NGC4603

Cepheids in NGC4603

Planetary Nebula Luminosity Function Number

Milky Way novae

Planetaries vs. Cepheids

Tip of Red Giant Branch (TRGB) vs. Cepheids

SBF vs. Cepheids

SN1994d (HST Image) At peak brightness, SNe are comparable in brightness to a large spiral galaxy = you can see them out to Gpc distances

High-redshift SN

SN Light Curves - Type Ia Note: this doesn’t work in the “R” or “I” bands (which is what you want to use for dusty host galaxies) The brightest SNe (intrinsically) have a longer rise and decline time; the faintest have a shorter rise and decline time

Type Ia Light Curves in Different Bandpasses Peak in brightness occurs at different times in different bandpasses, and in some cases there is a secondary peak (i.e., wavelengths longer than R band)

Vertical axis: number of magnitudes by which the SN has declined in B-band over the first 15 days after maximum brightness Horizontal axis: mean I-band flux (relative to maximum) over the 20 to 40 days after the max. brightness in B-band occurred Vertical axis: I-band flux of the supernova (relative to maximum I-band flux) Horizontal axis: time since the maximum in B-band occurred (note the “negative time”!!) Another way to calibrate Type Ia SNe

If cosmological constant is not zero, what do you expect to see? Cosmological constant acts like “anti-gravity”; should cause the universe to expand more quickly than would otherwise expect (i.e., it should make the universe’s “brakes” weaker or even non-existent) Faster than expected expansion = bigger distances to cosmological objects than expected = standard candles (i.e., Type I-a SNe) should seem “fainter” than they otherwise would be for their observed redshift Also should be a characteristic imprint on the temperature fluctuations of the CMBR (we’ve already seen this) SNe Type I-a don’t know ANYTHING about the CMBR (and vice versa), so if both suggest the presence of a cosmological constant, then either the universe is toying with us perversely OR we’re really on to something!

Classical Hubble Diagram for Type Ia Supernovae; at z=1.0 the difference in expected magnitude for 3 wildly different cosmogonies is only about 0.5mag!! Flat, matter-dom. universe Open universe Flat, Lambda-dominated

“ Residual Hubble Diagram ” from Knop et al (2003); universe with no mass and no cosmological constant / “ dark energy ” is a flat line for all redshifts

Search for z > 1 SNe carried out by Riess et al. using HST in conjunction with GOODS survey (ACS + NICMOS ToO follow-up); obtained 16 SNe, including 6 of the 7 highest-z SNe known

Riess et al. (2004); High-z supernovae from HST show universe decelerated in the past, transition happened at z = / “ Jerk ” is a purely kinematic model; the jerk is the derivative of the deceleration parameter, and deceleration parameter is the derivative of the Hubble parameter

Cluster constraints on matter density come from “ total ” mass-to-light ratio, assuming clusters are “ fair samples ” of the universe; can also include constraints on P(k) from large-scale structure observations Cluster constraints on dark energy come from evolution of the cluster mass function with redshift (poor at the moment due to lack of high-z clusters, but will improve!)