ALMA Observations of Gas-rich Galaxies in z~1.6 Galaxy Clusters: - - PowerPoint PPT Presentation

ALMA Observations of Gas-rich Galaxies in z~1.6 Galaxy Clusters:

Evidence for Higher Gas Fractions in High-Density Environments

Mike McDonald, Adam Muzzin, Julie Nantais, Greg Rudnick, Eelco van Kampen, Tracy Webb, Gillian Wilson, Howard Yee, and the SpARCS Collaboration

J0225−541

1′′

HST 160 ALMA CO (2−1)

5′′

−0.20 0.00 0.20 0.40 0.60

J0224−396 J0224−424

1′′

HST 105 140 160 ALMA CO (2−1)

5′′

−0.20 0.00 0.20 0.40 0.60 Jy beam−1 km s−1

Allison G. Noble

Noble et al. 2017, ApJL, 842, 21 arXiv:1705.03062

Breakthroughs in Galaxy Evolution

Decline in cosmic star formation rate density

Madau & Dickinson 2014

Redshift log ψ (M year–1 Mpc–3)

–0.4 –0.8 –1.2 –1.6 –2 –2.40 1 2 3 4 5 6 7 8

Lookback time (Gyr)

2 4 6 8 10 12

c

Whitaker et al. 2014

Existence of star-forming main sequence

What drives these trends?

Breakthroughs in Galaxy Evolution

Decline in cosmic molecular gas mass density

Decarli et al. 2017

Dependence on star-forming main sequence

credit: A. Saintonge

Gas Regulation

Evolution of Molecular Gas in the Field

1 2 3 redshift

COLD GASS

(e.g. Saintonge+2011, 2012; Kauffmann+ 2012)

FCRAO Extragalactic CO

(e.g. Young+1995)

PHIBSS 1/2

(e.g. Tacconi+2010, 2013, 2017)

Lensed Galaxies

(e.g. Baker+2004; Coppin +2007; Saintonge+2013)

SMGs

(e.g. Reichers+2011; Hodge+2012)

IRAM FCRAO VLA

PEP

(e.g. Magnelli+2012)

Evolution of Molecular Gas in Clusters

1 2 3 redshift

Protoclusters

Aravena+2012 Wagg+2012 Casasola+2013

z < 0.5 1 < z < 1.5 N~100 N = 4 missing CO in massive clusters at z>1.5

Mok+2016 Geach+2011 Jablonka+2013 Cybulski+2016 Boselli+2014 Fumagalli+2009 Scott+2013 Stark+1986 Kenney&Young 1989 Casoli+1991 Boselli+1997

N ~15

…until this year (e.g. Noble+2017; Rudnick+2017; Hayashi+2017; Stach+2017)

Ivison+2013 Hodge+2013 Tadaki+2014 Dannerbauer+2017 Emonts+2013 Ivison+2012 Chapman+2015 Tan+2014

Walter+2012 Riechers+2010

Why z >1.5 clusters?

Nantais et al. 2016 van der Burg et al. 2014 Balogh et al. 2016

10.0 10.5 11.0 11.5 0.0 0.2 0.4 0.6 0.8 1.0 10.0 10.5 11.0 11.5 Log Mstellar (MO

• )

0.0 0.2 0.4 0.6 0.8 1.0 Passive Fraction 10.0 10.5 11.0 11.5 0.0 0.2 0.4 0.6 0.8 1.0 10.0 10.5 11.0 11.5 Log Mstellar (MO

• )

0.0 0.2 0.4 0.6 0.8 1.0 Passive Fraction

z∼0

10.0 10.5 11.0 11.5 0.0 0.2 0.4 0.6 0.8 1.0 10.0 10.5 11.0 11.5 Log Mstellar (MO

• )

0.0 0.2 0.4 0.6 0.8 1.0 Passive Fraction

z∼0 z∼1

10.0 10.5 11.0 11.5 0.0 0.2 0.4 0.6 0.8 1.0 10.0 10.5 11.0 11.5 Log Mstellar (MO

• )

0.0 0.2 0.4 0.6 0.8 1.0 Passive Fraction

z∼1.6 z∼0 z∼1

3 SpARCS Clusters at z~1.6

Nantais et al. 2016

• ~115 spectroscopically confirmed cluster members
• richness-based masses >1014 M⊙
• 11-band photometry for stellar masses (ugrizYK[3.6][4.5][5.0][8.0])
• MIPS and Herschel-imaging (24/250/350/500 um) for infrared-SFRs

4’ gz[3.6]

ALMA CO (2-1) Observations

13 hours of ALMA time (PI Noble) for 3 z~1.6 SpARCS clusters to detect CO 2-1

CO (2-1) detection in z~1.6 cluster galaxy! 88.23 GHz, 100 km/s channel beam ~ 4.4” x 2.2”

Noble et al 2017

rms ~ 0.17 mJy/beam in 100 km/s

2 pointings (FOV~110”) per cluster, encompassing 49 known spectroscopically-confirmed cluster members 11 CO (2-1) detections with S/N > 5 in z~1.6 cluster galaxies

110”

ALMA CO (2-1) Observations

Noble et al. 2017

30” x 30” CO Moment 0 6” x 6” HST Close pairs

SFR - M Plane

Noble et al. 2017

1010 1011 10 100 1010 1011 Mstellar (MO

• )

10 100 SFR (MO

• yr-1)

z ∼ 1.6 cluster CO detections pair galaxies

MS at z=1.6

see Saintonge et al. 2011, 2016; Genzel et al. 2015 Main Sequence at fixed z

Star Formation Rate Mstellar

lower SFE lower gas fraction higher SFE higher gas fraction

1010 1011 10 100 1010 1011 Mstellar (MO

• )

10 100 SFR (MO

• yr-1)

z ∼ 1.6 cluster CO detections pair galaxies

0.3 0.4 0.5 0.6 0.7 0.8 Gas Fraction

fgas = Mgas / (Mgas + Mstellar)

0.0 0.2 0.4 0.6 0.8 −1 1 2 3 0.0 0.2 0.4 0.6 0.8 fgas = Mgas / (Mgas+Mstellar) −1 1 2 3 (SFR − SFRMS) / SFRMS

log Mstellar = 10.9 scaling relation,

0.0 0.2 0.4 0.6 0.8 −1 1 2 3 0.0 0.2 0.4 0.6 0.8 fgas = Mgas / (Mgas+Mstellar) −1 1 2 3 (SFR − SFRMS) / SFRMS

log Mstellar = 10.9 scaling relation,

0.0 0.2 0.4 0.6 0.8 −1 1 2 3 0.0 0.2 0.4 0.6 0.8 fgas = Mgas / (Mgas+Mstellar) −1 1 2 3 (SFR − SFRMS) / SFRMS 0.0 0.2 0.4 0.6 0.8 −1 1 2 3 0.0 0.2 0.4 0.6 0.8 fgas = Mgas / (Mgas+Mstellar) −1 1 2 3 (SFR − SFRMS) / SFRMS

log Mstellar = 10.9 scaling relation, l

• g

Mstellar = 1 1 . 2 log Mstellar = 10.0

0.0 0.2 0.4 0.6 0.8 −1 1 2 3 0.0 0.2 0.4 0.6 0.8 fgas = Mgas / (Mgas+Mstellar) −1 1 2 3 (SFR − SFRMS) / SFRMS

log Mstellar = 10.9 scaling relation, l

• g

Mstellar = 1 1 . 2 log Mstellar = 10.0

cluster detections

10.0 10.2 10.4 10.6 10.8 11.0 11.2 log (Mstellar)

field at z=1.6 (Genzel+2015)

z~1.6 cluster galaxies are at systematically higher gas fractions (4σ) than the field

Gas Fractions in z~1.6 Cluster Galaxies

Mmol = αCO x LCO clusters require different conversion between CO and H2 from field?

see e.g., Bolatto et al. 2013; Narayanan et al. 2012 Noble et al. 2017

Conclusions

• 11 CO (2-1) detections in z~1.6 SpARCS clusters
• evidence for systematically higher gas fractions in SpARCS

clusters compared to the field scaling relations at z~1.6

• clusters require different conversion between CO and H2

from field?

• high cluster-to-cluster variation
• high-z clusters look to be exciting prospects for detecting gas-

rich galaxies

• need more CO observations!

Thank You!