{ "schema": "story-copy/2", "meta": { "owner": "U_copy", "about": "Every word the v2 story shows: per-beat kinetic lines (display, display_short, sub, sub_short), screen-reader narrative, Physics layer, HUD and dock labels, plaque, shell chips, film captions, the honest-simplification list and credits. Numbers appear only as {{key}} templates; tests/js/story_copy_lint.mjs enforces it.", "templates": "{{name}} reads story-data keys (flat key, then dotted path into keys, then dotted path into the story JSON root). {{$name}} is a live FrameState/UI value listed in `live`. Names listed in `derive` are computed from keys by the stated rule. A line with `when: flag` shows only when the data flag is true; otherwise its `else` block (or nothing, when `else` is null).", "emphasis": "*text* marks the italic (Newsreader) part of a kinetic line.", "beat_entry": "copy[beatId] = {display, display_short, sub, sub_short, narrative, physics, then?, chip?, hint?}. display/sub of the entry are the beat's first kinetic line (frozen interface, DESIGN_final 5.11); `then` lists the later lines of the same beat in order, each with its own id and u window within the beat. Text ids for FrameState.text are `.0` (the entry) and `.` for then[k-1].", "limits": "display <= 8 words, display_short <= 5, sub <= 25, sub_short <= 12; a {{template}} counts as one word, a digit group as one word.", "conditions": "A line's `when` flag hides it (or swaps in its `else` block; `else: null` hides it). An `extra` block {when, sub, narrative} is appended to its line's sub and narrative when its flag is true; the word limits apply to the joined text. The beat's screen-reader text is the entry narrative (or else.narrative) followed by the narratives of its visible `then` lines and extras. A beat whose entry and every line are hidden is skipped by the timeline (B7e without has_cold_knot). A `then` line whose display and sub are both null shows nothing in the bands; it only adds its physics and narrative (B13.4, B14.1 sub-only line in the band)." }, "beats_order": [ "B0", "B1", "B2", "B3", "B4", "B5", "B6", "B7a", "B7b", "B7c", "B7d", "B7e", "B8", "B9", "B10", "B11", "B12a", "B12b", "B13", "B14" ], "B0": { "chip": "How a spectrum is made", "display": "How a spectrum is made", "display_short": "How a spectrum is made", "sub": "Follow one beam of quasar light through the gas around galaxy {{galaxy}}.", "sub_short": "Follow one beam of quasar light.", "narrative": "How a spectrum is made. You will follow one beam of quasar light through the gas around galaxy {{galaxy}}, and watch its spectrum build up cell by cell. Hold Space or the hold button to start, or choose Watch.", "physics": null }, "B1": { "chip": "Light", "display": "This light left a quasar long ago.", "display_short": "Light from a distant quasar.", "sub": "The strip below is this quasar's light, as a perfect telescope travelling with it would record it. For now, all of it gets through.", "sub_short": "For now, all the light gets through.", "narrative": "A quasar far behind the galaxy sends its light toward us. The spectrum below is what a perfect telescope travelling with the light would record. So far nothing is taken: all the light gets through.", "physics": "The spectrum shows the fraction of light left at each speed along the beam. It is the light that has crossed every cell behind the packet, before any telescope blur.", "then": [ { "id": "B1.1", "u": [ 0.5, 1.0 ], "display": "Something stood in its way.", "display_short": "Something stood in its way.", "sub": null, "sub_short": null, "narrative": null } ] }, "B2": { "chip": "The halo", "act_title": true, "display": "Galaxies sit inside gas *too faint to see.*", "display_short": "Gas *too faint to see.*", "sub": "The gas shows itself only by the light it takes from things behind it. These colours are our choice, not its light.", "sub_short": "It shows only by the light it takes.", "narrative": "From outside, galaxy {{galaxy}} sits in a halo of thin gas reaching {{R200c}} kpc from its centre. The gas is too faint to see directly; it shows itself by the light it takes from things behind it. The colours drawn here are our choice, not light the gas gives off.", "physics": "Galaxy {{galaxy}}, TNG50-1 at z = 0, {{mw_compare}}. R200c = {{R200c}} kpc, M200c = {{M200c}} M☉. The beam passes {{b_kpc}} kpc from the centre; the path from −R200c to +R200c is {{length_kpc}} kpc. Only gas within R200c is counted; real light also crosses gas beyond it, including our own Galaxy's.", "hint": "Drag to turn the halo.", "then": [ { "id": "B2.1", "u": [ 0.55, 1.0 ], "display": "We follow this one beam through it.", "display_short": "We follow this beam.", "sub": "Every beam meets different gas, so every spectrum differs. Pick another beam at any time.", "sub_short": "Every beam meets different gas.", "narrative": null } ] }, "B3": { "chip": "The halo", "display": "Every cell has a density, heat and speed.", "display_short": "Each cell: density, heat, speed.", "sub": "The beam touches hundreds of gas cells. Each one lights up as the light reaches it.", "sub_short": "Each cell lights up as the light arrives.", "narrative": "We drop onto the beam at the edge of the halo. The beam touches hundreds of gas cells; each lights up as the light reaches it, and its density, heat and speed float beside it. These outskirts are thin, so almost nothing is taken.", "physics": "{{n_kernels}} smoothing kernels touch the beam; about {{n_crossed}} cells are actually crossed. The path inside a kernel has median {{dl_median_kpc}} kpc and maximum {{dl_max_kpc}} kpc. n_H = X_H ρ / m_H, with X_H between {{XH_min}} and {{XH_max}}.", "hint": "Click a bead to pin its numbers.", "then": [ { "id": "B3.1", "u": [ 0.55, 1.0 ], "display": "So far, almost nothing is taken.", "display_short": "Almost nothing taken yet.", "sub": "By now O VI has taken {{b3_ovi_depth}} % of the light at its deepest colour.", "sub_short": "O VI has taken {{b3_ovi_depth}} % so far.", "narrative": null } ] }, "B4": { "chip": "The halo", "when": "has_first_ovi", "display": "Each cell leaves a *shadow.*", "display_short": "Each cell leaves a *shadow.*", "sub": "Atoms take a sliver of one colour out of the light: the first cell's dip was {{b4_first_depth}} % deep. The rest goes on.", "sub_short": "Atoms take a sliver of one colour.", "narrative": "The first warm-hot cells light up on the beam, and the O VI row of the spectrum gets its first dip, {{b4_first_depth}} % deep. Atoms take a sliver of one colour out of the light; the rest of the light goes on.", "physics": "Shadow, not glow: absorption makes a dark notch, not a bright one. τ₀ ∝ N f λ / b, and the dip's shape is τ(v) = τ₀ H(a, x), a Voigt profile whose core is a Gaussian in speed.", "else": { "display": "This beam is almost clear in O VI.", "display_short": "Almost clear in O VI.", "sub": "So the next steps use a made-up cell, marked as an example, to show how one cell leaves a shadow.", "sub_short": "The next cell is a marked example.", "narrative": "This beam is almost clear in O VI, so the next steps use a made-up cell, marked as an example, to show how one cell leaves a shadow." } }, "B5": { "chip": "Cloud A", "act_title": true, "when": "hi_black", "display": "A cool clump.", "display_short": "A cool clump.", "sub": null, "sub_short": null, "narrative": "The light enters cloud A, a cool clump of gas. In the cell holding most of its neutral hydrogen, one hydrogen atom in {{cloudA_xHI_one_in}} keeps its electron, against one in {{hot_xHI_one_in}} in warm-hot gas.", "physics": "n(H I) = x_HI n_H, with x_HI from the simulation's own recipe; x_HI = {{cloudA_xHI}} in cloud A's core cell, the one holding most of its H I column (denser cells exist, and the cloud's cells range much lower). The equation uses the core cell: T = {{cloudA_core_T}} K gives b = {{cloudA_core_bH}} km/s for hydrogen and {{cloudA_core_bO}} km/s for oxygen, which is heavier. Black already: more hydrogen from here on cannot make it darker, only wider.", "hint": "Drag the surface level: the cloud changes, the spectrum does not.", "then": [ { "id": "B5.1", "u": [ 0.2, 0.6 ], "display": "*One hydrogen atom in {{cloudA_xHI_one_in}} keeps its electron.*", "display_short": "*One in {{cloudA_xHI_one_in}} stays neutral.*", "sub": "That is at its core. In warm-hot gas only one in {{hot_xHI_one_in}} does: about {{xHI_ratio_shown}} times fewer. Neutral hydrogen takes the colour we follow.", "sub_short": "Neutral hydrogen takes the colour we follow." }, { "id": "B5.2", "u": [ 0.6, 1.0 ], "display": "One clump, and the dip is black.", "display_short": "One clump, a black dip.", "sub": "Hydrogen's dip goes black within a few cells.", "sub_short": "Black within a few cells.", "extra": { "when": "has_ovi_skin", "sub": "Its warm-hot skin comes next: O VI loses another {{b5_ovi_drop}} % of its light.", "narrative": "The clump's warm-hot skin comes next: by the end of this stretch O VI loses another {{b5_ovi_drop}} % of its light, at {{b5_ovi_V}} km/s." }, "narrative": "Within a few cells the hydrogen dip goes black." } ], "else": { "display": "Here even hydrogen stays grey.", "display_short": "Hydrogen stays grey.", "sub": "Little cool gas lies on this beam, so no dip turns black.", "sub_short": "Little cool gas on this beam.", "narrative": "Here even hydrogen stays grey: little cool gas lies on this beam, so no dip turns black." } }, "B6": { "chip": "The quiet", "when": "has_hot_stretch", "display": "Here the gas is *too hot to see.*", "display_short": "*Too hot to see.*", "sub": "So hot that oxygen loses even a sixth electron and hydrogen keeps almost none. O VI and H I take almost no light here.", "sub_short": "Too hot for much O VI or H I.", "narrative": "A long stretch of very hot gas follows. Oxygen loses even a sixth electron here, and hydrogen keeps almost none, so O VI and H I take almost no light: the spectrum barely changes. The gas is still there; it would show in X-rays.", "physics": "The gas is still there: at these temperatures oxygen is mostly O VII and beyond, seen only in X-rays. Speeds are measured from the galaxy: we subtract its own motion, v_gal = {{v_gal}} km/s, so zero speed is the galaxy's. The slow expansion of space across the halo (up to {{hubble_kms}} km/s here) is not added.", "hint": "Flip the axis between wavelength and speed.", "else": null, "then": [ { "id": "B6.1", "u": [ 0.5, 1.0 ], "display": "Where a dip sits *means speed.*", "display_short": "A dip's place means speed.", "sub": "Moving toward us shifts a shadow bluer, like a siren. Cloud A's dip sits left for its speed, not its order.", "sub_short": "Toward us shifts bluer, like a siren.", "narrative": "Where a dip sits means speed: gas moving toward us shifts its shadow bluer, like a siren. Cloud A's dip sits on the left because of its speed, not because it came first." } ] }, "B7a": { "chip": "Cloud B", "act_title": true, "display": "Cloud B", "display_short": "Cloud B", "sub": null, "sub_short": null, "narrative": "The camera slows as the light reaches cloud B, a long warm-hot structure. The O VI dip deepens.", "physics": null }, "B7b": { "chip": "Cloud B", "when": "ovi_strong", "display": "Amount sets how much light is taken.", "display_short": "Amount sets the bite.", "sub": "This one cell holds {{c263_ovi_share_words}} of all the O VI on the beam. Its dip grows term by term: amount, width, place.", "sub_short": "One cell holds {{c263_ovi_share_words}} of the O VI.", "narrative": "We stop inside cell {{s5_cell}}, which holds {{c263_ovi_share_words}} of all the O VI on the beam. Its dip is drawn term by term: the amount sets its area, the heat sets its width, the speed sets its place. At the centre {{c263_Fc}} % of the light gets through.", "physics": "Cell {{s5_cell}}: log N = {{c263_logN}}, b = {{c263_b}} km/s, f = {{ovi_f}}, λ = {{ovi_lam}} Å, so τ₀ = {{c263_tau0}} and {{c263_Fc}} % of the light gets through at the centre. Widths come from heat only, with no turbulence, so each cell's dip is as narrow as it can be. Hydrogen at that T would have b = {{c263_bH}} km/s, {{s5_bH_ratio}} times wider.", "hint": "Hover a term to find it in the dip.", "then": [ { "id": "B7b.1", "u": [ 0.5, 1.0 ], "display": "*Heat spreads it out.*", "display_short": "*Heat spreads it out.*", "sub": "Hotter ions jiggle faster, so the same amount spreads over more speeds: wider and shallower.", "sub_short": "Hotter means wider and shallower.", "narrative": null } ], "else": { "display": "One cell, one small dip.", "display_short": "One cell, one dip.", "sub": "O VI is faint on this beam; the strongest cell still shows how amount, heat and speed shape a dip.", "sub_short": "Amount, heat and speed shape it.", "narrative": "O VI is faint on this beam. We stop at its strongest cell, cell {{s5_cell}}, to see how amount, heat and speed shape one dip." } }, "B7c": { "chip": "Cloud B", "display": "Change the heat, watch the dip.", "display_short": "Drag the heat.", "sub": "Warmer gas spreads the dip wider. But O VI lives only in a band of heat: outside it, the dip fades.", "sub_short": "O VI lives in a band of heat.", "narrative": "Drag the temperature of cell {{s5_cell}}. Warmer gas spreads its dip wider. Above {{ovi_T_hot_fade}} K or below {{ovi_T_cool_fade}} K the share of oxygen in the O VI state falls below half its peak, and the dip fades.", "physics": "Density and metal content are held fixed; real gas would also change density. The O VI share is read from the ionisation table at this cell's density. Equal area holds only while τ₀ is small; past that, saturation begins.", "hint": "Drag the T term.", "states": { "hot": { "when_live": "$T > ovi_T_hot_fade", "display": "Too hot: oxygen loses another electron.", "display_short": "Too hot: dip fades.", "sub": "Above {{ovi_T_hot_fade}} K the O VI share here falls below half its peak, and the dip fades.", "sub_short": "Above {{ovi_T_hot_fade}} K the dip fades." }, "cool": { "when_live": "$T < ovi_T_cool_fade", "display": "Too cool: oxygen keeps more electrons.", "display_short": "Too cool: dip fades.", "sub": "Below {{ovi_T_cool_fade}} K the O VI share here falls below half its peak, and the dip fades.", "sub_short": "Below {{ovi_T_cool_fade}} K the dip fades." } } }, "B7d": { "chip": "Cloud B", "display": "One cloud, many speeds, a wide dip.", "display_short": "Many speeds, one wide dip.", "sub": "Each cell adds its own shadow at its own speed. The shadows stack: each passes a share of the light left.", "sub_short": "Shadows stack; each passes a share of what is left.", "narrative": "The rest of cloud B adds cells, each at its own speed. Their shadows stack into one broad, ragged O VI trough: each passes a share of the light left.", "physics": "τ_total = Σ τ_i and F = e^(−τ_total): τ adds, light multiplies. Single cells have b = {{ovi_b_min}} to {{ovi_b_max}} km/s; it is their different speeds that spread the trough.", "hint": "Brush a dip to light the cells that made it." }, "B7e": { "chip": "Cool cloud", "when": "has_cold_knot", "display": "Same place, *different gas.*", "display_short": "Same place, other gas.", "sub": "A second cool cloud hides in the black H I dip: about {{b7e_hi_v}} km/s at its densest. O VI beside it: {{b7e_ovi_v}} km/s.", "sub_short": "A second cool cloud, hidden in black.", "narrative": "At the far end of cloud B sits a second cool cloud. Its hydrogen, moving at about {{b7e_hi_v}} km/s where it is densest, is hidden inside the black hydrogen dip. The warm-hot O VI beside it moves at {{b7e_ovi_v}} km/s.", "physics": "Each speed is the peak of that cloud's own optical depth (its cells alone), not a dip in the full spectrum: the H I trough is black across all of these speeds, so on its own the spectrum cannot place this cloud. Neighbouring phases can move differently; ions in one dip need not share a cloud.", "else": null }, "B8": { "chip": "Halfway", "display": "Halfway. The galaxy sits beside us.", "display_short": "Halfway; galaxy beside us.", "sub": "Its centre is {{b_ly}} light-years to the side.", "extra": { "when": "richest_not_closest", "sub": "Closest does not mean most gas: {{ovi_frac_half}} % of the O VI is already behind us.", "narrative": "Being closest does not mean the most gas: {{ovi_frac_half}} % of the O VI and {{hi_frac_half}} % of the hydrogen are already behind us." }, "sub_short": "Its centre: {{b_ly}} light-years to the side.", "narrative": "Halfway along the beam the galaxy swings into view. Its centre is {{b_ly}} light-years to the side, the closest the beam comes.", "physics": "The midpoint of the path is the closest approach, b = {{b_kpc}} kpc. By here {{ovi_frac_half}} % of the O VI and {{hi_frac_half}} % of the H I have been collected.", "hint": "Drag to look around." }, "B9": { "chip": "Cloud C", "act_title": true, "when": "has_b9_new_dips", "display": "Past halfway, *new dips* still appear.", "display_short": "*New dips* still appear.", "sub": "New O VI dips appear at {{b9_new_minima}} km/s. The order of dips is not the order of clouds.", "sub_short": "Dip order is not cloud order.", "narrative": "Past halfway, new O VI dips appear at {{b9_new_minima}} km/s. The order of dips in the spectrum is not the order of clouds on the beam.", "physics": "O VI traces a medium; at a higher density level it breaks into pieces. Every O VI cloud shown here exists only above the level we chose.", "else": { "display": "Past halfway, *the light goes on.*", "display_short": "*The light goes on.*", "sub": "No new O VI dip appears in this stretch.", "sub_short": "No new O VI dip here.", "narrative": "Past halfway, the light goes on, and no new O VI dip appears in this stretch of the beam.", "physics": "O VI traces a medium; at a higher density level it breaks into pieces. Every O VI cloud shown here exists only above the level we chose." }, "then": [ { "id": "B9.1", "u": [ 0.4, 0.8 ], "when": "has_pair", "display": "Far apart, same speed, *same dip.*", "display_short": "Far apart, *same dip.*", "sub": "Gas {{pair_sep}} kpc apart moves at almost the same speed, so the spectrum cannot tell them apart: the clearest of {{n_pairs}} such pairs.", "sub_short": "{{pair_sep}} kpc apart, one dip.", "narrative": "Cell {{s6_cell_b}} drops its shadow into a dip that cell {{s6_cell_a}} made {{pair_sep}} kpc behind us: they move at almost the same speed, so the spectrum cannot tell them apart. This is the clearest of {{n_pairs}} such pairs on the beam.", "physics": "Cells {{s6_cell_a}} (ℓ = {{pair_a_l}} kpc) and {{s6_cell_b}} (ℓ = {{pair_b_l}} kpc) differ in speed by less than either dip's width.", "else": null }, { "id": "B9.2", "u": [ 0.8, 1.0 ], "display": "The spectrum keeps speed and loses place.", "display_short": "Speed kept, place lost.", "sub": "A dip records how fast gas moves along the beam, not where it sits.", "sub_short": "Speed, not place.", "narrative": "The spectrum keeps speed and loses place." } ] }, "B10": { "chip": "Cloud D", "display": "More gas, deeper dip.", "display_short": "More gas, deeper dip.", "sub": "More atoms darken a dip's centre while its width hardly changes, until the centre is black.", "sub_short": "More atoms, darker centre.", "narrative": "Cloud D is another cool clump. More atoms darken a dip's centre while its width hardly changes, until the centre is black.", "physics": "τ₀ grows in proportion to N; the centre lets through e^(−τ₀). H I total log N = {{hi_logN}} ({{hi_lls}}), peak τ = {{hi_peaktau}}. Near the top of the slider the widening comes from the damping wings, not the core. On this beam the fits land {{hi_fit_dlo}} to {{hi_fit_dhi}} dex from the true amount: a black dip gives only a rough amount, and a fit can err either way.", "hint": "Drag N on the ghost dip.", "then": [ { "id": "B10.1", "u": [ 0.45, 1.0 ], "when": "hi_black", "display": "Once black, *only wider.*", "display_short": "Once black, *only wider.*", "sub": "Cloud D's hydrogen lands on a dip that is already black: the trough widens, but cannot get darker.", "sub_short": "Black dips can only widen.", "else": null, "narrative": "But cloud D's hydrogen lands on a dip that is already black: the trough widens and cannot get darker." } ] }, "B11": { "chip": "Looking back", "act_title": true, "display": "This is everything *the light carried out.*", "display_short": "All the light carried out.", "sub": "{{ovi_n_visible}} cells left a visible O VI shadow. Their shadows merged into a few broad dips.", "sub_short": "{{ovi_n_visible}} shadows, a few dips.", "narrative": "Leaving the halo, the camera turns to look back along the whole beam. {{ovi_n_visible}} cells left a visible O VI shadow, and they merged into a few broad dips. Each cloud is tied by a ribbon to the dips it made.", "physics": "Total log N = log₁₀ Σ N: {{ovi_logN}} for O VI, {{hi_logN}} for H I. Peak τ = {{ovi_peaktau}}: O VI here {{ovi_sat}}. Single cells have b = {{ovi_b_min}} to {{ovi_b_max}} km/s, yet the trough spans {{trough_lo}} to +{{trough_hi}} km/s: motion, not heat, sets its extent.", "hint": "Click a ribbon to see one cloud's share." }, "B12a": { "chip": "The telescope", "display": "A blurry telescope *merges dips.*", "display_short": "Blur merges dips.", "sub": "Every telescope smears the spectrum a little. Less sharpness means neighbouring dips blend into one.", "sub_short": "Less sharpness blends neighbouring dips.", "narrative": "The light reaches the telescope, and the spectrum fills the screen. Every telescope smears the spectrum a little: with less sharpness, neighbouring dips blend into one.", "physics": "F_obs = F ⊗ G, a Gaussian blur with FWHM = c/R: at R = {{$R}}, FWHM = {{$fwhm}} km/s. A real instrument, such as HST/COS, has broader wings than this bell. absreq compares this with Doppler profiles of b_fid = √(b_th² + (5 km/s)²); the explorer uses Voigt profiles with thermal b only.", "then": [ { "id": "B12a.1", "u": [ 0.5, 1.0 ], "display": "Blur turns *narrow* black dips grey.", "display_short": "Narrow black dips go grey.", "sub": "A narrow black dip comes out grey, as if light got through. The wide hydrogen trough stays black.", "sub_short": "Wide black troughs stay black.", "when": "hi_black", "narrative": "Narrow black dips turn grey, as if light got through, but the wide hydrogen trough stays black.", "else": { "display": "Blur turns *narrow* dark dips grey.", "display_short": "Narrow dips go grey.", "sub": "A narrow dark dip comes out paler, as if more light got through.", "sub_short": "Narrow dips come out paler.", "narrative": "Narrow dark dips come out paler, as if more light got through." } } ] }, "B12b": { "chip": "The telescope", "display": "Longer exposures *beat noise.*", "display_short": "Longer exposures beat noise.", "sub": "Twice as clean needs four times as long. The noise pattern stays the same; only its size shrinks.", "sub_short": "Twice as clean takes four times longer.", "narrative": "Now noise. Twice as clean needs four times as long.", "physics": "S/N is per resolution element, with {{pix_per_resel}} pixels per resolution element at every R: σ_pix = {{$sigma_pix}} at S/N {{$sn}}. One noise draw, fixed by a recorded seed, is scaled by S/N. Noise is the same everywhere and flux is not allowed below zero; real detectors differ. When the noise is large, the plot averages each resolution element (display only; the fit uses every pixel).", "then": [ { "id": "B12b.1", "u": [ 0.5, 1.0 ], "display": "Noise can hide dips, *and invent them.*", "display_short": "Noise hides and invents dips.", "sub": "At low exposure the smaller dip at {{s10_feature_v}} km/s drowns, and chance wiggles look like dips. The white line is the truth.", "sub_short": "The white line is the truth.", "narrative": "At low exposure the smaller dip at {{s10_feature_v}} km/s drowns, and chance wiggles look like dips; at high exposure it comes back." } ] }, "B13": { "chip": "Reading it back", "display": "We fit a few *components.*", "display_short": "We fit *components.*", "sub": "A fit explains the noisy spectrum with a few smooth components, each with an amount, a width and a speed.", "sub_short": "Each has an amount, width and speed.", "narrative": "A fit explains the noisy spectrum with a few smooth components, each with an amount, a width and a speed.", "physics": "Voigt fit at R = {{s11_R}}, S/N = {{s11_sn}}; three precomputed noise draws cycle (first: seed {{fit_seed}}); live fits run only in Explore. Fitted total log N = {{fit_logN}}, against {{ovi_logN}} from every cell on the beam. A fitted width is not a thermometer: at R = {{broad_R}}, S/N = {{broad_sn}} one component has b = {{broad_b}} km/s.", "then": [ { "id": "B13.1", "u": [ 0.3, 0.6 ], "display": "Components are not clouds.", "display_short": "Components are not clouds.", "sub": "One component can draw on gas in several places, and clouds are not cells: one clump, many cells across, can feed several components.", "sub_short": "Many to many. Clouds are not cells.", "narrative": "The components fly back into the scene and land on the clouds that made them, often on more than one. Components are not clouds, and clouds are not cells: a cloud is a connected clump of gas, many cells across." }, { "id": "B13.3", "u": [ 0.6, 1.0 ], "display": "A spectrum tells how much and how fast.", "display_short": "How much, how fast.", "sub": "…but not where, and one width alone is not a thermometer.", "sub_short": "Not where. One width is no thermometer.", "narrative": "A spectrum tells how much and how fast, but not where, and one fitted width alone is not a thermometer." }, { "id": "B13.4", "u": [ 0.6, 1.0 ], "when": "has_invented", "display": null, "display_short": null, "sub": null, "sub_short": null, "physics": "At R = {{invented_R}}, S/N = {{invented_sn}} the fit adds a component with b = {{inv_b}} km/s (total {{inv_logN}}): narrower than the blur can measure, so its width is not constrained. The gas cells explain only a small part of it (CREST β = {{facts2.invented.beta}}).", "else": null } ] }, "B14": { "chip": "Yours", "display": "Now it is yours. Same galaxy, same beam.", "display_short": "Now it is yours.", "sub": "Change sharpness and exposure, pick another of {{ngal}} galaxies, or open this beam in the explorer.", "sub_short": "Try another beam.", "narrative": "Now it is yours: the same galaxy and the same beam. Change the sharpness and the exposure, try another beam from any of {{ngal}} galaxies, or open this beam in the explorer.", "physics": "Sharpness is R, exposure is S/N, the components are the fit: each maps to one control in Spectra.", "then": [ { "id": "B14.1", "u": [ 0.0, 1.0 ], "when": "lite", "display": null, "display_short": null, "sub": "This beam has no cell-by-cell flight yet: you see its library spectrum, and the cells drawn did not make it.", "sub_short": "Library spectrum; drawn cells are not its cells.", "else": null, "narrative": "This beam has no cell-by-cell flight yet: you see its library spectrum, and the cells drawn did not make it." } ] }, "narrative_groups": [ { "h2": "Light", "beats": [ "B0", "B1" ] }, { "h2": "The halo", "beats": [ "B2", "B3", "B4" ] }, { "h2": "Cloud A", "beats": [ "B5" ] }, { "h2": "The quiet", "beats": [ "B6" ] }, { "h2": "Cloud B", "beats": [ "B7a", "B7b", "B7c", "B7d", "B7e" ] }, { "h2": "Halfway", "beats": [ "B8" ] }, { "h2": "Cloud C", "beats": [ "B9" ] }, { "h2": "Cloud D", "beats": [ "B10" ] }, { "h2": "Looking back", "beats": [ "B11" ] }, { "h2": "The telescope", "beats": [ "B12a", "B12b" ] }, { "h2": "Reading it back", "beats": [ "B13" ] }, { "h2": "Yours", "beats": [ "B14" ] } ], "ui": { "gate_hold": "Hold to fly", "gate_watch": "Watch ({{$watch_len}})", "skip_intro": "Skip intro", "read_as_text": "Read as text", "hint_desktop": "Scroll, or hold Space, to follow the light", "hint_touch": "Swipe up to follow the light", "fly": "Fly", "pause": "Pause", "resume": "Resume", "look": "Look", "menu": "Menu", "explore": "Explore", "physics": "Physics", "share": "Copy link to this moment", "replay": "Replay", "ride_another": "Try another beam", "music_on": "Music on", "music_off": "Music off", "open_spectra": "Open in Spectra", "see_3d": "See it in 3D", "stop_counter": "stop {{$stop.k}} of {{$stop.n}}", "odometer": "{{$l_travelled}} kpc travelled", "odometer_ly": "{{$ly_travelled}} light-years travelled", "watch_remaining": "{{$watch_remaining}} left", "drag_look": "Drag to look around", "lite_badge": "Story-lite: library spectrum", "field_fallback": "Showing density while {{$field}} loads", "reduced_motion": "Reduced motion: one still per step", "no_webgl": "This device cannot draw the 3D gas, so you see one still picture with the live spectrum.", "software_gl": "3D is slow on this device, so you see one still picture with the live spectrum. Add ?force3d to try anyway.", "keys_help": "Keys: Space play or pause, arrows step, Page Up and Page Down jump, G grab, Esc release, T colours, R sharpness, N exposure, M music", "tf": { "density": "Density", "phases": "Gas phases", "hi": "H I", "ovi": "O VI", "speed": "Speed along the beam", "speed_cells_only": "Speed: cells only, no velocity data", "speed_cells_only_short": "cells only", "composite": "Phases and clouds" }, "phase_legend": { "cool": "cool", "warm_hot": "warm-hot", "hot": "hot" }, "canvas_label": "{{$beat_title}}: the light at {{$l_travelled}} kpc along the beam", "ride_another_short": "Another beam", "open_spectra_short": "Spectra", "replay_short": "Replay" }, "dock": { "all_through": "All the light gets through", "lead_meter": "{{$ion}} gas crossed", "light_left": "light left at the centre", "black_width": "width of the black core", "light_taken": "light taken", "sharpness": "Sharpness (R)", "exposure": "Exposure (S/N)", "new_noise": "New noise", "truth": "Truth", "damping_wings": "damping wings", "axis_speed": "Speed along the beam (km/s)", "axis_wavelength": "Wavelength (Å)", "cos_caveat": "Real instruments such as HST/COS have broader wings than this bell.", "no_cell": "no cell", "smaller_dip": "a smaller dip", "ghost": "what if", "refit": "Refit", "fit_busy": "fitting", "fit_timeout": "fit stopped early" }, "plaque": { "lay": { "nH": "{{$cell.nH}} hydrogen atoms per cm³", "T": "{{$cell.T}} K", "v": "{{$cell.v}} km/s along the beam", "f": "{{$cell.f}} of its {{$cell.element}} is {{$ion}}", "Z": "{{$cell.Z}} Z⊙ metals", "dl": "{{$cell.dl}} kpc of path" }, "physics": { "nH": "n_H = {{$cell.nH}} cm⁻³", "T": "T = {{$cell.T}} K", "v": "V = {{$cell.v}} km/s", "f": "f_ion = {{$cell.f}}", "Z": "Z = {{$cell.Z}} Z⊙", "dl": "dl = {{$cell.dl}} kpc" }, "rule": "Default (review M3 beauty): a pair of plain rows, grouped digits, no exponents: heat and speed, then the lead ion's share as '1 in N'. The Physics layer shows exactly 4 values (n_H, T, V and the lead ion's share; Z and dl replace them only when the active equation needs them). One value per line, never a dot separator.", "plain": { "tv": "{{$cell.Tw}} K, {{$cell.vw}}", "v_away": "moving away at {{$cell.va}} km/s", "v_toward": "moving toward us at {{$cell.va}} km/s", "v_rest": "at rest", "f": "{{$cell.fw}} {{$cell.element}} atoms is {{$ion}}", "f_most": "most of its {{$cell.element}} is {{$ion}}", "f_half": "about half its {{$cell.element}} is {{$ion}}" } }, "shells": { "chip_letter": "cloud {{$letter}}", "chip_ovi_structure": "O VI structure", "ovi_caveat": "O VI clouds exist only above a density level we chose", "open_edge": "extent is a lower limit here", "threshold": "Surface level: changes the cloud, not the spectrum", "lay_definition": "A cloud is a connected clump of gas in one phase that the beam passes through. Its surface is drawn at a level we choose." }, "film": { "rule": "Caption per chunk names the parameter it isolates (R_content 11). Chunk ids match film.json (U_film).", "captions": { "open": "density: where the gas is", "outskirts": "heat: which gas is warm", "cloudA": "amount: one clump goes black", "too_hot": "speed: where a dip sits", "cell263": "ion share: heat decides the ion", "thread": "place is lost, speed is kept", "cloudD": "amount: deeper, then only wider", "lookback": "metals: an ingredient, not the switch", "telescope": "sharpness and noise", "fit": "how much and how fast, not where", "end": "{{$url}}" }, "end_card_title": "How a spectrum is made", "honesty_heading": "What we simplified" }, "physics_layer": { "heading": "Physics", "cells": "{{n_kernels}} smoothing kernels touch the beam; about {{n_crossed}} cells are actually crossed.", "units": "Metal content is in solar units (Z⊙). Speeds are in km/s along the beam, measured from the galaxy; positive means moving away from us.", "honesty_heading": "What we simplified" }, "honesty": [ "One frozen snapshot at z = 0: light takes about {{light_crossing_myr}} million years to cross this path, while real gas would move.", "No expansion of space along the beam; it would add up to {{hubble_kms}} km/s.", "Dip widths come from heat only; no turbulence is added.", "No Milky Way foreground, no gas beyond the halo, no blends with other ions.", "O VI's second transition lies off the plotted speed range.", "The telescope blur is a Gaussian; real instruments such as HST/COS have broader wings.", "One noise draw, fixed by a recorded seed, is scaled by S/N.", "On narrow screens a noisy spectrum is averaged over neighbouring pixels for display only, so it stays readable; the noise level shown is per pixel.", "{{pix_per_resel}} pixels per resolution element at every R.", "The pacing is time-warped: the camera slows where absorption happens. The odometer shows the true distance.", "The fog is a smoothed grid, and its colours are our choice, not light the gas gives off.", "The beads are smoothing kernels: {{n_kernels}} touch the beam, and about {{n_crossed}} cells are actually crossed.", "The small gas splats beside the beam cannot be picked.", "O VI clouds exist only above a density level we chose; at lower levels the O VI joins into one medium.", "Warm-hot cloud extents are lower limits: the search stops at the edge of a tube around the beam.", "Star streaks are a motion cue, not physics." ], "credits": { "heading": "Credits and methods", "items": [ "Simulation: IllustrisTNG, TNG50-1 (Nelson et al. 2019a, 2019b; Pillepich et al. 2019), used as the TNG Collaboration requests.", "Spectra: Trident (Hummels, Smith & Silvia 2017) on yt (Turk et al. 2011).", "Ionisation: the Haardt & Madau (2012) UV background tables.", "Cloud finding: techniques adapted from Lucchini, Han, Hernquist & Conroy (2024) and Lucchini et al. (2025, ApJ 990, 118), which build on Nelson et al. (2020) and Ramesh et al. (2023). No code was copied.", "Cell and component attribution: CREST (T. Singh), which re-runs Trident's deposition per cell and splits each fitted component among the cells and clouds that made it.", "vortrace (Beane & Smith) was evaluated and is not used or vendored; the count of crossed cells comes from nearest-generator sampling.", "Equations typeset with KaTeX (MIT); 3D with three.js (MIT); fonts Newsreader, Space Grotesk and JetBrains Mono (SIL Open Font Licence)." ], "methods": [ "Clouds are connected groups of gas cells, linked by Voronoi neighbours in position and speed, with a density level chosen so that one structure does not swallow the halo. The level is logged, and a ladder of precomputed levels drives the surface handle.", "O VI clouds exist only above that chosen level; below it the O VI joins into one medium. Warm-hot extents are lower limits at the edge of the search tube.", "Each fitted component is split among cells by CREST responsibilities; a component that no cell explains is shown as no cell." ] }, "flags": { "about": "Booleans exported per story by U_data (story JSON `flags`), each from the R_content 10 rule for any of the galaxies. A missing flag counts as false, so the conservative branch shows.", "has_first_ovi": "some cell in flight order has O VI τ₀ > 0.05 (B4)", "hi_black": "a cool cloud crosses the beam with H I peak τ₀ > 1 (B5, B10, B12a)", "has_ovi_skin": "O VI cells within 10 kpc of that cool cloud with |ΔV| < 20 km/s (B5 skin sentence)", "has_hot_stretch": "a stretch of at least 40 kpc with median T > 10⁶ K and no visible cells (B6 first line)", "ovi_strong": "O VI peak τ ≥ 0.1 (B7b)", "has_cold_knot": "an H I group within 15 kpc of an O VI group with |ΔV| > 50 km/s, positions from spectral minima (B7e)", "has_pair": "the v1 S6 pair rule finds a pair (τ₀ > 0.05, |ΔV| < 0.5 min b, |Δℓ| ≥ 50 kpc) (B9 thread)", "has_invented": "the page fits hold a component narrower than b for O VI at 30 000 K that the cells claim under a quarter of (CREST β < 0.25), as exported by U_data in facts2.flag_rules (B13 invented example; 488530: β = 0.088, column share 0.064). Replaces the earlier '< 5 % summed responsibility', which no reading meets on 488530. Pending science review.", "lite": "story-lite: no cell-by-cell data for this beam (B14 honesty line)", "richest_not_closest": "the richest O VI stretch (largest O VI group by column) does not contain the closest-approach point, so 'closest does not mean most gas' holds (B8, M14)", "has_b9_new_dips": "the B9 window gains at least one new O VI spectral minimum (U_data facts2.b9_new_minima non-empty; review2 science M1: minima of the partial spectrum, not peaks of the optical depth gained); gates B9's entry, which quotes {{b9_new_minima}}. Without it B9 says only that no new dip appears." }, "derive": { "about": "Analogies and number words are generated from keys by these rules, never typed. Reference evaluator: deriveKeys() in tests/js/story_copy_lint.mjs. Each rule needs a science sign-off (status).", "cloudA_xHI_one_in": { "from": [ "cloudA_xHI" ], "rule": "one_in", "text": "1/x rounded to one significant figure; written as a word up to twenty, otherwise as a grouped number (0.09 gives ten)", "status": "pending science review" }, "hot_xHI_one_in": { "from": [ "hot_xHI" ], "rule": "one_in", "text": "as above (5×10⁻⁶ gives 200 000)", "status": "pending science review" }, "xHI_ratio": { "from": [ "cloudA_xHI", "hot_xHI" ], "rule": "ratio_1sf", "text": "a/b rounded to one significant figure, grouped (0.09 / 5×10⁻⁶ = 18 000 gives 20 000), always shown after 'about'", "status": "pending science review" }, "c263_ovi_share_words": { "from": [ "c263_ovi_share" ], "rule": "fraction_words", "text": "a share in % written as half, a third, a quarter, a fifth or a tenth when within 10 % (relative) of it, otherwise 'N %' (24.7 gives a quarter)", "status": "pending science review" }, "light_crossing_myr": { "from": [ "length_kpc" ], "rule": "light_myr", "text": "path length in kpc times 3261.56 light-years per kpc, in millions of years, one decimal (493 gives 1.6)", "status": "unit conversion" }, "xHI_ratio_shown": { "from": [ "cloudA_xHI", "hot_xHI" ], "rule": "ratio_1sf", "text": "review M3: the ratio of the two rounded keys shown on screen, to one significant figure (0.08 / 5×10⁻⁶ gives 20 000), so it agrees with the two 'one in' numbers beside it; the exported xHI_ratio key (unrounded) is not used in copy", "status": "pending science review" } }, "keys_contract": { "about": "Keys the copy reads that story-data/1 does not have. DESIGN_final 3.6 names the first group (U_data must export them); the second group is requested by U_copy from U_data (same formatting as v1 keys: display strings, digit groups with a space, unicode minus and superscripts). frac_before_l0 per ion is exported by U_data as ovi_frac_half / hi_frac_half (percent strings), and the copy uses those names.", "design_3_6": [ "n_kernels", "n_crossed", "n_pairs", "cloudA_xHI", "hot_xHI", "cloudA_core_T", "cloudA_core_bH", "cloudA_core_bO", "b3_ovi_depth", "b4_first_depth", "b5_ovi_depth", "b5_ovi_drop", "b5_ovi_depth_after", "b9_new_dips", "b9_new_minima", "b9_deepened_minima", "ovi_T_hot_fade", "ovi_T_cool_fade", "v_gal", "ovi_frac_half", "hi_frac_half" ], "requested_by_copy": { "c263_ovi_share": "share of the beam's O VI column in the S5 cell, in % (24.7 for 488530)", "b7e_hi_v": "H I position of the second cool cloud (cold_knot): its cloud's own spectral minimum, signed km/s (+37)", "b7e_ovi_v": "O VI clouds beside it: each cloud's own spectral minimum, signed km/s joined by 'and' (−55 and +14)", "s10_feature_v": "select.S10_feature.V_kms as a signed display string (+96)", "pix_per_resel": "pixels per resolution element of the noise model (5)", "flags": "object of booleans named in copy.flags (shipped 2026-11-12 11:37 with facts2.flag_rules)" }, "status": "all requested keys and flags ship in story-data/2 (U_data regeneration 2026-11-12 11:37)" }, "live": { "about": "Runtime values filled by the shell, dock or plaque from FrameState or controls; never typed numbers.", "fields": [ "$watch_len", "$watch_remaining", "$stop.k", "$stop.n", "$l_travelled", "$ly_travelled", "$cell.nH", "$cell.T", "$cell.v", "$cell.f", "$cell.Z", "$cell.dl", "$cell.element", "$ion", "$R", "$fwhm", "$sn", "$sigma_pix", "$letter", "$field", "$url", "$beat_title", "$T", "$cell.Tw", "$cell.vw", "$cell.va", "$cell.fw" ] }, "rules": { "plain_language": { "R": "sharpness (R in the Physics layer)", "S/N": "exposure (S/N in the Physics layer)", "column density": "amount (log N in the Physics layer)", "absorption line": "dip", "sightline": "beam", "line-spread function": "blur", "component": "component (B13 only, where the lesson needs the word)", "temperature": "heat in display lines; T with units in the Physics layer", "meters": "'{{$ion}} gas crossed', 'light left at the centre', 'width of the black core', 'light taken'" }, "analogies": [ { "id": "siren", "where": "B6.1", "text": "like a siren", "basis": "Doppler shift; qualitative, no number", "status": "pending science review" }, { "id": "one_in", "where": "B5.1", "text": "one hydrogen atom in N keeps its electron", "basis": "derive.cloudA_xHI_one_in / hot_xHI_one_in", "status": "pending science review" }, { "id": "ratio", "where": "B5.1", "text": "about N times fewer", "basis": "derive.xHI_ratio", "status": "pending science review" }, { "id": "quarter", "where": "B7b", "text": "a quarter of all the O VI", "basis": "derive.c263_ovi_share_words", "status": "pending science review" }, { "id": "sqrt_t", "where": "B12b", "text": "twice as clean needs four times as long", "basis": "S/N grows as the square root of exposure time (photon counting); exact, not data-dependent", "status": "pending science review" }, { "id": "jiggle", "where": "B7b.1", "text": "hotter ions jiggle faster", "basis": "thermal speed b = √(2kT/m); qualitative", "status": "pending science review" } ], "positions": "A dip position on screen is a spectral-minimum key (b7e_*, b9_new_minima, s10_feature_v), never an N-weighted mean of cells (C_science H2).", "cells_wording": "Display says 'hundreds of gas cells' only for the cells the beam touches (n_kernels); it never says hundreds of cells make the dips (v1 review P0-6: only ovi_n_visible leave a visible O VI shadow). Counts appear only in the Physics layer: n_kernels kernels touch, about n_crossed are crossed. ncross and n_cells are banned in copy." }, "lint": { "allow": [ { "re": "\\b3D\\b|force3d", "why": "the name of the 3D view and its URL flag" }, { "re": "TNG50-1", "why": "simulation name" }, { "re": "TNG50", "why": "simulation name" }, { "re": "R200c|M200c", "why": "halo radius and mass symbols" }, { "re": "z = 0", "why": "snapshot redshift is the definition of the data set (meta.redshift); stated once in Physics and honesty" }, { "re": "\\(5 km/s\\)²", "why": "absreq's fixed non-thermal floor in b_fid, quoted from absreq/lines.py (the parent project's convention, not a story number)" }, { "re": "b_th²|χ²", "why": "symbol with a squared exponent" }, { "re": "cm⁻³|cm³", "why": "unit" }, { "re": "10⁶ K|10⁻⁶", "why": "rule definitions in `flags` (not shown on screen)", "sections": [ "flags", "derive" ] }, { "re": "\\b(19|20)\\d\\d[ab]?\\b|ApJ 990, 118", "why": "bibliographic years and journal reference", "sections": [ "credits" ] }, { "re": "\\d", "why": "rule text for builders, not shown on screen", "sections": [ "flags", "derive", "keys_contract", "meta", "rules", "plaque.rule", "film.rule", "lint" ] } ], "allow_words": [ { "re": "Twice as clean needs four times as long|Twice as clean takes four times longer", "why": "square-root law of photon noise (rules.analogies sqrt_t)" }, { "re": "(a|even a) sixth electron", "why": "O VII is oxygen with six electrons lost; definition of the ion, not data" }, { "re": "three precomputed noise draws", "why": "page_fits holds three seeds (pipeline constant of v1, physics layer only)" }, { "re": "hundreds of gas cells", "why": "D5: display says hundreds of cells for the kernels the beam touches (n_kernels)" }, { "re": "half its peak", "why": "definition of the fade temperatures ovi_T_hot_fade / ovi_T_cool_fade (C_science M5)" }, { "re": "\\bhalf\\b", "why": "rule text for builders", "sections": [ "flags" ] } ] } }