Star formation & physical processes in Sculptor Group galaxies at low radio frequencies
Anna D. Kapinska ICRAR, The University of Western Australia A quick intro & overview
A detailed study of a bunch of local well-studied galaxies → near-by & resolved
Broadband radio SEDs: 70 MHz – 11 GHz → modelling of the underlying physical processes
2 A.D. Kapinska: SF at radio frequencies A quick intro & overview
A detailed study of a bunch of local well-studied galaxies → near-by & resolved
Broadband radio SEDs: 70 MHz – 11 GHz → modelling of the underlying physical processes
Crucial: data from the Murchison Widefiled Array (MWA)
GLEAM DR1: 70–230 MHz
(Hurley-Walker+2017)
3 A.D. Kapinska: SF at radio frequencies Local starburst and star-forming galaxies NGC 7793
Sculptor Group ➢ loose association, 2 – 4 Mpc away ➢ close so great laboratory for detailed study
NGC 7793 NGC 300 NGC625 NGC 300
CTIO GALEX GALEX
NGC 253 NGC 55 NGC 247
ESO Gendler ESO 4 A.D. Kapinska: SF at radio frequencies Local starburst and star-forming galaxies NGC 7793
Sculptor Group ➢ loose association, 2 – 4 Mpc away ➢ close so great laboratory for detailed study
NGC 7793 NGC 300 NGC625 NGC 300
CTIO GALEX GALEX
NGC 253 NGC 55 NGC 247
ESO Gendler ESO 5 A.D. Kapinska: SF at radio frequencies NGC 253 (Sculptor galaxy)
Kapinska+ 2017a
TGSS+GLEAM 150MHz Credits: Staveley-Smith, Kapinska
6 A.D. Kapinska: SF at radio frequencies NGC 253 (Sculptor galaxy)
MWA
TGSS
Kapinska+ 2017a
TGSS+GLEAM 150MHz Credits: Staveley-Smith, Kapinska
7 A.D. Kapinska: SF at radio frequencies Broadband radio SED of NGC253
MWA
TGSS
Kapinska+ 2017a
8 A.D. Kapinska: SF at radio frequencies Physical processes at radio frequencies
→ mainly SNR, also disk winds, jets from → HII regions, X-ray binaries etc ionised medium
9 A.D. Kapinska: SF at radio frequencies Modelling radio SED of NGC 253
Total
200 MHz – 1.46 GHz
Central starburst region Turnover frequency ~230 MHz Disk and halo Kapinska+ 2017a → emissivity 4x 105 pc/cm6
10 A.D. Kapinska: SF at radio frequencies Synchrotron radio halo of NGC 253
HI (KAT-7; Lucero+2015) Xrays (0.5-1 keV; Bauer+2008)
200 MHz – 1.46 GHz
Central starburst region Disk and halo Kapinska+ 2017a
11 A.D. Kapinska: SF at radio frequencies Other detections of Sculptor Group galaxies
NGC 300
NGC 55
NGC 7793
A.D. Kapinska: SF at radio frequencies Other detections of Sculptor Group galaxies
NGC 300
Kapinska+ 2017c (almost finished)
Galvin+ 2014
cf. Condon 1987
A.D. Kapinska: SF at radio frequencies Radio SEDs of Sculptor Group galaxies
Kapinska+ 2017c to be subm.
14 A.D. Kapinska: SF at radio frequencies Radio SEDs of Sculptor Group galaxies
Synchrotron Synchrotron
Thermal
Kapinska+ 2017c Turn-over? to be subm.
15 A.D. Kapinska: SF at radio frequencies Radio SEDs of Sculptor Group galaxies
Synchrotron Synchrotron
Thermal
Kapinska+ 2017c Turn-over? to be subm.
16 A.D. Kapinska: SF at radio frequencies Radio SEDs of Sculptor Group galaxies
SEDs show variety of shapes 1) Radio → SF tracer.. 2) detectability @radio
Kapinska+ 2017c to be subm.
17 A.D. Kapinska: SF at radio frequencies Tracing star formation with radio
FIR/radio correlation
Grey – Yun+ 2001
Also for radio-quiet AGN!! → Wong+ 2016
Kapinska+ 2017c to be subm.
18 A.D. Kapinska: SF at radio frequencies Tracing star formation with radio
FIR/radio correlation
similar: Callistro-Rivera+ 2017 (150MHz)
Cyan – scaled
Kapinska+ 2017c to be subm.
19 A.D. Kapinska: SF at radio frequencies Tracing star formation with radio
FIR/radio correlation
similar: Callistro-Rivera+ 2017 (150MHz)
Cyan – scaled
Grey – Yun+ 2001
Also for radio-quiet AGN!! → Wong+ 2016
Kapinska+ 2017c to be subm.
20 A.D. Kapinska: SF at radio frequencies Summary
– Star formation @ radio frequencies still poorly understood, need more study of broadband radio SEDs (MHz ↔ GHz)
– Much more to it than just sum of HII regions and SNRs
– FIR/radio correlation at MHz radio frequencies better than at 1.4GHz?
21 A.D. Kapinska: SF at radio frequencies