Effects of galactic interaction on the star formation efficiency and the diffuse gas

Neven Tomičić (INAF-OaPD)

INAF-OaPD: Daniela Bettoni, Marco Gullieuszik, Andrea Franchetto, Alessia Moretti, Bianca Poggianti, Benedetta Vulcani, ...

Kathryn Kreckel (MPIA), I-Ting Ho (MPIA), Eva Schinnerer (MPIA), Guillermo A. Blanc (Carnegie), Chris Faesi (MPIA), Santiago Garcia-Burillo (OAN), Brent Groves (ANU), Annie Hughes (CNRS, IRAP), Tom Jarret (Uni. Cape Town), Maria Kapala (Uni. Cape Town), Adam Leroy

(OSU), Rebecca McElroy (MPIA), Jerome Pety (IRAM), Miguel Querejeta (ESO), Florent Renaud (Lund Uni.), Toshiki Saito (MPIA), Karin Sandstrom (UCL), David Thilker (Johns Hopkins Uni.)

Trieste, 28.10.2019.

Neven.tomicic@inaf.itTomičić et al. 2017, ApJ 844:155

Tomičić et al. 2018, ApJL, 869, L38 Tomičić et al. 2019, ApJ, 873, 1

NGC2276 JO206

JO206

1st Postdoc, GASPObservatory in Padova, INAF

(Padova, Italy)

MUSE, VLT (ESO, Chile)

NGC 2276 JO206

The

Orio

n N

ebul

a.

Cre

dit:

Rob

bert

o, H

ST,

E

SA

, NA

SA

Stars

Interstellar medium (ISM)

Atomic neutral gas

Molecular gasDust

Atomic ionized gas

Collapse

Star forming region (HII region)

Formation

Fee

dbac

k

Kennicutt-Schmidt diagram

Fig. ΣSFR

vs. Σgas

(Kennicutt-Schmidt) diagram. Credit: Kennicutt & Evans 2012.

Star Formation Rate (SFR)

Kennicutt-Schmidt diagram

Fig. ΣSFR

vs. Σgas

(Kennicutt-Schmidt) diagram. Credit: Kennicutt & Evans 2012.

1) Star Formation Efficiency (SFE*) in interacting galaxies

SFE = 1/τdepletion =ΣSFR /Σgas

2) Effects of Diffuse emission

Star Formation Rate (SFR)

How does galactic interaction affects efficiency of SFR?

SFE = 1/τdepletion =ΣSFR /Σgas

1) Does SFE change through galactic evolution and interaction?

2) Mean galactic value vs. sub-galactic values?

τdepletion

≈ 2 Gyr

How does galactic interaction affects efficiency of SFR?

SFE = 1/τdepletion =ΣSFR /Σgas

1) Does SFE change through galactic evolution and interaction?

2) Mean galactic value vs. sub-galactic values?

τdepletion

≈ 2 Gyr

Fig: The Kennicut-Schmidt diagram of a pair of simulated interacting galaxies.

Credit: Renaud et al. 2014

Is molecular gas also assymetric?

NGC 2276:Asymmetric SFRsurface density

Asymmetric SFR

surface density

Symmetric molecular gas

surface density

Fig. Surface density of the SFR and the molecular gas, and the depletion

time of NGC 2276. Credit: Tomičić+18

Slit

Ram pressure?

Tidal force?

Fig. Kennicutt-Schmidt diagram of NGC 2276. Credit: Klaas et al. 2016; Saito et al. 2015,16; Tomičić+18

Extragalactic forces?

1) Spatial variation in SFE

2) Mean galactic valuevs.

3 orders of magnitude variation in SFE

3) Galactic evolution?

Slit

Ram pressure?

Tidal force?

Fig. Kennicutt-Schmidt diagram of NGC 2276. Credit: Klaas et al. 2016; Saito et al. 2015,16; Tomičić+18

Extragalactic forces?

1) Spatial variation in SFE

2) Mean galactic valuevs.

3 orders of magnitude variation in SFE

3) Galactic evolution?

Disk

Star Formation Efficency in the tails of stripped galaxies

(GASP survey)?

See the talk of A. Moretti

JO206

MUSE, VLT (ESO, Chile)

Diffuse ionised gas in tails

- fractions- effects on SFR and Metallicity- origin?

Fig: Jellyfish galaxy JW100, Hα,corr (B. Poggianti et al. 2017) and stellar disk (M. Gullieuszik et al. 2019).

Work in progress

Stellar

disk

M. GullieuszikB. Poggianti

Diffuse Ionised Medium (DIG)

Fig: Composite Hα intensity map; c. Finkbeiner+2003

Warm low density

Higher [SII]/Hα ratio

kpc scales (!!)

Sources: - HII regions- SN remnants- stellar winds - clumpy (fractal) ISM- scattering from the dust- CR

HII

DIG

Methods of quantifying:

Fig: Jellyfish galaxy JO206, Hα image with knots (HII regions) determined by Hα flux.

c. Poggianti+2016

Fig. Boundaries of HII regions determined the [SII]/Hα ratio.

c. Kreckel+2016

1) Hα flux 2) [SII]/Hα ratio

HII HII

DIGDIG

[SII]/Hα > 0.2

[SII]/Hα = 0.1

Metallicity?100%

0%

3) [SII]/Hα vs Hα,corr diagram

Fig: [SII]/Hα vs Hα,corr diagram to determine the fraction of the DIG.

c. Blanc+2009

DIG fraction

Non-Jellyfish galaxies.

Fig: Fitting [SII]/Hα vs Hα,corr diagram to determine the fraction of the DIG. Left- data corrected for gas metallicity variation (c. A. Franchetto). Right- observed [SII]/Hα values, with lines of the fit varied by gas metallicities.

c. Tomicic+in prep.

A. Franchetto

Fig: Left- Hα,corr map with HII knots. Right- estimated DIG fraction.c. Tomicic+in prep.

Non-Jellyfish galaxies.

How reliable are methods that use only the [SII]/Hα ratio or using only the Hα emission?

Next steps:

- How different Tails from Disks are?- Fraction of DIG among the Jellyfish galaxies- origin of the DIG?

Thank you!

Fig: Stellar mass distribution (color) and

observed Hα (contours). Credit: Tomičić+18

Ram pressureTidal force

Fig: Stellar mass distribution (color) and observed Hα (contours).

Credit: Tomičić+18

Fig: Proxy for an age of the stellar clusters. Credit: Tomičić+18

Recent

Older

BOTH forces acting on the

galaxy?