr-AdS setting and the direct correspondence E = H^I_ξ, F = H^I_β. The manuscript must explicitly verify that this adaptation introduces no additional boundary or variation terms when χ = β (whose components vary), as this is the load-bearing step for why δH^I_β fails the first law while δH^I_ξ succeeds.
Authors: We agree this verification is necessary. The revised manuscript will add an explicit section adapting the Barnich-Compère formula to Kerr-AdS, with direct computation showing that no extraneous boundary or variation terms appear for χ = β. This will confirm the distinction between δH^I_ξ and δH^I_β arises only from the component variation. revision: yes
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Referee: The assertion that δH^I_χ obeys the first law exactly when both χ^a and the background AdS metric have unvarying components requires a step-by-step derivation from the definition of H^I_χ, including explicit checks against the concrete forms of ξ and β in the Kerr-AdS metric (and against the equations of the three cited papers). Without this derivation or the checks, the sufficiency of the unvarying-components condition remains unverified.
Authors: We will include a new derivation subsection in the revision. Starting from the definition of H^I_χ, we derive the first-law condition and verify it holds iff both χ^a and the AdS background have unvarying components. Explicit checks will use the concrete Kerr-AdS expressions for ξ and β, cross-referenced to the equations in the three cited papers. revision: yes
Circularity Check
No circularity: derivation adapts external Barnich-Compère definition to Kerr-AdS and derives unvarying-components condition independently
full rationale
The paper's central steps consist of (1) adapting the Barnich-Compère conserved quantity H^I_χ from the cited external reference arXiv:gr-qc/0412029, (2) identifying E = H^I_ξ and F = H^I_β using the given vector definitions, and (3) showing that δH^I_χ obeys the first law precisely when both χ^a and the fixed AdS background have unvarying components. These steps rely on external citations (Gibbons et al., Cvetič et al., Barnich-Compère) whose results are not reproduced or fitted inside the present work; the unvarying-components criterion is presented as a derived property of the adapted definition rather than a self-fit or self-citation chain. No self-definitional loops, fitted inputs renamed as predictions, or load-bearing self-citations appear. The derivation therefore remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (2)
- domain assumption Existence of a conserved charge H^I_χ associated with any Killing vector χ via the Barnich-Compère construction
- domain assumption The background AdS metric and the chosen Killing vector can be compared for component invariance
Reference graph
Works this paper leans on
-
[1]
L. F. Abbott and S. Deser, Nucl. Phys. B195(1) 76–96 (1982)
1982
-
[2]
M. Abdelqader and K. Lake, Phys. Rev. D86124037 (2012), [arXiv:1207.5496]
work page internal anchor Pith review Pith/arXiv arXiv 2012
-
[3]
S. Ackay and R. A. Matzner, Class. Quant. Grav.28085012 (2011), [arXiv:1011.0479]
work page internal anchor Pith review Pith/arXiv arXiv 2011
-
[4]
Thermodynamics of rotating black holes and black rings: phase transitions and thermodynamic volume
N. Altamirano, D. Kubizˇ nak, R. B. Mann and Z. Sherkatghanad, Galaxies289–159 (2014), doi:10.3390/galaxies2010089; also available as [arXiv:1401.2586]
work page internal anchor Pith review Pith/arXiv arXiv doi:10.3390/galaxies2010089 2014
-
[5]
T. M. Apostol,Calculus, Volume 2, second edition (Wiley, 1969)
1969
-
[6]
Ashtekar and A
A. Ashtekar and A. Magnon, Class. Quant. Grav.1L39 (1984)
1984
-
[7]
Asymptotically Anti-de Sitter Space-times: Conserved Quantities
A. Ashtekar and S. Das, Class. Quant. Grav.17L17 (2000), [arXiv:hep-th/9911230]
work page internal anchor Pith review Pith/arXiv arXiv 2000
-
[8]
A. Ashtekar, T. Pawlowski and C. Van Den Broeck, Class. Quant. Grav.24625 (2007), [arXiv:gr- qc/0611049]
-
[9]
The volume of stationary black holes and the meaning of the surface gravity
W. Ballik and K. Lake, (2010), [arXiv:gr-qc/1005.1116v3]
work page internal anchor Pith review Pith/arXiv arXiv 2010
-
[10]
The Vector Volume and Black Holes
W. Ballik and K. Lake, Phys. Rev. D88104038 (2013), [arXiv:1310.1935]
work page internal anchor Pith review Pith/arXiv arXiv 2013
-
[11]
J. M. Bardeen, B. Carter and S. W. Hawking, Comm. Math. Phys.31161 (1973)
1973
-
[12]
Covariant theory of asymptotic symmetries, conservation laws and central charges
G. Barnich and F. Brandt, Nucl. Phys. B6333–82 (2002), [arXiv:hep-th/0111246]
work page internal anchor Pith review Pith/arXiv arXiv 2002
-
[13]
Generalized Smarr relation for Kerr AdS black holes from improved surface integrals
G. Barnich and G. Comp` ere, Phys. Rev. D71044016 (2005), Erratum-idi.D71:029904 (2006), [arXiv:gr-qc/0412029]. 417
work page internal anchor Pith review Pith/arXiv arXiv 2005
-
[14]
On Thermodynamics of AdS Black Holes in Arbitrary Dimensions
A. Belhaj, M. Chabab, H. El Moumni, and M. Sedra, Chin. Phys. Lett.29100401 (2012), [arXiv:1210.4617]
work page internal anchor Pith review Pith/arXiv arXiv 2012
-
[15]
M. Blagojevi´ c and B. Cvetkovi´ c, Phys. Rev. D101, no.8, 084023 (2020) [arXiv:2002.05029]
- [16]
-
[17]
H. W. Brinkmann, Math. Ann.94119—145 (1925)
1925
- [18]
-
[19]
M. M. Caldarelli, J. Camps, B. Gout´ eraux, B. and K. Skenderis, Phys. Rev. D87061502(R) (2013), [arXiv:1211.2815]
work page internal anchor Pith review Pith/arXiv arXiv 2013
- [20]
- [21]
-
[22]
T. de L. Campos, M.C. Baldiotti, C. Molina, [arXiv:2605.16536]
work page internal anchor Pith review Pith/arXiv arXiv
-
[23]
Carminati and R
J. Carminati and R. G. McLenaghan, J. Math. Phys.32(11) 3135–3140 (1991)
1991
-
[24]
Carter, Comm
B. Carter, Comm. Math. Phys.10280–310 (1968)
1968
-
[25]
Black Hole Equilibrium States
B. Carter, “Black Hole Equilibrium States” (FromLes Houches1972, ed. by DeWitt)
-
[26]
W. Chen, H. L¨ u, C. N. Pope, Class. Quant. Grav.235323–5340 (2006), [arXiv:hep-th/0604125]
work page internal anchor Pith review Pith/arXiv arXiv 2006
-
[27]
W. Chen, H. L¨ u, Phys. Lett. B658158–163 (2008), [arXiv:0705.4471]
work page internal anchor Pith review Pith/arXiv arXiv 2008
-
[28]
Cosmological constant is a conserved charge
D. Chernyavsky and K. Hajian, Class. Quant. Grav.35(12) 125012 (2018), [arXiv:1710.07904]
work page internal anchor Pith review Pith/arXiv arXiv 2018
-
[29]
M. Christodoulou and C. Rovelli, Phys. Rev. D91, 064046 (2015), [arXiv:1411.2854]
work page internal anchor Pith review Pith/arXiv arXiv 2015
-
[30]
On the volume inside old black holes
M. Christodoulou and T. De Lorenzo, Phys. Rev. D94, 104002 (2016), [arXiv:1604.07222]
work page internal anchor Pith review Pith/arXiv arXiv 2016
-
[31]
P. T. Chru´ sciel, J. Jezierski and J. Kijowski, Phys. Rev. D92, 084030 (2015), [arXiv:1507.03868]. 418
work page internal anchor Pith review Pith/arXiv arXiv 2015
-
[32]
An introduction to the mechanics of black holes
G. Comp` ere, “An introduction to the mechanics of black holes” (2006), [arXiv:gr-qc/061129]
2006
-
[33]
Noether charge, black hole volume, and complexity
J. Couch, W. Fischler, P. H. Nguyen, JHEP1703119 (2017), [arXiv:1610.02038]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[34]
Black Hole Enthalpy and an Entropy Inequality for the Thermodynamic Volume
M. Cvetiˇ c, G. W. Gibbons, D. Kubizˇ n´ ak, and C. N. Pope, Phys. Rev. D84024037 (2011), [arXiv:1012.2888]
work page internal anchor Pith review Pith/arXiv arXiv 2011
-
[35]
S. Das, R. B. Mann, JHEP0008033 (2000), [arXiv:hep-th/0008028]
work page internal anchor Pith review Pith/arXiv arXiv 2000
-
[36]
Dereli and M
T. Dereli and M. G¨ urses, Phys. Lett. B171209 (1986)
1986
-
[37]
On the mass of a Kerr-anti-de Sitter spacetime in D dimensions
N. Deruelle and J. Katz, Class. Quant. Grav.22421 (2005), [arXiv:gr-qc/0410135]
work page internal anchor Pith review Pith/arXiv arXiv 2005
-
[38]
Comments on conformal masses, asymptotics backgrounds and conservation laws
N. Deruelle and J. Katz, Class. Quant. Grav.23753 (2006), [arXiv:gr-qc/0512077]
work page internal anchor Pith review Pith/arXiv arXiv 2006
-
[39]
B. P. Dolan, Class. Quant. Grav.28125020 (2011), [arXiv:1008.5023]
work page internal anchor Pith review Pith/arXiv arXiv 2011
-
[40]
B. P. Dolan, Class. Quant. Grav.28235017 (2011), [arXiv:1106.6260]
work page internal anchor Pith review Pith/arXiv arXiv 2011
-
[41]
B. P. Dolan, Phys. Rev. D84127503 (2011), [arXiv:1109.0198]
work page internal anchor Pith review Pith/arXiv arXiv 2011
- [42]
-
[43]
Thermodynamic Volumes and Isoperimetric Inequalities for de Sitter Black Holes
B. Dolan, D. Kastor, D. Kubizˇ n´ ak, R. B. Mann and J. Traschen, Phys. Rev. D87, 104017 (2013), [arXiv:hep-th/1301.5926]
work page internal anchor Pith review Pith/arXiv arXiv 2013
-
[44]
Black Rings, Supertubes, and a Stringy Resolution of Black Hole Non-Uniqueness
H. Elvang and R. Emparan, JHEP0311035 (2003), [arXiv:hep-th/0310008]
work page internal anchor Pith review Pith/arXiv arXiv 2003
-
[45]
A rotating black ring in five dimensions
R. Emparan and H. S. Reall, Phys. Rev. Lett.88101101 (2002), [arXiv:hep-th/0110260]
work page internal anchor Pith review Pith/arXiv arXiv 2002
-
[46]
V. P. Frolov and D. Kubizˇ n´ ak, Class. Quant. Grav.25154005 (2008), [arXiv:0802.0322]
work page internal anchor Pith review Pith/arXiv arXiv 2008
-
[47]
V. P. Frolov, P. Krtouˇ s, D. Kubizˇ n´ ak, Phys. Lett.B771254–6 (2017) [arXiv:1705.00943]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[48]
V. P. Frolov, P. Krtouˇ s, D. Kubizˇ n´ ak, Rev. Relativ.20:6 (2017), [arXiv:1705.05482]
work page internal anchor Pith review Pith/arXiv arXiv 2017
- [49]
-
[50]
S. Gao and R. M. Wald, Phys. Rev. D64084020 (2001), [arXiv:gr-qc/0106071]. 419
work page internal anchor Pith review Pith/arXiv arXiv 2001
- [51]
-
[52]
G. W. Gibbons, H. L¨ u, D.N. Page, C.N. Pope, J. Geom. Phys.5349–73 (2005), [arXiv:hep-th/0404008]
work page internal anchor Pith review Pith/arXiv arXiv 2005
- [53]
-
[54]
G. W. Gibbons, (2012), [arXiv:1201.2340]
work page internal anchor Pith review Pith/arXiv arXiv 2012
-
[55]
M. Golshani, M. M. Sheikh-Jabbari, V. Taghiloo, M. H. Vahidinia, [arXiv:2407.15994]. [56]GRTensorby P. Musgrave, D. Pollney and K. Lake is a package which runs within Maple. Some of the calculations used in this thesis usedGRTensorIIand some used the newerGRTensorIII(most recent version 2023). It is entirely distinct from packages distributed with Maple a...
-
[56]
S. Gunasekaran, R. B. Mann, and D. Kubizˇ n´ ak, JHEP1211110 (2012), [arXiv:1208.6251]
work page internal anchor Pith review Pith/arXiv arXiv 2012
-
[57]
Conserved Charges and First Law of Thermodynamics for Kerr-de Sitter Black Holes
K. Hajian, General Relativity and Gravitation48114 (2016), [arXiv:1602.05575]
work page internal anchor Pith review Pith/arXiv arXiv 2016
-
[58]
K. Hajian and M. M. Sheikh-Jabbari, Phys. Rev. D93044074 (2016), [arXiv:1512.05584]
- [59]
-
[60]
A Universal Smarr Formula via Coupling Constants
K. Hajian, B. Tekin and O. Ucanok, [arXiv:2511.22558]
work page internal anchor Pith review Pith/arXiv arXiv
-
[61]
N. Hamamoto, T. Houri, T. Oota and Y. Yasui, J. Phys. A: Math. Theor.40F177 (2006), [arXiv:hep- th/0611285]
-
[62]
D. A. Harville,Matrix Algebra From a Statistician’s Perspective(Springer-Verlag, 1997)
1997
-
[63]
S. W. Hawking, Nature248.5443 30–31 (1974)
1974
- [64]
-
[65]
S. W. Hawking and D. N. Page, Commun. Math. Phys.87577-588 (1983). 420
1983
-
[66]
S. A. Hayward, Class. Quant. Grav.153147 (1998), [arXiv:gr-qc/9710089]
work page internal anchor Pith review Pith/arXiv arXiv 1998
-
[67]
S. A. Hayward, Class. Quant. Grav.171749 (2000), [arXiv:gr-qc/9909070v2]
work page internal anchor Pith review Pith/arXiv arXiv 2000
-
[68]
S. A. Hayward, Phys. Rev. Lett.93251101 (2004), [arXiv:gr-qc/0404077]
work page internal anchor Pith review Pith/arXiv arXiv 2004
-
[69]
Extended phase space thermodynamics and P-V criticality of black holes with nonlinear source
S. Hendi and M. Vahidinia, (2012), [arXiv:1212.6128]
work page internal anchor Pith review Pith/arXiv arXiv 2012
-
[70]
Henneaux and C
M. Henneaux and C. Teitelboim, Commun. Math. Phys.98, 391–424 (1985)
1985
-
[71]
Henneaux and C
M. Henneaux and C. Teitelboim,Quantization of Gauge Systems(Princeton University Press, 1992)
1992
-
[72]
Comparison between various notions of conserved charges in asymptotically AdS-spacetimes
S. Hollands, A. Ishibashi and D. Marolf, Class. Quant. Grav.222881 (2005) [arXiv:hep-th/0503045]
work page internal anchor Pith review Pith/arXiv arXiv 2005
-
[73]
Houri, T
T. Houri, T. Oota and Y. Yasui, Phys. Lett. B656214–216 (2007)
2007
-
[74]
Generalized Kerr-NUT-de Sitter metrics in all dimensions
T. Houri, T. Oota and Y. Yasui, Phys. Lett. B666391–394 (2008), [arXiv:0805.0838]
work page internal anchor Pith review Pith/arXiv arXiv 2008
-
[75]
S. Hyun, J. Jeong, S. A. Park and S. H. Yi, JHEP04, 048 (2017) [arXiv:1702.06629]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[76]
Inverse of Vandermonde Matrix
“Inverse of Vandermonde Matrix” from ProofWiki, [https://proofwiki.org/wiki/Inverse_of_ Vandermonde_Matrix]
-
[77]
Israel, Phys
W. Israel, Phys. Rev. D2641 (1970)
1970
-
[78]
Israel,Differential Forms in General Relativity(Communications of the Dublin Institute for Ad- vanced StudiesANo, 26, Dublin, 1979)
W. Israel,Differential Forms in General Relativity(Communications of the Dublin Institute for Ad- vanced StudiesANo, 26, Dublin, 1979)
1979
-
[79]
Israel, Phys
W. Israel, Phys. Rev. Lett.57397 (1986)
1986
-
[80]
Some Properties of Noether Charge and a Proposal for Dynamical Black Hole Entropy
V. Iyer and R. M. Wald, Phys. Rev. D50846–64 (1994), [arXiv:gr-qc/9403028]
work page internal anchor Pith review Pith/arXiv arXiv 1994
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