Magnetic fields of compact objects
コンパクト天体磁場
Kazumi Kashiyama (U. of Tokyo)

Compact objects and magnetic fields
コンパクト天体と磁場
Kazumi Kashiyama (U. of Tokyo)

Why compact objects?
= white dwarfs (WDs), neutron stars (NSs), and black holes (BHs)• As a laboratory of extreme physics• As a high-energy astrophysical object• What kind of compact objects produce what kind of emission?
• How and when?

• As a beacon from the universe far far away
• As an end product of stellar evolution• What kind of stars produce what kind of compact objects?
• How and when?

Sullivan 08

Yasuda et al. 19

MR [mag]

Optical-transient zoo (~2000)
-26
-24
-22
-20
-18
-16
-14
-12
-10
-8
-6
0.01

e
SN

Ia

CCSNe

Classical Novae

0.1

1
10
Time [days]

LBVs

100

MR [mag]

Optical-transient zoo (~2020)-26
GRB afterglows
-24
-22
-20
-18
-16
-14
-12
-10
-8
-6
0.01
0.1

Luminous SNe

Shockbreakout
Kilonovae

Fast
Blue
OpticalTransient

TDEs

Iax
Ca-richIntermediate Luminosity
Red Transients
Luminous Red Novae

1
10Time [days]

100

c.f., binary BH merger
The first detection in 2015
Now

c.f., detection of a binary NS merger (2017)

c.f., high-energy neutrinos
Discovered 2013

Ke & Murase 17

c.f., fast radio burst (FRB)
Discovered 2007, established ~2013
Lorimer+07

Figure 2: Frequency evolution and integrated pulse shape of the radio burst. The survey data,collected on 2001 August 24, are shown here as a two-dimensional ‘waterfall plot’ of intensity
as a function of radio frequency versus time. The dispersion is clearly seen as a quadratic sweep
across the frequency band, with broadening towards lower frequencies. From a measurement of

Now ~1000 events (a few 10 with known redshift)Credit: ESA and NASA

Russel 1914

Russel 1914

Copyright: ESA/Gaia/DPAC

Known knowns about WDs
How they born

When they accrete gas,nova!
©M.Kornmesser

How they cool down

When they explode,thermonuclear supernova!
© Sihao Cheng© Williams et al. 16• Known unknowns about WDs
WD formation in general
Future of the solar system?

?
?

How the most massive and magnetized WDs are formed?
White dwarf “pulsars” ?

Copyright: ESA/Gaia/DPAC
How extremely low mass WDs are formed?

?

Oldest white dwarfs
How they are?
Where they are?

Super Chandrasekhar WDs collapse into NSs?
c.f., a repeating FRB source in a globular cluster (GC)FRB hosting GC

M81
Kirsten et al. 21; Nimmo et al. 21;…

When and how are transients powered by radioactivity?
Taubenberger 17

Binary WD mergers and their remnantsCredit: NASA/Dana Berry, Sky Works Digital

mHz GWs

Type Ia
supernova
NASA/CXC/Rutgers/J.Warren & J.Hughes et al.

WD merger remnant

Highly magnetizedmassive white dwarf…
[ESO/L. Calçada]Collapse into neutron star
GRB? FRB?
… Credit: NASA/Goddard/Dana Berry©NASA's Goddard Space Flight Center

Known knowns about NSs
Some are rotation powered©Teruaki Enoto

Pulsar©NASA/CXC/ASU©NASA/CXC/INAF

Some are magnetically powered

Some are quasi-thermal

Central Compact Object

CCO©NASA/CXC/DSS

Some are accretion powered

X-ray binary
Magnetar©NASA/Goddard Space Flight Center• Known unknowns about NSs
How and when NSs are formed?
Supernova explosion mechanism?
How the trifurcation ofpulsar/magentar/CCO occurs?

?
?

How and when binary NSs are formed?
Ultraluminous X-ray pulsars?
Short gamma-ray bursts?

?

Particle acceleration & emission mechanism• Coherent radio emission?
• Magnetar flare?
• When an NS can be an FRB source?
• NSs are pevatrons?

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FRBs from a Galactic magnetar

FRB200428 from SGR 1935+2154 detected by CHIME (~kJy @ 400-800 MHz) and STARE2 (~Mega Jy @ 1.3GHz )P = 3.25 s
Ṗ = 1.4 ⇥ 10 11 s · s 1

Bd = 2.2 ⇥ 1014 G

The CHIME/FRB Collaboration et al. 20;
Bochenek et al.20

Won’t miss the next Galactic event!

GW

ν
EM

CR

Diversity in NS formation andassociated transients
Red supergiant
(RSG)

©4D2U

Blue supergiant(BSG)

Walf-Rayet star(WR)rotation, magnetic field,
pre-collapse mass eruption,
single or binary, …

Gal-Yam 12

Won’t miss especially the “on-axis” event!
©Kenta Kiuchi

GW

ν
EM

CR

NASA/ESA/Gaia/DPAC

Known knowns about BHs• Known unknowns about BH?
How and when (binary) BHs are formed?
Associated with energetic transients?

?

Mass and spin distribution?
Ultraluminous X-ray sources = intermediate BH?

?
tim
e

“Floating” BHs in the Galaxy
How are they?
Where they are?

Diversity in BH formation andassociated transients
Red supergiant(RSG)

slow rotation
Weak explosion

Intermediate rotation

Blue supergiant(BSG)

Walf-Rayet star(WR)

Fast rotation

NASA/Goddard Space Flight Center Conceptual Image Lab

CREDITS: NASA and A. Feild

How can be the jet launched and accelerated up to 99.99% of the speed of light?
How can be the energy dissipated to produce the most luminous emission in the Universe?

Diversity and universality of compact objects
Gravitational energy• Rotation• Magnetic field…
• Outflow/jet• Shock• Reconnection…

Multi-messenger signal

Compact objects as cosmic-ray accelerators©T. K. Gaisser?

Young Pulsars are Pevatrons?
Cao et al.21

SN/GRB/FRB cosmology

Ravi et al. 19©NASAkey questions of compact objects I
What kind of massive star (RSG, BSG, WR) produces
what kind of compact object (NS or BH? B field, rotation, disk?)
and what kind of explosive transient (SN, GRB or else) ?
Image credit: Chandra

key questions of compact objects II
What kind of compact binaries (BBH, BNS, BHNS, …) produces
what kind of compact object (NS or BH? B field, rotation, disk?)
and what kind of explosive transient (GRB, FRB, or else) ?
How compact binaries are formed?
Image credit: Chandra[NSF/LIGO/Sonoma State University/A. Simonnet]

Image credit: LIGO, NSF, A
urore Simonnet (Sonoma State U.)

Credit: NASA/Dana Berry, Sky Works Digitalkey questions of compact objects III
How (relativistic or non-relativistic) outflows are accelerated andhow is the energy converted to thermal and non-thermal emission?
What is the central engine? à mostly compact objects (BH, NS, WD)

NASA/Goddard Space Flight Center Conceptual Image Lab

Credit: NASA/CSC/SAO
CREDITS: NASA and A. Feild

So, what we do?
• Multi-messenger and time domain astronomy
à find transients as many as possible and characterize them with follow up observations• Deeper surveys/observations in multi-wavelengthà find and characterize Galactic compact objects as many as possible• New windows?

• e.g., sub-hr cadence optical surveys• space based GW detectors• MeV gamma rays
• X-ray polarization• …

c.f.,

Astro2020: Panel on Compact Objects andEnergetic Phenomena• … . Its scope will include white dwarfs; neutron stars; pulsars;
magnetars; stellar mass black holes; compact binary systems; novae;
supernovae; gamma-ray bursts; fast radio bursts; physical processes
and accretion onto supermassive black holes; and gravitationalradiation and high-energy particles and radiation from astrophysicalsources.

Q1: What are the mass and spin distributions ofneutron stars and stellar-mass black holes?
• Q1a: What do the mass and spin distributions tell us about neutronstar and black hole formation and evolution?
• Q1b: What is the population of noninteracting or isolated neutronstars and stellar-mass black holes?
• Q1c: What is the equation of state of ultradense matter?

Q2: What powers the diversity of explosive
phenomena across the electromagnetic spectrum?
• Q2a: When and how are transients powered by neutron stars or
black holes?
• Q2b: When and how are transients powered by shocks?
• Q2c: When and how are transients powered by radioactivity?
• Q2d: What are the unexplored frontiers in transient phenomena?

Q3: Why do some compact objects eject material
in nearly light-speed jets, and what is that material
made of?
• Q3a: How do jets launch and accelerate?
• Q3b: What are jets composed of and how are particles accelerated
within them?
• Q3c: Are TeV-PeV neutrinos and ultra-high- energy cosmic rays
produced in relativistic jets?

Q4: What seeds supermassive black holes
and how do they grow?
• Q4a: How are the seeds of supermassive black holes formed?
• Q4b: How do central black holes grow?

TABLE B.2 Required Capabilities
Current/
Expected
Facilities

Capability

Science EnabledRadio timedomain surveys

B-Q1: ms-PSR searches and
GBT, Arecibo,
timingCHIME, FAST,
B-Q2/DA: FRB searches; transient JVLA, SKA, anddetection
Pathfinders

Future Needs
Multipixel cameras for single-dishpulsar observations. Pulsar
search/timing backends for arrays.
Arcsec localization for transients.
Commensal FRB searches for all cmband observations.

High-angularB-Q2/DA: Transient follow-up
resolution
B-Q3: Jet formation, acceleration
radio/mm imaging and composition; particle
and polarimetry
acceleration
B-Q4: Accreting IMBHs; binary
AGN

JVLA,
MeerKAT,
GMRT, ATCA,
ALMA, VLBI,
EHT, SKA

Extremely high angular resolution (submas to µas). Polarimetry and Faraday
rotation.

O/IR time-domain B-Q1: Noninteracting binary or
surveysfree-floating NSs and BHs
B-Q2/DA: Transient detection;
pre-explosion imaging of SNe
B-Q4: TDEs in IMBHs; binary
AGN

ASAS-SN, ZTF,
Rubin/LSST,APOGEE, DESI,SDSS-V,ATLAS, Gaia,
TESS, WFIRST,
EuclidBroad range of cadences (hours toweeks) and sensitivities (magnitude 10–
24 in single images); prompt public
release.

Massively
multiplexed O/IR
spectroscopy

B-Q1: Noninteracting binary NSs APOGEE, DESI, Rapid response (<1 hr). Cadences ofand BHs
SDSS-V
hours to weeks. ELT-class sensitivity. R
B-Q2/DA: Transient follow-up~ 1000.

Deep O/IR line
spectroscopy

B-Q1: Radial velocity curves ofbinaries of interest
B-Q2/DA: Transient follow-up
B-Q4: redshift of high-z AGN

High-angularresolution O/IR
imaging andspectroscopy

B-Q3: Jet acceleration; particle
8–10 m-class<10 mas angular resolution and ELTacceleration
ground AO, HST, class sensitivity. Rapid response to
B-Q4: Dynamical confirmation of JWST, WFIRST transients. R ൐ 5000 for IMBH masses.
local IMBHs; binary SMBHs

UV imaging andspectroscopy

B-Q2/DA: Transient follow-up

Swift/UVOT,
HST

Comparable post-Swift and post-HST
coverage. Rapid response to transients.

Wide-field X-ray(0.5–100 keV)monitors

B-Q1: New NS/BH transients
B-Q2/DA: Transient detection

Swift/BAT,
MAXI,
Fermi/GBM,
eROSITA

Post-Swift and post-Fermi coverage.
Range of capabilities optimizing trades
between high sensitivity, wide-fieldcoverage, and <arcmin localization.

8–10 m-classground, HST,
JWST

ELT-class sensitivity. Rapid response totransients. R ~ 100 for classification, R~ 1000–5000 for follow-up and RVs.

X-ray imaging and B-Q1: NS/BH disk reflection lines Chandra, XMM,
spectroscopy
B-Q2/DA: Transient follow-up
NICER,
B-Q3: Jet spectroscopy
NuSTAR,XRISM, Athena

10-19 erg/cm2/s sensitivity and moderate(R ~ 100) spectral resolution. Hard Xray coverage (10–100 keV) with 10-14
erg/cm2/s sensitivity. Rapid response totransients.

X-ray spectral
timingPost-NICER/XMM coverage. <0.1 mstime resolution. Larger effective area(>1 m2 @ 1 keV; >4 m2 @ 10 keV).
High throughput.

B-Q1: NS/EOS pulse profile
modeling; pulsar timing
B-Q2/DA: Transient follow-up

XMM, NICER

Capability

Science Enabled

High-angularresolution X-ray
imaging

B-Q1: ULXs and other point
sources in nearby galaxies
B-Q2/DA: Transient follow-up
B-Q3: Jet acceleration, particle
acceleration
B-Q4: SMBH seeds

Current/
Expected
Facilities

Future Needs

Chandra, XMM, High angular resolution (<1 arcsec @1
NuSTAR, Athena keV; <15 arcsec @20 keV). Hard X-ray(>10 keV) coverage. 10ൈ
Chandra/NuSTAR sensitivity.

X-ray/gamma-ray B-Q3: Jet and disk orientation and INTEGRAL,
polarimetrygeometry
IXPE

10ൈ IXPE sensitivity. Soft X-ray and
MeV gamma-ray coverage.

MeV gamma-ray
line spectroscopy

B-Q2/DA: Nuclear lines from SNe INTEGRAL/SPI Wide (>1 sr) FOV. Sensitivity <8 ൈ 106
ph/cm2/s in 106 s for ~1 SN-Ia/yr
detected.

MeV/GeVgamma-ray
imagingFermi
B-Q1: Faint ms pulsars
B-Q2/Q3/DA: Transients;
counterparts for neutrino/UHECR
sources; GRB jet launch

TeV gamma-rays

B-Q3/DA: Counterparts for
HAWC, MAGIC, Post-HAWC/VERITAS coverage.
neutrino/UHECR jet sources, EM HESS,
sources; particle acceleration
VERITAS,LHAASO

Low-frequency(nHz/mHz)gravitationalwaves

B-Q1: NS and BH binaries
B-Q4: SMBH binaries
B-DA: GW counterparts of EM
sources

NANOGrav andother PTAs,
LISA

High-frequency(Hz/kHz)gravitationalwaves

B-Q1/Q3: NS and BH
mergers/jets
B-Q2: Transient detection
B-Q4: IMBH mass function
B-DA: GW counterparts of EM
sources

LIGO/Virgo,
BNS mergers to z ~ 10; 30/30 Mո BBH
KAGRA, LIGO- and IMBH mergers to z ~ 20.
India, LIGO/A+ Localization to <10 deg2.

MeV neutrinos

B-Q2/DA: SNe (including diffuse Super-K, Hyper- 10ൈ Hyper-K volume for ~1 SN/yr.
K
thermal background)

TeV/PeV/EeV
neutrinos

B-Q3: Jet
counterparts/composition
B-DA: ߥ counterparts of EM
sources; diffuse TeV/PeV
background

MeV coverage. Post-Fermi GeV
coverage.

Continued PTA coverage with larger
pulsar sample. Detect all merging
SMBHs, localize loudest to <10
arcmin2. Full U.S. access to LISA data.

IceCube,
ANTARES,KM3NeT

10ൈ IceCube volume for ~1 ߥ /yr fromTXS 0506-like transients. EeV
coverage.

Ultra-high-energy B-Q3: Jet(EeV) cosmic rays counterparts/composition
B-DA: UHECR counterparts ofneutrino and EM sources

Auger, TA,
LHAASOContinued coverage. 10ൈ larger
exposure. >4ൈ larger detector area.

Theory,computation, andsimulations

Broad support for theory and computation across all areas.
Next-generation computing for multidimensional radiationhydrodynamics and PIC simulations, numerical relativity.
Training for GPU-based computation. Advanced nuclear
reaction network, cosmic ray transport, and hadronic
cascade simulations.

B-Q1/Q2/Q3/Q4/DA