pith. sign in

arxiv: 1906.11867 · v1 · pith:BRWOZETDnew · submitted 2019-06-27 · 🌌 astro-ph.HE · astro-ph.GA

The X-ray Coronae of two massive galaxies in the core of the Perseus cluster

N. Arakawa , A. C. Fabian , S. A. Walker This is my paper

Pith reviewed 2026-05-25 14:14 UTC · model grok-4.3

classification 🌌 astro-ph.HE astro-ph.GA
keywords minicoronaeX-ray coronaePerseus clusterelliptical galaxiesviscous strippingmagnetic suppressionChandra observationsintracluster medium
0
0 comments X

The pith

Two massive galaxies in the Perseus cluster core retain minicoronae of cool X-ray gas.

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

This paper studies the X-ray properties of NGC 1270 and NGC 1272 using Chandra data. It finds that each galaxy contains a minicorona with temperatures of 0.99 keV and 0.63 keV and radii of 1.4 kpc and 1.2 kpc. The analysis shows that viscous stripping would deplete the gas much faster than stellar mass loss can replenish it, suggesting magnetic fields suppress the processes. The galaxies must maintain equilibrium in their cooling, heating, and mass flows. A reader cares because these minicoronae illustrate how gas survives in dense cluster environments near supermassive black holes.

Core claim

With thermal emission from the minicorona dominating over any power-law radiation components, we find that both NGC 1270 and NGC 1272 encompass minicoronae, the temperature and radius of which are 0.99 keV and 0.63 keV; 1.4 kpc and 1.2 kpc respectively. For NGC 1272, the thermal coronal component dominates the core emission by a factor of over 10. We show that the depletion time scale of minicoronal gas via viscous stripping is shorter by a factor of 100 than the replenishment time scale due to stellar mass loss. Magnetic fields are presumably responsible for suppression of the transport processes. Finally, we show that both objects have to meet a balance between cooling and heating as well

What carries the argument

Minicorona: relatively cool soft X-ray emitting gas in the central region of massive early-type galaxies that has not been fully stripped by the intracluster medium or accreted by the central black hole.

If this is right

  • The thermal minicorona dominates the core emission in NGC 1272 by a factor exceeding 10.
  • Depletion of minicoronal gas by viscous stripping occurs on a timescale 100 times shorter than replenishment by stellar mass loss.
  • Magnetic fields suppress transport processes to allow the minicoronae to persist.
  • Both galaxies require a balance between cooling and heating.
  • Both galaxies require a balance among mass replenishment, stripping, and accretion.

Where Pith is reading between the lines

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

  • If magnetic suppression is general, minicoronae could be common in other cluster elliptical galaxies with strong magnetic fields.
  • The mass balance conditions may link directly to the accretion rates feeding the central supermassive black holes.
  • Multi-wavelength observations could confirm the role of magnetic fields by searching for signatures of suppressed transport.

Load-bearing premise

The calculation of depletion and replenishment timescales uses standard hydrodynamic viscous stripping and stellar mass-loss rates without initial magnetic effects, and attributes all soft X-ray emission to thermal minicorona gas.

What would settle it

Finding that the soft X-ray spectrum is dominated by non-thermal emission or that the observed gas depletion rate equals the replenishment rate without magnetic suppression would falsify the need for magnetic fields.

Figures

Figures reproduced from arXiv: 1906.11867 by A. C. Fabian, N. Arakawa, S. A. Walker.

Figure 1
Figure 1. Figure 1: 0.5 − 7.0 keV consolidated and exposure-corrected im￾age of Chandra observations of the Perseus cluster. NGC 1272 is marked with a circle while NGC 1270 is indicated with a square. are 11713, 11714, 11715, 11716, 12025, 12033, 12036 and 12037. A catalogue of the Perseus cluster galaxies given by Brunzendorf & Meusinger (1999) was used to identify these two X-ray sources. The coordinates of NGC 1270 and NGC… view at source ↗
Figure 2
Figure 2. Figure 2: X-ray spectral fitting. (Left Panel) X-ray spectrum of NGC 1270 in the Perseus cluster fitted with a galactic absorption applied to a power-law continuum and an apec thermal model. The addition of a power-law component slightly improved the fit. (Right Panel) X-ray spectrum of NGC 1272 fitted with a galactic absorption applied to an apec thermal model. with the inner part of the Gaussian function of σc for… view at source ↗
Figure 3
Figure 3. Figure 3: Images from the ACIS-I detector of Chandra in 0.5−2.0 keV, of NGC 1270 (left) and NGC 1272 (right). Note that the observations of these two galaxies are at high off-axis distances of 9.700 and 5.180 respectively. 3.4 The density and mass of minicoronae The normalization value A of an apec model is defined in CGS units as A ≡ 10−14 4π [DA(1 + z)]2 Z nenHdV, (2) where DA, z, ne and nH are the angular diamete… view at source ↗
Figure 4
Figure 4. Figure 4: Background-subtracted X-ray surface brightness profiles and PSF profiles of the two galaxies in the 0.5 to 2.0 keV energy band. Left: NGC 1270 profile. Right: NGC 1272 profile. Surface brightness profiles are indicated with 1 σ error bars. Profiles of the observation and the PSF for NGC 1272 and the PSF for NGC 1270 are fitted with a Gaussian function while the observation of NGC 1270 is fitted with a doub… view at source ↗
read the original abstract

We study the X-ray properties of two elliptical galaxies, NGC 1270 and NGC 1272, in the core of the Perseus cluster with deep Chandra observations. Both galaxies have central supermassive black holes, the mass of which is $6.0 \times 10^{9}$ M$_{\odot}$ and $2.0 \times 10^{9}$ M$_{\odot}$ respectively. Our aim is to examine relatively cool soft X-ray emitting gas within the central region of these massive early-type galaxies. Such gas, referred to as a Minicorona in previous studies is common in the core of large elliptical cluster galaxies. It has not been completely stripped or evaporated by the surrounding hot intracluster medium and nor fully accreted onto the central black hole. With thermal emission from the minicorona dominating over any power-law radiation components, we find that both NGC 1270 and NGC 1272 encompass minicoronae, the temperature and radius of which are $0.99$ keV and $0.63$ keV; $1.4$ kpc and $1.2$ kpc respectively. For NGC 1272, the thermal coronal component dominates the core emission by a factor of over 10. We show that the depletion time scale of minicoronal gas via viscous stripping is shorter by a factor of $100$ than the replenishment time scale due to stellar mass loss. Magnetic fields are presumably responsible for suppression of the transport processes. Finally, we show that both objects have to meet a balance between cooling and heating as well as that among mass replenishment, stripping and accretion.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 1 minor

Summary. The paper analyzes deep Chandra X-ray observations of NGC 1270 and NGC 1272 in the Perseus cluster core. It identifies minicoronae with fitted temperatures of 0.99 keV (NGC 1270) and 0.63 keV (NGC 1272) and radii of 1.4 kpc and 1.2 kpc. For NGC 1272 the thermal component is reported to dominate core emission by a factor >10. The work computes a factor-of-100 ratio between viscous-stripping depletion and stellar-mass-loss replenishment timescales, invokes magnetic suppression to reconcile the discrepancy, and concludes that both galaxies must satisfy cooling-heating and mass (replenishment-stripping-accretion) balance.

Significance. If the reported temperatures, radii, emission-component dominance, and timescale ratio are robustly supported by the data and modeling, the result would strengthen the case that minicoronae persist in cluster ellipticals and that magnetic fields are required to suppress hydrodynamic transport at these scales. The explicit mass-balance and cooling-heating arguments would also provide a concrete observational anchor for models of galaxy-ICM interaction and AGN fueling.

major comments (3)
  1. [time-scale comparison section] The time-scale comparison (abstract and the section deriving the factor-of-100 ratio) relies on standard hydrodynamic viscous-stripping and stellar mass-loss formulae applied to the fitted T and r values together with assumed ICM density and viscosity. No explicit equations, numerical inputs (e.g., viscosity coefficient, ICM density at the galaxy location), or step-by-step derivation are provided, making it impossible to verify that the ratio is indeed ~100 or that the hydrodynamic formulae remain applicable at ~1 kpc scales before magnetic suppression is invoked.
  2. [spectral analysis section] Spectral modeling and background treatment are not described. The reported temperatures, radii, and the factor-of-10 dominance for NGC 1272 require details on the plasma model (e.g., APEC parameters, abundance), the extraction regions, background subtraction method, and how the minicorona radius was determined from the surface-brightness profile or spectral decomposition. Without these, the attribution of all soft X-ray core emission to thermal minicorona gas cannot be assessed.
  3. [discussion of balances] The final balance arguments (cooling-heating and mass replenishment-stripping-accretion) rest directly on the timescale ratio and the pure-thermal attribution. If either the hydrodynamic rate formulae or the emission decomposition require revision, these balance conclusions lose their quantitative foundation.
minor comments (1)
  1. [abstract] The abstract states the black-hole masses but does not indicate whether they are used in any calculation; if they are not required for the minicorona analysis, their inclusion should be justified or moved to the introduction.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the careful and constructive review. The comments highlight areas where additional methodological detail will strengthen the paper. We address each major comment below and have prepared revisions to incorporate the requested information.

read point-by-point responses

  1. Referee: [time-scale comparison section] The time-scale comparison (abstract and the section deriving the factor-of-100 ratio) relies on standard hydrodynamic viscous-stripping and stellar mass-loss formulae applied to the fitted T and r values together with assumed ICM density and viscosity. No explicit equations, numerical inputs (e.g., viscosity coefficient, ICM density at the galaxy location), or step-by-step derivation are provided, making it impossible to verify that the ratio is indeed ~100 or that the hydrodynamic formulae remain applicable at ~1 kpc scales before magnetic suppression is invoked.

    Authors: We agree that the time-scale section requires explicit equations and inputs for reproducibility. In the revised manuscript we add the precise viscous-stripping timescale formula (the standard hydrodynamic expression from Nulsen 1982 and subsequent works), the stellar mass-loss rate formula, the adopted ICM density at the projected locations of NGC 1270 and NGC 1272, the viscosity coefficient, and the step-by-step numerical evaluation that produces the factor-of-100 ratio. We also include a short paragraph discussing the regime of applicability of the hydrodynamic formulae at ~1 kpc prior to invoking magnetic suppression. revision: yes

  2. Referee: [spectral analysis section] Spectral modeling and background treatment are not described. The reported temperatures, radii, and the factor-of-10 dominance for NGC 1272 require details on the plasma model (e.g., APEC parameters, abundance), the extraction regions, background subtraction method, and how the minicorona radius was determined from the surface-brightness profile or spectral decomposition. Without these, the attribution of all soft X-ray core emission to thermal minicorona gas cannot be assessed.

    Authors: We acknowledge that the original text omitted a dedicated description of the spectral analysis. The revised manuscript adds a new subsection that specifies: the APEC plasma model with solar abundances, the circular extraction apertures used for the core spectra, the background subtraction procedure (local annulus or blank-sky fields), the fitting statistics, and the operational definition of the minicorona radii (intersection of the surface-brightness profile with the extrapolated ICM level, cross-checked by spectral decomposition). These additions confirm that the thermal component dominates the core emission of NGC 1272 by more than a factor of 10. revision: yes

  3. Referee: [discussion of balances] The final balance arguments (cooling-heating and mass replenishment-stripping-accretion) rest directly on the timescale ratio and the pure-thermal attribution. If either the hydrodynamic rate formulae or the emission decomposition require revision, these balance conclusions lose their quantitative foundation.

    Authors: The balance conclusions are indeed predicated on the robustness of the timescale ratio and the spectral decomposition. With the explicit derivations and modeling details now provided in the revised sections, the quantitative foundation of the cooling-heating and mass-balance arguments is verifiable from the data. The conclusions themselves are unchanged. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivations use external standard formulas on fitted observables

full rationale

The paper's central results are direct spectral fits yielding T=0.99 keV, r=1.4 kpc (NGC 1270) and T=0.63 keV, r=1.2 kpc (NGC 1272), plus the statement that thermal emission dominates by >10 for NGC 1272. The factor-of-100 timescale discrepancy is obtained by inserting these values into standard hydrodynamic viscous-stripping and stellar-mass-loss rate expressions taken from the literature; the discrepancy is then interpreted as evidence for magnetic suppression. This is a conventional calculation, not a reduction of any claimed prediction to the fitted parameters by construction. No self-citation chains, ansatzes smuggled via prior work, or uniqueness theorems are invoked to force the conclusions. The derivation chain remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

The analysis rests on standard X-ray plasma emission models and hydrodynamic time-scale expressions common in the field; no new entities are postulated.

free parameters (1)
  • Minicorona temperature and radius = 0.99 keV and 1.4 kpc for NGC 1270; 0.63 keV and 1.2 kpc for NGC 1272
    Obtained from spectral fitting of Chandra data for each galaxy.
axioms (2)
  • domain assumption Soft X-ray emission is thermal from optically thin plasma
    Invoked to interpret the minicorona spectra.
  • standard math Standard hydrodynamic expressions for viscous stripping and stellar mass loss
    Used to compute depletion and replenishment time scales.

pith-pipeline@v0.9.0 · 5852 in / 1498 out tokens · 53075 ms · 2026-05-25T14:14:19.385499+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

32 extracted references · 32 canonical work pages · 2 internal anchors

  1. [1]

    Bondi H., 1952, @doi [ ] 10.1093/mnras/112.2.195 , http://ads.nao.ac.jp/abs/1952MNRAS.112..195B 112, 195

    work page doi:10.1093/mnras/112.2.195 1952

  2. [2]

    Brunzendorf J., Meusinger H., 1999, @doi [ ] 10.1051/aas:1999111 , http://ads.nao.ac.jp/abs/1999A 139, 141

    work page doi:10.1051/aas:1999111 1999

  3. [3]

    Churazov E., Forman W., Jones C., B \"o hringer H., 2003, @doi [ ] 10.1086/374923 , https://ui.adsabs.harvard.edu/\#abs/2003ApJ...590..225C 590, 225

    work page doi:10.1086/374923 2003

  4. [4]

    P., 2007, @doi [ ] 10.1086/519833 , https://ui.adsabs.harvard.edu/abs/2007ApJ...665.1038C 665, 1038

    Ciotti L., Ostriker J. P., 2007, @doi [ ] 10.1086/519833 , https://ui.adsabs.harvard.edu/abs/2007ApJ...665.1038C 665, 1038

    work page doi:10.1086/519833 2007

  5. [5]

    L., Songaila A., 1977, @doi [ ] 10.1038/266501a0 , http://adsabs.harvard.edu/abs/1977Natur.266..501C 266, 501

    Cowie L. L., Songaila A., 1977, @doi [ ] 10.1038/266501a0 , http://adsabs.harvard.edu/abs/1977Natur.266..501C 266, 501

    work page doi:10.1038/266501a0 1977

  6. [6]

    C., Canizares C

    Fabian A. C., Canizares C. R., 1988, @doi [ ] 10.1038/333829a0 , http://ads.nao.ac.jp/abs/1988Natur.333..829F 333, 829

    work page doi:10.1038/333829a0 1988

  7. [7]

    C., Rees M

    Fabian A. C., Rees M. J., 1995, @doi [ ] 10.1093/mnras/277.1.L55 , http://ads.nao.ac.jp/abs/1995MNRAS.277L..55F 277, L55

    work page doi:10.1093/mnras/277.1.l55 1995

  8. [8]

    A., et al., 2011, @doi [ ] 10.1111/j.1365-2966.2011.18706.x , http://adsabs.harvard.edu/abs/2011MNRAS.417.1621D 417, 1621

    Fabian A. C., et al., 2011, @doi [ ] 10.1111/j.1365-2966.2011.19402.x , http://ads.nao.ac.jp/abs/2011MNRAS.418.2154F 418, 2154

    work page doi:10.1111/j.1365-2966.2011.19402.x 2011

  9. [9]

    C., Sanders J

    Fabian A. C., Sanders J. S., Haehnelt M., Rees M. J., Miller J. M., 2013, @doi [ ] 10.1093/mnrasl/slt004 , https://ui.adsabs.harvard.edu/#abs/2013MNRAS.431L..38F 431, L38

    work page doi:10.1093/mnrasl/slt004 2013

  10. [10]

    Kalberla P. M. W., Burton W. B., Hartmann D., Arnal E. M., Bajaja E., Morras R., P \"o ppel W. G. L., 2005, @doi [ ] 10.1051/0004-6361:20041864 , http://ads.nao.ac.jp/abs/2005A

    work page doi:10.1051/0004-6361:20041864 2005

  11. [11]

    C., 2013, @doi [ ] 10.1146/annurev-astro-082708-101811 , http://adsabs.harvard.edu/abs/2013ARA

    Kormendy J., Ho L. C., 2013, @doi [ ] 10.1146/annurev-astro-082708-101811 , http://adsabs.harvard.edu/abs/2013ARA

    work page internal anchor Pith review doi:10.1146/annurev-astro-082708-101811 2013

  12. [12]

    McBride J., McCourt M., 2014, @doi [ ] 10.1093/mnras/stu945 , https://ui.adsabs.harvard.edu/#abs/2014MNRAS.442..838M 442, 838

    work page doi:10.1093/mnras/stu945 2014

  13. [13]

    A., 1994, @doi [ ] 10.1093/mnras/268.2.405 , https://ui.adsabs.harvard.edu/abs/1994MNRAS.268..405N 268, 405

    Nandra K., Pounds K. A., 1994, @doi [ ] 10.1093/mnras/268.2.405 , https://ui.adsabs.harvard.edu/abs/1994MNRAS.268..405N 268, 405

    work page doi:10.1093/mnras/268.2.405 1994

  14. [14]

    Narayan R., Yi I., 1995, @doi [ ] 10.1086/176343 , http://ads.nao.ac.jp/abs/1995ApJ...452..710N 452, 710

    work page doi:10.1086/176343 1995

  15. [15]

    Nulsen P. E. J., 1982, @doi [ ] 10.1093/mnras/198.4.1007 , https://ui.adsabs.harvard.edu/\#abs/1982MNRAS.198.1007N 198, 1007

    work page doi:10.1093/mnras/198.4.1007 1982

  16. [16]

    Pellegrini S., 2005, @doi [ ] 10.1086/429267 , http://ads.nao.ac.jp/abs/2005ApJ...624..155P 624, 155

    work page doi:10.1086/429267 2005

  17. [17]

    R., Fabian A

    Russell H. R., Fabian A. C., McNamara B. R., Miller J. M., Nulsen P. E. J., Piotrowska J. M., Reynolds C. S., 2018, @doi [ ] 10.1093/mnras/sty835 , http://adsabs.harvard.edu/abs/2018MNRAS.477.3583R 477, 3583

    work page doi:10.1093/mnras/sty835 2018

  18. [18]

    S., Fabian A

    Sanders J. S., Fabian A. C., Sun M., Churazov E., Simionescu A., Walker S. A., Werner N., 2014, @doi [ ] 10.1093/mnras/stu092 , http://ads.nao.ac.jp/abs/2014MNRAS.439.1182S 439, 1182

    work page doi:10.1093/mnras/stu092 2014

  19. [19]

    Mignone and Jonathan C

    Santra S., Sanders J. S., Fabian A. C., 2007, @doi [ ] 10.1111/j.1365-2966.2007.12437.x , http://ads.nao.ac.jp/abs/2007MNRAS.382..895S 382, 895

    work page doi:10.1111/j.1365-2966.2007.12437.x 2007

  20. [20]

    L., 1986, @doi [Reviews of Modern Physics] 10.1103/RevModPhys.58.1 , https://ui.adsabs.harvard.edu/abs/1986RvMP...58....1S 58, 1

    Sarazin C. L., 1986, @doi [Reviews of Modern Physics] 10.1103/RevModPhys.58.1 , https://ui.adsabs.harvard.edu/abs/1986RvMP...58....1S 58, 1

    work page doi:10.1103/revmodphys.58.1 1986

  21. [21]

    W., Baldi A., Elvis M., Jerjen H., Pellegrini S., Siemiginowska A., 2006, @doi [ ] 10.1086/499934 , http://ads.nao.ac.jp/abs/2006ApJ...640..126S 640, 126

    Soria R., Fabbiano G., Graham A. W., Baldi A., Elvis M., Jerjen H., Pellegrini S., Siemiginowska A., 2006, @doi [ ] 10.1086/499934 , http://ads.nao.ac.jp/abs/2006ApJ...640..126S 640, 126

    work page doi:10.1086/499934 2006

  22. [22]

    Spitzer L., 1962, Physics of Fully Ionized Gases

    work page 1962

  23. [23]

    S., 2005, @doi [ ] 10.1086/425298 , http://adsabs.harvard.edu/abs/2005ApJ...619..169S 619, 169

    Sun M., Vikhlinin A., Forman W., Jones C., Murray S. S., 2005, @doi [ ] 10.1086/425298 , http://adsabs.harvard.edu/abs/2005ApJ...619..169S 619, 169

    work page doi:10.1086/425298 2005

  24. [24]

    Sun M., Jones C., Forman W., Vikhlinin A., Donahue M., Voit M., 2007, @doi [ ] 10.1086/510895 , http://ads.nao.ac.jp/abs/2007ApJ...657..197S 657, 197

    work page doi:10.1086/510895 2007

  25. [25]

    T., Ogilvie G

    Vasudevan R. V., Fabian A. C., 2009, @doi [ ] 10.1111/j.1365-2966.2008.14108.x , http://adsabs.harvard.edu/abs/2009MNRAS.392.1124V 392, 1124

    work page doi:10.1111/j.1365-2966.2008.14108.x 2009

  26. [26]

    Vikhlinin A., Markevitch M., Forman W., Jones C., 2001, @doi [ ] 10.1086/323181 , http://adsabs.harvard.edu/abs/2001ApJ...555L..87V 555, L87

    work page doi:10.1086/323181 2001

  27. [27]

    A., Yukita M., Million E

    Wong K.-W., Irwin J. A., Yukita M., Million E. T., Mathews W. G., Bregman J. N., 2011, @doi [ ] 10.1088/2041-8205/736/1/L23 , http://adsabs.harvard.edu/abs/2011ApJ...736L..23W 736, L23

    work page doi:10.1088/2041-8205/736/1/l23 2011

  28. [28]

    A., Shcherbakov R

    Wong K.-W., Irwin J. A., Shcherbakov R. V., Yukita M., Million E. T., Bregman J. N., 2014, @doi [ ] 10.1088/0004-637X/780/1/9 , http://adsabs.harvard.edu/abs/2014ApJ...780....9W 780, 9

    work page doi:10.1088/0004-637x/780/1/9 2014

  29. [29]

    Y., Ohashi T., Furusho T., 2002, @doi [ ] 10.1086/342652 , http://adsabs.harvard.edu/abs/2002ApJ...578..833Y 578, 833

    Yamasaki N. Y., Ohashi T., Furusho T., 2002, @doi [ ] 10.1086/342652 , http://adsabs.harvard.edu/abs/2002ApJ...578..833Y 578, 833

    work page doi:10.1086/342652 2002

  30. [30]

    Yuan F., Narayan R., 2014, @doi [ ] 10.1146/annurev-astro-082812-141003 , http://adsabs.harvard.edu/abs/2014ARA

    work page internal anchor Pith review doi:10.1146/annurev-astro-082812-141003 2014

  31. [31]

    van den Bosch R. C. E., Gebhardt K., G \"u ltekin K., van de Ven G., van der Wel A., Walsh J. L., 2012, @doi [ ] 10.1038/nature11592 , http://adsabs.harvard.edu/abs/2012Natur.491..729V 491, 729

    work page doi:10.1038/nature11592 2012

  32. [32]

    write newline

    " write newline "" before.all 'output.state := FUNCTION fin.entry write newline FUNCTION new.block output.state before.all = 'skip after.block 'output.state := if FUNCTION new.sentence output.state after.block = 'skip output.state before.all = 'skip after.sentence 'output.state := if if FUNCTION not #0 #1 if FUNCTION and 'skip pop #0 if FUNCTION or pop #1...

    work page