High Angular Resolution High Angular Resolution Radio Observations of Radio Observations of

(U-)LIRGs(U-)LIRGs

Antxon Alberdi (IAA, CSIC)

(+ M.A. Pérez-Torres, C. Romero-Cañizales,R. Herrero-Illana + J. Conway +

R Beswick + M Bondi + ST Garrington + TWB Muxlow …)

RTS – “Resolving the Sky …”

Manchester, 19 April 2012

1010 – 1011 Msun

SFR < 2 Msun yr-1 (e.g., the Milky

Way)

SFR ~ 10-100 Msun

yr-1

t ~ 109-10 yr t ~ 107-8 yr < galaxy lifetime

starburst

Starburst GalaxiesStarburst Galaxies

Typical SFRs are a few x10-100 Msun/yr CCSN rates a few x

(0.1-1) SNe/yr

ULIRGsLIRGs

• LIR > 1012 Lsun

• z~2 (Caputi (Caputi +07)+07)

• LIR > 1011 Lsun

• z~1 (Le Floc’h (Le Floc’h +05)+05)

(U)LIRGs: scaled up starbursts(U)LIRGs: scaled up starbursts

(Magnelli (Magnelli et al., et al., 2009)2009)

z

- Significant fraction of the SF at high-z took place in (U-)LIRGs

- Detection of SNe crucial for revising CCSN rates both locally and at high-z

Mrk 331(D = 77 Mpc)

NGC 1614(D = 50 Mpc)

Radio Observations of Starburst Galaxies

Compact (≤150 pc) high surface brightness (T b ≥ 103 K) central radio source generated by a point-like source (AGN) and/or by the combined effect of SNe and RSNe

Low surface brightness circumnuclear halo ongoing burst of star formation

Scientific casesScientific cases

Arp299 at 45 Mpc, LIR ~ 6.7 x 1011 Lsun

NGC 7469 at 70 Mpc, LIR ~ 5 x 1011 L sun

IC883 at 100 Mpc, LIR ~ 4.7 x 1011 Lsun

IRAS 23365+3604 at 252 Mpc, LIR ~ 1.4 x 1012 Lsun

Early stage merger

D ~ 45 Mpc 1 mas ~ 0.2 pc

LIR ~ 6.7 x 1011 Lsun

~ 40% in A

~ 20% in B1

HSTHST - -WFPC2WFPC2 814nm image (Neff et al., 2004) 814nm image (Neff et al., 2004)

Arp299Arp299

1

IC694

NGC3690

νCCSN ≈ 0.8 yr-1

νCCSN ≈ 0.4yr-1

Stacking of the 6-epochs of (e)EVN images

(April 2008 through Nov 2010)

Bondi et al (A&A, 2012)

- 26 sources detected- 8 new ones- Mixed population of

CCSNe and SNRs- Evidence for at least

2 recent SNe- CCSN ~ 0.8 SN/yr- Taking into account

the other 2 SNe that exploded in 2010 => uncomfortably large CCSN rate for Arp 299-A => Top heavy IMF!?

rms = 18.5 microJy/b

The Arp 299-A lab: The Arp 299-A lab: SummarySummary

The AGN-SB connection in Arp 299A

Pérez-Torres+2010 (Letters to A&A)

• A1-A5 complex identified with the long-sought AGN (A1-core; A5-jet)

• Ratio of (5 GHz*L_5)/L_X => LLAGN

• A0 - A RSN just 2 pc away from a SMBH!!

• Is SB activity hindering BH accretion, and thus => LLAGN!?

A

Arp 299: eMERLIN Arp 299: eMERLIN ImageImage

- A highly luminous infrared, QSO-like, galaxy;

- It interacted with IC 5283 more than 1.5 x 108 yrs ago;

- There is evidence for a 107 Msun BH;

- D ~ 70 Mpc 1 mas ~ 0.32 pc

LIR ~ 5 x 1011 Lsun

NGC7469 @ 1.6NGC7469 @ 1.6μμmm (Alonso-Herrero et al., (Alonso-Herrero et al., 2004)2004)

NGC 7469NGC 7469

1

νCCSN ≈ 0. 82 yr-1

SN 2000ft in NGC 7469

Colina et al. ApJ 553, L19 (2001); Alberdi et al. (2006); Pérez-Torres et al. (2009)

SN 2000ft is located in the circumnuclear ring (1 kpc), at a distance of 600 pc of the nucleus;

L SN2000ft = 1.1 x 10 21 W/Hz, very luminous;

Fitting parameters are typical of type-II radio supernovae;

Mass loss rate ≤ (4.7-5.1) x 10-5 M sun / yr, typical of a RSG-progenitor

R1R2

R3

SN2000ft

NGC NGC 74697469

Pérez-Torres et al. 2009, MNRAS 399,

1641;Alberdi et al. 2012

Structure Variability of the nucleus of NGC 7469 at λ 6cm

Alberdi et al. 2012

Radio spectrum of

the nucleus of NGC 7469

Alberdi et al. 2012

Spectral index map

The nuclear region of NGC 7469

A B C D

C1: AGN (L = 3×1038 erg/s) flux density/structural variability;

C2: rather compact + flux density variability + -variable;

C3: very compact (θ<3mas; TB>5×106 K) + quite steady in flux + (~0.5) Long-lasting SNR candidate?

C4: flux density variability; compact source within extended flux (~1).

C4 C3 C2

C1

IC883IC883Romero-Cañizales et al., 2012, (A&A, Romero-Cañizales et al., 2012, (A&A,

submitted)submitted)

Advanced stage merger (starburst-AGN composite)

D ~ 100 Mpc 1 mas ~ 0.5 pc

LIR ~ 4.7 x 1011 Lsun

ν CCSN ≈ 2.4 yr-1

Two new SNe discovered: SN 2010cu (Ryder et al., 2010) & SN 2011hi (Kankaré et al. 2011)

ν CCSN ≈ 2-1.3+2.6yr-1

HSTHST - -NICMOSNICMOS 1.6 μm image (Haan et al., 2011) 1.6 μm image (Haan et al., 2011)

IC 883: e-MERLIN + e-EVN observationsIC 883: e-MERLIN + e-EVN observations

~ 1 kpc structure at 144o, showing components of a warped rotating ring

Romero-Cañizales et al., 2012, Romero-Cañizales et al., 2012, (A&A, submitted)(A&A, submitted)

IC 883: e-MERLIN + e-EVN observationsIC 883: e-MERLIN + e-EVN observations

IC 883: ResultsIC 883: Results

AGNAGN & & SBSB together together

A1 (e-EVN) and A (e-MERLIN) AGN AGN

A2, A3, A4 … non-thermal compact components in a 100 x 100 pc region CCSNe candidates

The EVN ULIRG sample: IRAS 23365+3604The EVN ULIRG sample: IRAS 23365+3604

Advanced stage merger (starburst-AGN composite)

D ~ 252 Mpc 1 mas ~ 1.2 pc

LIR ~ 1.4 x 1012 Lsun

Farrah et al., 2003Farrah et al., 2003: AGN contributes with 35% to LIR νSN ≈ 2.4 yr-1

HSTHST - -NICMOSNICMOS 1.6 μm image (Haan et al., 2011) 1.6 μm image (Haan et al., 2011)

Romero-Cañizales et al., 2012 (MNRAS)Romero-Cañizales et al., 2012 (MNRAS)

IRAS 23365+3604: 6/18cm EVN IRAS 23365+3604: 6/18cm EVN observations observations

2010

20092008

26 x 38 mas, 46o

L-band area (200pc) > C-band area (100pc) L-band area (200pc) > C-band area (100pc) ee-- lifetime lifetime

Evidence for a Evidence for a nuclear starburst/AGNnuclear starburst/AGN

60 pc 60 pc

Romero-Cañizales et al., 2012 (MNRAS)Romero-Cañizales et al., 2012 (MNRAS)

IRAS 23365+3604: ResultsIRAS 23365+3604: Results

longer lifetime of elonger lifetime of e-- emitting at emitting at lower frequencies lower frequencies (L-band vs. C-(L-band vs. C-band emission occupies a larger band emission occupies a larger extension)extension)

different populations of radio different populations of radio emittersemitters (peak component at L- and C-bands do not coincide)

Ongoing nuclear activity, e.g., Ongoing nuclear activity, e.g., SNe and AGN SNe and AGN (Peak variable in position and intensity through time source variability within the nuclear region and/or appearance of new sources) Romero-Cañizales et al., 2012 (MNRAS)Romero-Cañizales et al., 2012 (MNRAS)

IRAS 23365+3604: IRAS 23365+3604: Spectral index (pixel-to-pixel)

Ongoing nuclear activity - SNe Ongoing nuclear activity - SNe and AGN and AGN ( α evolution)

Presence of old radio Presence of old radio emitters at the edges of the emitters at the edges of the nuclear region - SNRs nuclear region - SNRs (α distribution)

Magnetic Field in the nuclear Magnetic Field in the nuclear region (~175 region (~175 μμG) G) typical of typical of advanced mergersadvanced mergers

SummarySummary

Radio observations of (U)LIRGs at the highest resolution and sensitivity are extremely useful to: (i) discern SB from AGN driven activity in the innermost regions; (ii) determine their CCSN rate; and (iii) test the IMF of the massive stars.

VLBI radio searches on large samples needed to get meaningful statistical results (=> LIRGI: It will allow to establish a phenomenological sequence and timescale for the evolution of a nuclear starburst for a statistically significant sample of (U)LIRGs in the local universe ).

Thanks to …Thanks to …

JIVE-Staff for all the support along these years

EVN, for the improving quality of the data (eEVN, network session experiments …)

We are the USERS, another “essential” ingredient for these facilities (we have benefitted from research funding from the European Community FP7 and FP6)

European Radio Telescope Review Committee (ERTRC)

The ERTRC is appointed by the ASTRONET Board in coordination with RadioNet.

Its remit is to deliver to ASTRONET, and in concert with RadioNet, a strategy to optimize the use of radio telescopes by the European astronomical community, both in the short- as well as in the medium- to long-term.

Special attention should be paid to develop this strategy in close interaction with the telescope owners and with extensive feedback from the community at large.

Information and Discussion Forum athttp://ertrc.strw.leidenuniv.nl