Latest impacts of observational (radio) astronomy

Hiroshi ImaiDepartment of Physics and Astronomy

Graduate School of Science and Engineering

Introducing “Nature” and “Science” papers Latest impacts of radio astronomy (HI’s favorites)

stars: classification, formation, and evolution extra-planets interstellar medium the Milky Way Galaxy cosmology

“Nature” and “Science” journalsWhich kind of result has a deep impact published in

these papers in astronomy?• amazing and/or important topic to researchers

and the public– unexpected discovery– solving long-standing (debating) issue

• Type of impacts– finding new phenomenon, classification– developing new technique– implication to new possibility

“Nature” and “Science” journals

What is currently hot topics in (radio) astronomy?• New type of radio sources (e.g. fast radio bursts)• Newly found phase of

star formation and stellar evolution• Newly discovered gas dynamics• New characteristics of a black hole,

a high-envergy object, and interstellar medium

• Innovative research technique• Deeper exploration of early universe

Note: not all important works were published in these major journals.

Galactic and extragalactic astronomy• Targets with known and unknown distances• Nearest targets in the universe and others• Individual stars and unresolved star clusters• Present (red shift z~0) and past universe

M31D=800 kpcUnresolved star clusters

LMCD=50 kpcresolved into individual stars

Gas fragmentation• Dendrogram identification of

hierarchical structures of gas clumps• Visualization of the process of

gas clump fragmentation• Lower limit to

self-gravitating clumps of 0.2 pc

Goodman et al. 2009

Gas inflow through a gap of a proto-planetary disk

ALMA Cycle-0•CO emission: disk rotation•Inner HCO+:gas inflow(7×10-8Msun yr-1)

HD152527 (Cassassus et al., 2013, Nature, 493, 191)

Mass infall onto a massive young stellar object• identification of a ~20 Msun young stellar object• outflow, rotation, and infall (Betran et al. 2006)

Contraction for massive star formation• Gas toroid mass ~87 Msun

• Magneto-hydrodynamically super-critical contraction

(Girat et al. 2009)

A large coronal loop in Argol

Peterson et al., 2010, Nature, 463, 207

High-precision astrometry to trace stars’ positions

A large coronal loop in Argol

Peterson et al., 2010, Nature, 463, 207

• First direct radio imaging of a coronal loop except the Sun• Giant “dynamo” created by rapidly rotating binary stars

Spiral pattern of mass-loss flow

ALMA CO J=32 emission observation toward R Sculptoris(Maercker et al. 2012, Nature, 490, 232)

• Spiral pattern created by binary stars

• Unexpectedly large stellar mass loss during a thermal pulse

(for 200 years, 1800 years ago)

Sgr A*: the nearest super-massive blackholeGilessen et al. 2009; Ghez et al. 2008• Mass density: 108Msunpc-3

• Movement of the apoastron• Distance to the Galactic center:

R0=8.33±0.35 kpc

◎

Sgr A* spatially resolved?• 1AU in size at λ=3.5 mm Shen et al. 2005• “Event horizon scale” resolved at λ=1.3 mm?

Doeleman et al. (2008)

3.5 mm 3.5 mm uniform weighting super-resolution

1.3 mm visibility plot

G2 clouds: passing periastron of Sgr A* in 2014?

See ESO movie

Gillessen et al. 2012

See also http://www.eso.org/public/videos/

Rotation measure for PSR J1745-2900 (0.12 pc from Sgr A*)

Eatough et al., 2013, Nature, 501, 391

Strong magnetic field nearby Sgr A*

B~2.6 mG at r~0.12 pc Enough magnetic flux accreted onto the event horizon to explain electro-magnetic emission flux from BH at Sgr A*

Eatough et al., 2013, Nature, 501, 391

Giant magnetized outflows from the center of the Milky Way

Magnetic energy transfer (1047 J) from the star formation sites (within 200 pc from the Galactic center) to the Galactic halo

Carretti et al. 2013, Nature, 493, 66

(VLA+WMAP)

Exact position of a super massive black hole

Image courtesy of NRAO/AUI and Y.Y. Kovarev, MPIfR and ASC Lebedev

“Core shift” technique

• Optical thickness dependent on radio frequency

• Very close to a high-frequency radio core

• Wide opening angle of the jet in M87

Hada et al. 2011, Nature, 477, 185

Nature Breaking News on 17 March 2014

B-mode in cosmic microwave backgroundsub-millimeter polarimetric measurement

B-mode in cosmic microwave background

Nature Breaking News on 17 March 2014Using South Pole Telescope

Fundamental constants dependent on location?

Lab. and VLA measurements (Truppe et al. 2013, Nature, open access)

Fine structure constant αElectron-proton mass ratio Δμ/μ

Fast Radio Bursts (FRBs)New type of transient radio sources

• milli-second radio flares (FRB110220, 110627, 110703, 120127)

• Extremely large dispersion measures

• Likely located at cosmological distance (z>0.5)SνD~1012Jy kpc2

E~1032JThornton et al. 2013, Science, 341, 53

Enjoy astronomical discoveries with understanding

backgrounds and implications!

Report

Describe which kind of “virtual” scientific theme is expected to appear in the major journals such as “Nature” and “Science”. Also show why you consider so by describing the following points.

1.Current background2.Imagined new results3.Implication of the results