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 seethem out to Gpc distances
High-redshift SN
SN Light Curves - Type Ia
Note: this doesn’twork in the “R” or “I”bands (which iswhat you want touse for dusty hostgalaxies)
The brightest SNe(intrinsically) have alonger rise anddecline time; thefaintest have ashorter rise anddecline time
Type Ia Light Curves in Different Bandpasses
Peak in brightnessoccurs at differenttimes in differentbandpasses, and insome cases there is asecondary peak (i.e.,wavelengths longerthan R band)
Vertical axis: number of magnitudes by which the SNhas declined in B-band over the first 15 days aftermaximum brightness
Horizontal axis: mean I-band flux (relative tomaximum) over the 20 to 40 days after the max.brightness in B-band occurred
Vertical axis: I-band flux of the supernova (relative tomaximum I-band flux)
Horizontal axis: time since the maximum in B-bandoccurred (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 toexpand more quickly than would otherwise expect (i.e., it should make theuniverse’s “brakes” weaker or even non-existent)
•Faster than expected expansion = bigger distances to cosmological objects thanexpected = standard candles (i.e., Type I-a SNe) should seem “fainter” than theyotherwise would be for their observed redshift
•Also should be a characteristic imprint on the temperature fluctuations of theCMBR (we’ve already seen this)
•SNe Type I-a don’t know ANYTHING about the CMBR (and vice versa), so ifboth suggest the presence of a cosmological constant, then either the universeis toying with us perversely OR we’re really on to something!
Classical Hubble Diagram for Type Ia Supernovae; at z=1.0 the difference inexpected 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 andno 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 conjunctionwith GOODS survey (ACS + NICMOS ToO follow-up); obtained 16SNe, 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 = 0.46 +/- 0.13
“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 densitycome from “total” mass-to-light ratio,assuming clusters are “fair samples” ofthe universe; can also includeconstraints on P(k) from large-scalestructure observations
Cluster constraints on dark energycome from evolution of the clustermass function with redshift (poor atthe moment due to lack of high-zclusters, but will improve!)