TAPIR Theorecal AstroPhysics Including Relavity & Cosmology hp://www.tapir.caltech.edu

Chrisan O co@tapir.caltech.edu, Cahill Center for and Astrophysics, Office 338 TAPIR: Third Floor of Cahill, around offices 316-370 ∼20 graduate students 5 senior researchers ∼15 postdocs 5 professors 2 professors emeritus lots visitors TAPIR Research TAPIR Research Topics

• Cosmology, Star Formaon, Evoluon, Parcle Astrophysics

• Theorecal Astrophysics

• Computaonal Astrophysics

• Numerical Relavity

• Gravitaonal Wave Science: LIGO/eLISA design and source physics

TAPIR – Theorecal AstroPhysics Including Relavity 3 TAPIR Research Professors: Sterl Phinney – gravitaonal waves, interacng black holes, neutron stars, white dwarfs, Yanbei Chen – general relavity, gravitaonal wave detecon, LIGO Phil Hopkins – cosmology, galaxy evoluon, star formaon. Chrisan O – supernovae, neutron stars, computaonal modeling and numerical relavity, LIGO data analysis/astrophysics.

Acve Emeritus Professors: Peter Goldreich & Senior Researchers (Research Professors)/Associates: Sean Carroll – cosmology, extra dimensions, quantum , DM, DE Curt Cutler (JPL) – gravitaonal waves, neutron stars, LISA Lee Lindblom – neutron stars, numerical relavity Mark Scheel – numerical relavity Bela Szilagyi – numerical relavity Elena Pierpaoli (USC,vising associate) – cosmology Asantha Cooray (UC Irvine,vising associate) – cosmology

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 4 Cosmology & Structure Formation Today

- HOW DO WE GO FROM TO MILKY WAY? Phil Hopkins, 330 Cahill

z~1090 (t~400,000 yr) ?

Ø Formaon of structure in the (just gravity?) Ø Probes of dark maer & Ø How can we make progress in the “next generaon” of cosmology experiments? LMC The Interstellar &

Intergalactic Medium

- TURBULENCE & PHYSICS ON SCALES ~ 1012 - 1028 cm Phil Hopkins, 330 Cahill

Ø Gravity Ø Turbulence (super-sonic up to Mach~100) Ø Magnec Fields Ø Cosmic Rays & relavisc parcles Ø Radiaon Ø Cooling processes & molecular chemistry Ø Star & Formaon/Growth Inter-stellar medium phases: Ø “Feedback”: Stars, supernovae, black holes “cold” (blue), “warm” (pink) and “hot” yellow Galaxy Formation & Evolution Phil Hopkins,

- WHY DO OUR MODELS FAIL SO BADLY ? 330 Cahill

Ø How do grow? What happens when they hit each other (collisional & collisionless dynamics)? Ø What physics are we missing that explains why galaxies are so “under-massive”? Ø Can their structure constrain the nature of dark maer? Star & Planet Formation

- WHAT’S HAPPENING ON SCALES CLOSER TO OUR OWN?

Collapse of a disk around a young star to form a giant planet by gravitaonal instability

see Phil Hopkins, 330 Cahill

Ø How do stars actually form? Why do they have the masses they do? (radiaon vs. gravity?) Ø How do massive stars impact galaxies: explosions, ionizing radiaon, super-winds? Ø How can we form the diversity of planets we are seeing? Is there more than one way to do it? Super-Massive Black Holes

- THE “MONSTERS” AT GALAXY CENTERS

“Jet” of relativistic particles from black hole

Gas disk in galaxy center sees the “photon wind” from black hole

see Phil Hopkins, 330 Cahill Gas in Perseus Cluster ~ millions of light years Ø How do they form? Are exoc physics involved? “blown out” by a single black hole! Ø How do they accrete material? How does this radiate and “shine”? How can we observe it? Ø How does the black hole (and its relavisc jets, accreon disks) interact with the galaxy? TAPIR Research High Energy Astrophysics (Theory)

● Subjects of research at Caltech

● White dwarfs with binary companions

– Tides, accretion

– Make supernovae (Ia, 0.1a), (AIC), AM-CVn gravitational waves

– Explosive pace of recent observational discoveries

● Neutron stars with binary companions

– Accretion, irradiation, evaporation

– Make X-ray binaries, Pulsars, Gamma-ray bursts, , ultra-high energy cosmic rays, gravitational waves

● Black holes with companions

– Tidal disruption events, circumbinary disks

– Make radio-X-ray flares, gravitational waves, galaxy feedback...

● Close connection with observational programs at Caltech (Profs. Harrison, Prince, Kulkarni, Hallinan):

– X-rays (NuSTAR), Optical (Palomar Transient Factory, Keck), LIGO

See Prof. Sterl Phinney, 316 Cahill

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 10 TAPIR Research

Textbook story TIME

1) Old, dead, field-decayed + <1Msun main sequence star 2) Magnetic braking 3) Low Mass X-ray binary (LMXB) -spinup of 4) Accreting Millisecond X-ray Pulsar (AMXP) 5) Millisecond Radio Pulsar (MSP) -now also brought to you on your gamma-ray dial (Fermi). X-ray heating

Sterl Phinney, 316 Cahill Possible heating by relativistic pulsar wind 2 TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 11 TAPIR Research Textbook story -2

Millisecond Radio Pulsar (MSP) Companion remnants can be:

● White dwarf (0.15-1.3Msun)

● M-star (~0.3Msun) “Redbacks” ● Brown Dwarf (~0.02Msun) “Black Widows” Possible heating by relativistic ● Planet[s] (Earth mass -Jupiter mass) pulsar wind

● Nothing (Isolated recycled MSP)

Last 2 years: Textbook story is wrong! Some big questions: ● Are Redbacks progenitors/descendants/cyclical phase of X-ray binaries? ● How does physics of heating of companions to LMXB, MSPs work? ● Tidal heating Sterl Phinney, ● X-ray heating 316 Cahill ● Pulsar wind/ heating ●Can the heating cause (observed) bloating, evaporation of companion?

● What causes the (observed) orbital period changes, eccentricities? 3 TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 12 TAPIR Research Black Widow Pulsars (Neutron Star+ Brown Dwarf):

Pulsar-facing Side of companion Heated (most of Examples: Incident pulsar wind PSR B1957+20 Flux) PSR J2051-0827 PSR J2214+3000 Radio eclipses: wind PSR J2241-5236 From brown dwarf PSR J1719-1438 (Jupiter, C)

0FGL J2239.8-0530 (weak radio)

Sterl Phinney , 316 Cahill

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 13 TAPIR Research One example: How does a pulsar's ultrarelativistic wind actually heat its companion? Sterl Phinney, 316 Cahill Pulsar wind particles

Photosphere at 4000K

Photosphere At 6000K

Interior of companion star

GEANT-4 airshower MonteCarlo 5 To determine heating vs depth; model atmosphere to determine radiated spectrum.

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 14 TAPIR Research Theorecal Relavity (Chen, Thorne) • Predict and understand numerical relavity discoveries. • Perturbaon theory: Extreme-mass-rao inspiral into Kerr BHs. • Development of analycal gravitaonal wave templates. • LIGO data analysis techniques. • Tidal interacons of black holes. • Tests of relavity and alternave theories of relavity. • Design of 3rd-generaon gravitaonal wave detectors (LIGO 3, quantum non-demolion, macroscopic quantum mechanics, BBO=Big Bang Observatory) -> See Yanbei Chen, postdocs and grad students on Friday!

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 15 2 Visualizaon/Analycal Modeling of Black-Hole Mergers Visualization/Analytical Modeling of Black-Hole Mergers • How• How should we best should we best visualizevisualize the space-time numerical relavity obtained by spacemesnumerical relativity?? • What• What is the is the qualitativestructure structure of the binary black-hole merger space-me? of the binary black-hole merger space-time? 17 • How• How can we beer can we better understandunderstand the waveforms the waveforms these binaries emit? these binaries emit? 3 II. A DETAILED DESCRIPTION OF THE # METHOD 300 C # mostly tail transition A. Further Motivation !ringdown !merger 250 # Before going into the details of our procedure, it is D mostly worth spending some time discussing why our specific inspiral implementation of PN and BHP theories will help avoid 200 direct part" some of the difficulties that arose in other methods in the !infall

t g introduction and noting the limitations and assumptions f that underlie our approach. 150 B It is certainly hard to argue that existing orders of e PN (up to v6 in the metric, for near-zone dynamics [22]) 100 See Prof. Yanbei Chen and BHP (up to second order for Schwarzschild, see [23] for details! 318 Cahill for a gauge-invariant formulation) theories are accurate in the whole space, simultaneously. Nevertheless, it is Newtonian interior

! plausible to argue that these approximation techniques 50 exterior cover different spatial regions at different times in a way

Post BH perturbation such that each theory is either valid to a reasonable level A of accuracy or occupying a portion of that will 0 !50 0 50 100 150 200 not influence physical observables where it fails. Using an approach of this type, we aim to get the most out of r" the approximation methods. space-me vortexvortex curves depicng the spacemeFIG. diagram of a head-on BH collision and 11: Tendex lines in the equatorial plane for a rotating FIG. 10: Samespace-time as Fig. 9 but zoomedcurves depicting out to show the the wave Specifically, we find that the following procedure gives FIG. 1: (Colorcurrent online)space-time quadrupole This figure diagram in depicts linearized a of spacetime a theory. dia- The curves shown zone. In the“frame-dragging“frame-dragging” wave zone, the” lines effect of a binary effect generically of a binary collect into span interpretaon of the waveform i- 16 good agreement with the waveform of a numerical- gram of aare black-hole lineshead-on of collision, identically black-hole modeled zero after collision tendicity, Price’s descr enforcedip- by symmetry. rals, which form the boundaries of vortexes (regions of con-tion of stellar collapse. We choose the trajectory of the two relativity simulation presented in Sec. III. First, we have The lines are shaded by the absolute value of the tendicity centrated vorticity). holes asand a way an to interpretation separate the spacetime of the into waveform an interior the reduced mass of the binary follow a plunging geodesic and an exteriorof the region. other Thetwo exterior tendex region lines is that a perturbed, cross the linesin the shown, Schwarzschild but spacetime. Then, we divide this tra- black-holeare spacetime, not tangent whereas to the the interior plane, is that and of a have post- equaljectory and in opposite half to make a coordinate radius (and thus a Newtoniantendicities. (PN) black-hole-binary system [shaded in yellow coordinate sphere) that passes through the centers of the of Fig. 6b. At the transition to the wave zone, the vortex(light gray)]. The red (dark gray) region of the diagram shows black holes. The set of all the coordinate spheres de- the place at which the effective potential of the black hole is fines a time-like surface in spacetime. Finally, we apply lines fail to curve back into the central region and insteadsignificantly greater than zero. This formalism allows us to PN theory within this time-like surface and BHP on the bend outward, joining a wave-zone spiral pattern. divide the waveform into three sections: inspiral (or infall), exterior. The two theories must agree on this time-like which extends from the beginning of the binary’s evolution surface, which we will subsequently call the shell. That spiral pattern consists of four vortexes (regionsuntil when the l =2effective potential of the exterior BHP of concentrated vorticity) that spiral outward and back-spacetime starts to be exposed; merger, which extends from Matching PN and BHP theories on this shell has cer- tain advantages. Because BHP theory relies upon a mul- ward as the quadrupole rotates. These four regionsthe of end of inspiral to when the majority of the exterior poten- tial is revealed;under and the ringdown, reflection. which represents The diagram the remain in- Fig.tipole 11 shows expansion, the this makes it necessary to treat the PN alternating positive and negative vorticity are boundedder. We overlaysingle the family even-parity, of tendex (l =2,m lines=0)modeofthe tangent tointerior the symmetry in terms of multipoles of the potentials. For one, waveform. this is useful, because physical observables like the radi- by tight clusters of vortex lines, just outside of which the plane. As these curves have exactly zero tendicity, they sign of the dominant vorticity changes. ated energy and momentum very often do not need many are physically relevant only in that they denotemultipoles the orien-to find accurate results. (In fact, in our exam- This same rotating vortex structure occurs in the case tation of the other two families of tendex lines,ple in whichSec. III, are we see that the quadrupole perturbations of an l =2,m = 2, odd-parity (current quadrupolar) not tangent to the plane, but whose projectionalone su ontoffice.) the Second, a multipole expansion may also perturbation of a Schwarzschild black hole (Paper II in plane must be orthogonal to the curves shownbe helpful (because for the convergence of the approach. For two this series). There the horizon vorticity pattern takes the point particles, for example, each multipole component all three curves are mutually orthogonal). Theof the shading Newtonian of potential U (l) at the location of the place of the current quadrupole. N the lines in Fig. 11 does not represent the tendicityparticles satisfies of theU (l) < M/R,whereM is the mass of In Fig. 11 we indicate the structure of the tendex linesholes. In Sec. III, we present an explicit calculation for N the head-onlines collision drawn of (which two black is holes identically with transverse, zero), butthe rather binary ofand theR is the∼ distance from the center of mass. on the equatorial plane. Because the symmetry prop- other two tendex lines, which intersect theThis lines is small drawn for much of the infall, when R M,and anti-aligned spins, and we compare waveforms, radiated " erties of the system imply different constraints on theenergy and radiated linear momentum, from our model even when the binary reaches what will be the peak of the with mutually equal and opposite tendicity. Again, this (l) with the equivalent quantities from a full5 numerical-4 effective potential of the merged black hole, U 1/3. tendex field than on the vortex field, some explanation shading is rescaled by (kr) /[1 + (kr) ]. Though it isn’t N ∼ is needed. The plane in which this and the previous tworelativityapparent simulation. to In the Sec. eye, IV the we discuss strength how of our the tendicityBecause grows the effective potential of the final black hole method can help interpret4 the waveform during merger, tends to mask perturbations5 within (as they are red- figures are drawn is a plane of reflection symmetryand for finally,only in Sec. as r V,near we conclude. the singular We will pointuse geometri- (origin),shifted rather and than cannotr escape), our hope (supported by the the problem. However, because the source is a pure cur-cal units (asG for= c = the 1) vorticity. and Einstein As summation argued convention early in Sec.example VI C, this in Sec. can III) is that PN theory is still reason- rent quadrupole, it must be antisymmetric under reflec-throughoutbe this interpreted paper. intuitively as meaning thatably the vorticityaccurate at is the peak of the potential. Then, in our tion across this plane (as such a reflection is a parity sourced directly from the current quadrupole, while the inversion). The vorticity, which itself has an odd parity tendicity is sourced by induction from the time-varying relationship with its source, is symmetric under this re- vortex field. flection, constraining the vortex lines to be either tangent or orthogonal to the plane, as noted above. The tendic- ity is antisymmetric under this reflection, so one family For a rotating mass quadrupole (e.g. the quadrupole of lines can be tangent to the plane, so long as it has moment of an equal mass binary), the tendex lines in the zero tendicity, and two other families of lines must cross plane of reflection symmetry will have precisely the same the plane at equal and opposite inclinations, with equal form as the rotating-current-quadrupole vortex lines of and opposite tendicities, such that they are exchanged Figs. 9 and 10; see Sec. VIF. Observaons with Observations withAdvanced LIGO Advanced LIGO & beyond& Beyond 3 • Improved LIGO search strategies Improve LIGO search strategies • “ ” - Create more efficient - create more efficient “searchsearch templates templates” that that incorporate beer understanding of binary incorporate better understanding of binary black-hole black-hole waveforms. waveforms - design algorithms that help detect and sky-localize a - Design algorithms that help compact binary before the mergerdetect and sky- (or resonant localizeshattering a compact binary before the merger ) takes place (or resonant shaering) takes place • Search for “signatures of relativity” in DaveTsang et al., 2011, PRL Tsang et al., 2011 • Search for gravitational“signatures of relavity waveforms ” in gravitaonal waveforms, e.g., - e.g., distortion of horizondistoron caused of the in a binary.by a partner • “Alternave theories of gravity” [movated by string theory and • “Alternative theories of gravity” [motivated cosmological consideraons] by string theory, or cosmological - What are the GWs they predict? considerations] - What are the GWs they predict? - How can we search for them with - How can we search for them in LIGO LIGO? data? See Prof. Yanbei Chen for details! 318 Cahill 17 Quantum Mechanics of kg-scale Objects LIGO sensivity δx ~ 10−18 meter M = 11kg

m = M / 4

• Advanced LIGO (and beyond) will be limited by the Heisenberg Uncertainty of kg-scale mirrors. • How can we use LIGO (and other “optomechanics” experiments) to explore macroscopic quantum mechanics and other physics? – Does “quantum-state reducon” work the same way for kg-scale objects? – Can we entangle such objects? Teleport their quantum states? – Can we see quantum-gravity effects? What about “emergent-gravity” effects? See Prof. Yanbei Chen 18 for details! 318 Cahill TAPIR Research: Numrel – hp://www.black-holes.org • Why? Numerical Relavity – Understand fundamental predicons of relavity not amenable to analycal work. – Predict gravitaonal waveforms for LIGO & eLISA. – Study consequences for astrophysics: BH spins, BH growth, BH kicks, gamma-ray bursts, dal disrupon of neutron stars, supernovae. • What and How? – Many ways to write Einsteins equaons – not all allow stable numerical evoluons -> find those that do. – Efficient numerical implementaon & high-performance compung -> new 2400-core supercomputer here at Caltech! – Study BH-BH, NS-NS, and NS-BH binary coalescence and merger. – Close collaboraon with colleagues at Cornell, CITA, WSU, CS Fullerton. -> See Chrisan O, Mark Scheel, Bela Szilagyi, students and postdocs!

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 19 First successful black-hole binary computation: Pretorius 2005 Today several research groups worldwide have NR codes.

TAPIR Research: Numrel – hp://www.black-holes.org

Numerical relativity (NR) Write Einstein’s field equations as an initial value problem for gµ⌫. Constraints (like B = 0) Gµ⌫ = 8⇡Tµ⌫ r · ) Evolution eqs. (like @t B = E) ⇢ r ⇥ Choose unconstrained data on an initial time slice Choose gauge (=coordinate) conditions

Get yourself a computer cluster, and Solve constraints at t = 0 (For us: 4 (+1) coupled nonlinear 2nd-order elliptic PDEs) Use evolution eqs. to advance in time (For us: 50 coupled nonlinear 1st-order hyperbolic PDEs)

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 20

() March 26, 2013 1 / 9 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

21 22 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

23 Understanding how Gravitaonal Waves are emied: Owen et al. 2011, Physical Review Leers, Frame-Dragging Vortexes and Tidal Tendexes Aached to Colliding Black Holes: Visualizing the Curvature of Spaceme.

-> Gravito-magnec/Gravito-electric field lines. Interface between theorecal and numerical relavity. 24 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

By postdoc Roland Haas and graduate students Jonas Lippuner & Jeff Kaplan 25 26 Supernovae! “Nova Stella” – New Star

Tycho Brahe (1572): „De Nova Stella“ Fritz Zwicky 1898-1974

Walter Baade 1893-1960 “Supernova” (1934)

[PNAS, 20:259, 1934] [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005] Why do we care about Supernovae? • SNe are the main cosmic polluters.

Source: NASA • Dynamical impact on galaxy evoluon. • Stellar collapse: The making of neutron stars and stellar-mass black holes. – Formaon and co-evoluon of black holes and galaxies. – Core-collapse SN – Gamma-Ray Burst [GRB] relaonship. • Cosmic standard candles. 29 TAPIR Research: Computaonal Relavisc Astrophysics Computaonal Relavisc Astrophysics (O) • Supernova Theory and Modeling – 2D/3D models stellar collapse and core-collapse supernovae. – Black Hole Formaon and Gamma-Ray Bursts. – transport, GR magnetohydrodynamics. – Predicon of gravitaonal wave signals for LIGO & LIGO detecon / data analysis strategy. – Stellar evoluon and nucleosynthesis. • Neutron Star Simulaons – Nonaxisymmetric rotaonal instabilies in rapidly spinning newborn neutron stars. – Understanding the evoluon of hypermassive NSNS merger remnants. -> See grad students Jonas Lippuner, John Wendell, Sherwood Richers TAPIR 30 TAPIR Research: Computaonal Relavisc Astrophysics Open Source Astrophysics Codes (O) • Einstein Toolkit hp://www.einsteintoolkit.org – Open source set of codes to evolve Einstein’s equaons. – GR Hydrodynamics; GR-MHD under development. – Collaboraon with RIT, GATech, LSU, Perimeter Instute • GR1D – a new open-source code for stellar collapse and BH formaon hp://www.stellarcollapse.org – Modern 1.5 D (spherical symmetry + rotaon) code developed for extensive parameter studies. – Includes complicated microphysics and neutrino treatment. – Developed by graduate student Evan O’Connor.

TAPIR 31 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

32 The Supernova Problem

Animaon Radius (km) by Evan O’Connor

C. D. O @ Caltech, Ph242, 2012/01/20 33 [Wilson 1985; Bethe & Wilson 1985] Understanding the Mechanism of Core-Collapse Supernova Explosions

[O 2009] 34 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

35 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

36 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005]

37 [Thompson et al. 2003, Rampp & Janka [Wilson 1985; Bethe & Wilson 1985] 2002, Liebendoerfer et al. 2002,2005] Making Black Holes!

38 Theorecal AstroPhysics Including Relavity

Please come and meet us! hp://www.tapir.caltech.edu -> Third Floor of Cahill, around offices 316-370

TAPIR – Theorecal AstroPhysics Including Relavity and Cosmology 39