Spatially-resolved galaxy angular momentum Sarah Sweet Swinburne With Deanne Fisher, Karl Glazebrook (Swin), Danail Obreschkow, Claudia Lagos, Liang Wang (UWA)
Outline • Background: – Angular momentum is fundamental – Measuring spatially-resolved angular momentum • Results: – The pseudobulge evolutionary track – Angular momentum at cosmic noon – The probability density function of angular momentum
Galaxy evolution
Galaxy evolution in context cosmic dawn cosmic noon cosmic evening NAOJ
Galaxy evolution in context GiggleZ
Galaxy evolution in context medium.com
Angular momentum is fundamental “Most astronomers would agree that the list of important parameters should be headed by the total mass M, energy E and angular momentum J. Next on the list should probably be the relative contributions to these quantities from the disk and bulge components…” (Fall 1983)
Angular momentum is fundamental • size • density evolution • disk thickness • colour • morphology Mo+1998, Hernandez+Cervantes-Sodi 2006, Fall 1983, Romanowsky+Fall 2012, Obreschkow+Glazebrook 2014, Cortese+2016, Posti+2018, Sweet+2018, Fall+Romanowsky 2018
Stellar mass is also fundamental • Remove stellar mass scaling
j baryons ~ j halo • same tidal forces during spinup • "angular momentum catastrophe” Fall 1983 Catelan+Theuns 1996a,b; van den Bosch + 2001; Barnes+Efstathiou 1987 Governato+2010, Agertz+2011
j baryons • more observable than j halo • tracers: j * , j Ha , j HI , j H2 • each with their own kinematics and mass profiles.
Angular momentum, stellar mass and morphology • q depends on Hubble type • ! ~ 2/3 • hierarchical Universe • Larger and later galaxies have higher specific angular momentum. Fall 1983, Romanowsky+Fall 2012
Angular momentum, stellar mass and morphology • 3D fit: – prefactor depends on B/T • ! ~ 1 – disk stability Obreschkow+Glazebrook 2014
Angular momentum, stellar mass and morphology • ! ~ 1 • motivates this projection • Galaxies with bigger bulges have lower specific angular momentum per unit mass. B/T • B/T < 0.32 Obreschkow+Glazebrook 2014
Bulge type • pseudobulges – rotationally-supported – secular evolution • classical bulges – pressure-supported – minor mergers or disk instabilities • Galaxies with classical bulges are more likely to have high bulge fraction than galaxies with pseudobulges Toomre1977, Schweizer1990, Toomre1964 Kormendy+Kennicut2004, Wyse+1997 Fisher+Drory2016 Buta2011
Cosmic noon galaxies • clumpy • high gas fractions • high rates of star formation • enhanced turbulence • predicted lower j/M • alpha~2/3? Glazebrook+1995b; Driver+1995; Abraham+1996a,b; Conselice+2000; Elmegreen+2005; Daddi+2010; Tacconi+2013; Bell+2005; Juneau+2005; Swinbank+2009; Genzel+2011; F ̈ orster Schreiber+2009; Wisnioski+2011; Wuyts+2012; Fisher+2014; Buta2011 Lagos+2017; Teklu+2015; Obreschkow+15
Local analogues • gain surface • brightness and spatial resolution • are they truly representative of high-z galaxies? Fisher+2017b
Baryons vs. haloes • j baryons ~ j halo but • baryons subject to more space.com physics – feedback – tidal stripping PDF(j) APOD j/j mean Catelan+Theuns1996; van den Bosch+2001; Sharma+Steinmetz2005
Open questions
Open questions • Does the M * – j * – B/T relation extend to high bulge fraction? Does it hold for classical bulges as well as for pseudobulge galaxies? • What is the AM of high-z disks? Does it match that of normal local disks? Does it match that of "local analogues"? What does that imply about their evolution? • Can the distribution of j be used as a tracer of evolutionary processes? As a tracer of morphology? As a kinematic decomposition tool?
Spatially resolving galaxies
Spatially resolving galaxies • Galaxies are not all smooth, exponential disks • Single-fibre and long-slit observations miss key structure
Integral field spectroscopy • A spectrum at every pixel; an image at every wavelength ifs.wikidot.com
Integral field spectroscopy • Advantages: – mitigating kinematic misalignment – accounting for structure in the disk • Disadvantages: – observationally expensive Sweet+2016; Cecil+2015; Obreschkow+2015
Integral field spectroscopic samples • THINGS: The HI Nearby Galaxy Survey • Romanowsky+Fall 2012 • CALIFA: Calar Alto Legacy Integral Field Area • KGES: KMOS Galaxy Evolution Survey at z~1.5 in COSMOS, CDFS and UDS • DYNAMO: clumpy, star-forming z~0.1 galaxies Walter+08; Leroy+08; Romanowsky+Fall12; Falcon-Barroso+17; Mendez-Abreu+17; Tiley+ip; Green+10,14
Measuring angular momentum
Measuring angular momentum: objectives • minimise beam-smearing – need adaptive optics- assisted observations • trace the bulk of j – need natural seeing data • extrapolate to r= ∞ – need model estimate Sweet+2018,2019
Measuring angular momentum: details 1. measure spaxel-wise angular momentum separately for the adaptive optics and seeing-limited kinematic data 2. calculate spaxel-wise model angular momentum – consistent with observed to 5% 3. mean j=J/M is calculated by integrating over a combination of 1) and 2) based on S/N AO contributes in inner regions (69%) • seeing-limited in outer regions (18%) • model contributes elsewhere (13%) •
Our best practice advantages • minimise beam-smearing • trace bulk of j • trace spatial variation in disk – order-of-magnitude improvement Obreschkow + Glazebrook 2014
Angular momentum & bulges Does the M * – j * – B/T relation extend to high bulge fraction? Does it hold for classical bulges as well as for pseudobulge galaxies?
Angular momentum & bulges • Sweet, Fisher, Glazebrook +: 2018ApJ...860...37S • tracing M * – j * – B/T over wide range of B/T, and accounting for bulge type • sample: THINGS, RF12, CALIFA • seeing-limited + model approach
Mass—angular momentum—bulge fraction • 2D fit: alpha = 0.56 +- 0.06 • Agrees with previous even 4.0 though: THINGS – different bulge-disk ● RF12 ● CALIFA ● ● decomposition methods ● ● 3.5 ● ● pseudobulge (n b <2) ● ● ● ● ● ● ● classical bulge (n b >2) ● ● ● ● – long-slit observations in Fall83 ● ● ● ● ● 3D fit ● ● ● ● ● ● ● ● ● ● 2D fit ● ● ● ● ● ● ● ● ● ● ● – data to 1 effective radius in ● ● ● ● ● ● ● log(j ∗ [kpc km s − 1 ]) ● ● 3.0 ● ● ● ● Cortese+16 ● ● ● ● ● ● ● – extended range of morphology ● ● wrt OG14 2.5 • Agrees with CDM predictions for DM haloes. 2.0 – M * = f(M h ) as j * = f(j h ) – The M * - M h relation is β = 0 β = 0.2 β = 0.4 complex; need to test j * - j h . 1.5 8.5 9.0 9.5 10.0 10.5 11.0 11.5 log(M ∗ [M sol ])
Mass—angular momentum—bulge fraction • 3D M * – j * – B/T: alpha = 1.03 +- 0.11 4.0 THINGS • fit using R package ● RF12 ● CALIFA ● ● ● ● 3.5 ● ● pseudobulge (n b <2) ● hyper.fit ● ● ● ● ● ● classical bulge (n b >2) ● ● ● ● ● ● ● ● ● 3D fit ● ● ● ● ● ● ● ● ● ● 2D fit ● ● ● ● ● ● ● ● ● ● ● – Accounts for measurement ● ● ● ● ● ● ● log(j ∗ [kpc km s − 1 ]) ● ● 3.0 ● ● ● ● ● ● ● uncertainty in all variables ● ● ● ● ● ● as well as intrinsic scatter. 2.5 2.0 β = 0 β = 0.2 β = 0.4 1.5 8.5 9.0 9.5 10.0 10.5 11.0 11.5 log(M ∗ [M sol ]) Robotham + Obreschkow 2015
! = 1 • B/T ~ (j/M) -1 is physically-motivated via disk stability: – as j/M increases, surface density decreases – surface density ~ inverse Toomre Q – Q ~ instability against (pseudo)bulge formation – Q ~ (B/T ) -1 • empirically-supported Obreschkow + Glazebrook 2014
The pseudobulge track • Trend of increasing B/T with decreasing j/M 0.8 describes galaxies with ● THINGS RF12 ● CALIFA ● B/T <~0.4 only. all 0.6 pseudobulge(n b <2) ● classical bulge (n b >2) ● ● OG14 ● ● ● ● ● ● ● ● ● ● ● 0.4 β ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.2 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.0 − 8.0 − 7.5 − 7.0 − 6.5 log(j ∗ /M ∗ [kpc km s − 1 M sol − 1 ])
The pseudobulge track • Galaxies with B/T > 0.4 have higher j * than 0.8 predicted ● THINGS RF12 ● CALIFA ● all • Most host classical bulges 0.6 pseudobulge(n b <2) ● classical bulge (n b >2) ● ● OG14 ● ● • cf EAGLE - absence of ● ● ● ● ● ● gas-poor mergers. ● ● ● 0.4 β ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.2 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.0 − 8.0 − 7.5 − 7.0 − 6.5 log(j ∗ /M ∗ [kpc km s − 1 M sol − 1 ]) Schaye+2015, Lagos+2017
Recommend
More recommend
