Hidden diversity of intermediate redshift galaxies

Katarzyna Małek*, Agnieszka Pollo, Małgorzata Siudek
 

National Centre for Nuclear Research, Poland

Laboratoire d’Astrophysique de Marseille, France

From galaxies to cosmology with large spectroscopic surveys, Marseille, 4-8 July 2022

Outline

• too short overview of the VIPERS project, 
• classification if z~1 (and 0),
• sub-classes vs environment - a hint for different evolutionary paths.

K.Małek, Marseille, 4-8 July 2022

K.Małek, Marseille, 4-8 July 2022

the intermediate redshift equivalent of state-of-the-art local surveys 

completed Large ESO Programme, (2008-2016, PI: L. Guzzo)

• designed to investigate the spatial distribution of galaxies at  z~1 (i<22.5, z>0.5 colour--colour pre-selection),
• built of W1 and 4 CFHTLS-Wide fields (23.5 \(deg\raisebox{0.25em}{2}\)),
• spec-z for nearly 90 000 (!) galaxies.  

based on VVDS data:

z>0.5,  z<0.5

Scodeggio et al. 2016,  PDR-2

K.Małek, Marseille, 4-8 July 2022

Guzzo et al. 2013, Garilli et al. 2014, Scodeggio et al. 2018

the intermediate redshift equivalent of state-of-the-art local surveys 

K.Małek, Marseille, 4-8 July 2022

the intermediate redshift equivalent of state-of-the-art local surveys 

We are able to trace the the evolution from the structures observed at z~0.7 to the well-known sequence in the local Universe.

K.Małek, Marseille, 4-8 July 2022

the intermediate redshift equivalent of state-of-the-art local surveys 

​The spectra were collected by VIMOS spectrograph

(LR Red grism, \(\lambda\):  5,500-9,500\(\mathring{A}\), R~220).

Sccodeggio et al. 2016

Classification if z~1

K.Małek, Marseille, 4-8 July 2022

classification if z~1,

supervised

galaxies, AGNs, stars

KM et al. 2013

K.Małek, Marseille, 4-8 July 2022

KM+2013 - Support Vector Machine (SVM), a supervised classifier applied for AGN/star/galaxy selection  based on available photometry (ugriz+ )

galaxies, AGNs, stars

KM et al. 2013

ugri

ugri+NIR

classification if z~1,

supervised

K.Małek, Marseille, 4-8 July 2022

classification if z~1,

Is the galaxy/star/AGN selection enough to trace evolutionary paths?   

K.Małek, Marseille, 4-8 July 2022

classification if z~1,

Is the galaxy/star/AGN selection enough to trace evolutionary paths?   

K.Małek, Marseille, 4-8 July 2022

classification if z~1,

Is the galaxy/star/AGN selection enough to trace evolutionary paths?   

Can we divide z~1 galaxies into smaller subsamples (smaller than red/blue/green)? 

K.Małek, Marseille, 4-8 July 2022

classification if z~1,

Is the galaxy/star/AGN selection enough to trace evolutionary paths?   

Can we divide z~1 galaxies into smaller subsamples (smaller than red/blue/green)? 

K.Małek, Marseille, 4-8 July 2022

classification if z~1, unsupervised Fisher Expectation-Maximisation method

Unsupervised Fisher Expectation-Maximisation classification of VIPERS galaxies using a 13D feature space (rest-frame UV-optical-NIR colours, no direct spectroscopic information  zspec for absolute magnitudes).

Bouveyron & Brunet 2011

Bouveyron et al. 2012

K.Małek, Marseille, 4-8 July 2022

How many galaxy populations can be blindly selected at z~1?

classification if z~1, unsupervised Fisher Expectation-Maximisation method

Siudek,KM,Pollo et al. 2013

K.Małek, Marseille, 4-8 July 2022

classification if z~1, unsupervised Fisher Expectation-Maximisation method

Siudek,KM,Pollo et al. 2018, but also Turner et al. 2021 for z~0

11 subclasses well separated in
a multidimensional photometric space.

Davidzon et al. 2013

K.Małek, Marseille, 4-8 July 2022

classification if z~1, unsupervised Fisher Expectation-Maximisation method

Siudek,KM,Pollo et al. 2018

Eleven subclasses well separated in a multiD

PHOTOMETRIC and SPECTROSCOPIC space

Subclasses of red/green/blue galaxies vs environment

K.Małek, Marseille, 4-8 July 2022

Does the environment matter?

~32k galaxies involved in this study

Siudek,KM,Pollo et al. 2022

δ (local density contrast)

Cucciati et al. 2017):

• Volume-limited tracers MB < 20.4 − z,
• cylinders (±1000km/s) and the radius (5th NN),
• scales between 2 and 6 Mpc/h.

K.Małek, Marseille, 4-8 July 2022

Are all red subclasses similar?

C1: compact

independently or mass driven

C2&C3

mass+enviroment-driven 

the same preference for denser environments, but:

• their sizes differ and correlate with the local environment in different ways:

  • C3 suggests dry merger activity,

  • C1 quenched mostly as a result of internal processes.

K.Małek, Marseille, 4-8 July 2022

Are all red subclasses similar? NOT

More about galaxies from C1/C2 classes you can find during Krzysztof Lisiecki talk (red nuggets at the intermediate z)

K.Małek, Marseille, 4-8 July 2022

Are the green subclasses similar boring?

only ~600 galaxies

K.Małek, Marseille, 4-8 July 2022

C4-C6:

low mass green galaxies behave like passive galaxies; high mass ones - are like active galaxies

High-mass (log(Mstar/M)>10.6) green galaxies:

the positive fraction-density relation suggesting that environmental quenching is more important in the evolution of high-mass green galaxies.

passive-like

Are the green subclasses similar boring? NOT

K.Małek, Marseille, 4-8 July 2022

C10:

the smallest & the least massive follows the downsizing trend  (slow accretion of surrounding gas) 

The downsizing is driven mainly by class of the smallest and the least-massive galaxies (C10). The other blue subclasses may be a subject of a mixture of mass- & environment-driven evolution.

Are all blue cloud galaxies

similar? 

~9200 galaxies

K.Małek, Marseille, 4-8 July 2022

C10:

the smallest & the least massive follows the downsizing trend  (slow accretion of surrounding gas) 

The downsizing is driven mainly by class of the smallest and the least-massive galaxies (C10). The other blue subclasses may be a subject of a mixture of mass- & environment-driven evolution.

Are all blue cloud galaxies

similar? Difficult to say ..

~9200 galaxies

K.Małek, Marseille, 4-8 July 2022

Does the environment matter? YES

Siudek,KM,Pollo et al. 2022

Detailed FEM classification allows for deeper insight into the evolution-environment relations and environmental paths.

• Red compact galaxies are formed in-situ. Red large galaxies  experienced merger processes,

• Strong dependence of green galaxies on the transition mass (for z~0.7 log(Mstar/M) = 10.6),

• The downsizing trend for blue galaxies is driven mostly by one blue subclass gathering the smallest and the least massive galaxies.

Yes, the enviroment matters !

Thank you for your attention

main properties of the FEM classes

Davidzon et al. 2013

K.Małek, Marseille, 4-8 July 2022

the intermediate redshift equivalent of state-of-the-art local surveys 

​The spectra were collected by VIMOS spectrograph

(LR Red grism, \(\lambda\):  5,500-9,500\(\mathring{A}\), R~220).

Sccodeggio et al. 2016