Balmer Dominated Remnants: Constraints on SN Progenitors Kelly Korreck Harvard-Smithsonian Center for Astrophysics

Outline Balmer dominated remnants Science from these filaments Density, Ti/Te Neutral Modeling of the filaments Balmer Remnants as probes of the progenitor

Balmer Dominated Filaments Cygnus Loop Composite: X-ray & H- SN1006 (Raymond et al. 2007) Balmer dominated filaments outline the shock blast wave front.

Spectra of Balmer Dominated Filament Smith, Raymond, & Laming (1994) ApJ

How you get a broad and narrow H-? BROAD COMPONENT 2 steps: Downstream proton charge transfers with a neutral hydrogen to make a fast neutral hydrogen and a slow proton The fast neutral is excited by a proton or an electron Emission is Doppler shifted by the velocity of the fast neutral NARROW COMPONENT Upstream neutral excited by a proton or electron Emitted at rest wavelength

Atomic Physics behind it all Chevalier and Raymond (1978) & Chevalier, Kirshner, and Raymond (1980) proposed a method for studying neutrals based on the 2 components of the H-alpha lines.

Observations There are several ways neutrals play a role in the observations of SNR. For example, FWHM of Broad H- component depends on neutral fraction. This broad to narrow ratio, Ibroad/Inarrow indicates the sharing of heating between atomic species. The neutral fraction also effects other diagnostic lines such as HeI/HeII. Neutrals are also thought to be a possible candidate to create a pre-cursor to shock. Remnant Ibroad/I Narrow Tycho (Smith et al 1991) 1.08 SN1006 0.73 0519-69.0 0.8 0548-70.4 1.1 Neutrals don’t participate in coulomb interactions Why we care about pickup ions what are they how do we know they are there. Broad to narrow compents are still higher theoretically than what is observed, Some number of neutrals <20% can come upstream to pre-heat the shock. However, the reaction rate depends on temperature of pre-shoco material The next step is to plot ionization versus position upstream to determine where the heating can occurr and how efficient the pre-cursor is. The broad/narrow ratio decreases with increasing velocity and with neutral fraction: more neutral lower ratios.

Monte Carlo model parameters Variables Neutral fraction (1-90%) Magnetic orientation (0,45,90) Shock speed (300-3000 km/sec) Te/Tp (0.1, 0.5, 0.9) Atomic Interactions Charge transfer Excitation Ionization Low-Hybrid Wave Heating Current “stylish” wave heating Heat goes preferentially to electrons, then transfers to protons via Coulomb collisions Heating occurs if VAlfven <vgyro Can track each interaction versus distance from the shock front Input Calculations

Predicted Ibroad/Inarrow Variations based on Te/Tp= Shock Speed Magnetic Angle Smaller variations based on neutral fraction Using the Ib/In ratio from the previous results, we can predict the magnetic angle of the shock For SN 1006 ratio of 0.73 and the shock speed ~2800 km/sec, the parallel shock model fits the data as expected!

Comparison of Model to Ibroad/Inarrow Observed in Supernova Remnant Code Result Obs. Ratio Tycho (Smith et al 1991) 1.04-2.4 1.08 SN1006 0.47-1.1 0.73 0519-69.0 1.0-1.4 0.8 0548-70.4 1.1 Past work examined equilibrium according to shock soeed

Precursor heating Depends on Shock speed Neutral fraction 60K increase versus the MK temperatures – no effect on the pre-shock area Precursor extends to only one mean free path behind the shock

Recent Neutral Model Heng and Mc Cray(ApJ 2007) SNR 1987A reverse shock reveals inconsistencies in the broad to narrow component ration in current models. --Velocity needs to increase to account for the greater likelihood of interaction with a proton that has a relative speed not as great as 3/4 vshock

Neutral conclusions Neutral interactions are not a strong precursor to the shock The broad to narrow intensity ratio is highly dependant on velocity and temperature equilibration (or lack thereof) Neutral fraction has a decreased effect as the shock velocity increases-could be explained by the fall off of the charge exchange cross section with increasing shock speed as seen in Heng & McCray (2007, ApJ) Transition region of the filament is important to get the proper velocity and broad to narrow ratio.

Balmer Filaments as Structure Probes

ISM interaction/structure Temperatures and densities Infer the structure of the ISM Magnetic field information from shock physics Waves/Instabilities- RT, KH, RM ….

SN1006-Balmer Filament (Raymond et al. ApJ 2007) Northwest region of the filament From past observations: Thermal x-ray emission (Long et al. 2003, ApJ, 586, 1162) Low density ISM ~0.25 cm-3 Ejecta knots are present nearby the HST observation- these knots have been observed in X-rays (Chandra)

Structure of the Balmer Filament Length scale of the ripples are about 1/10 of the radius of curvature Ripples length scales can be accounted for with general ISM turbulence (~20% density fluctuations on a parsec scale) The amplitude of the ripples however are stronger than the expected Kolmogorov spectra.

Balmer Filaments and Progenitors

SNR Balmer filament clues to SNe Balmer width and structure--Structure of the ISM/CSM surrounding the explosion Temperature , density of ISM---how much energy is deposited pre-explosion

Can we really “see” the CMS? When does the CSM lose the signature of the progenitor: Take a single degenerate case - WD + MS (following Wood-Vasey and Sokoloski, 2006) •Assume a wind that creates a cavity with a r~1.5 x1015 cm •This will “relax”, meaning that the wind will equilibrate to the mean ISM value in t=4 x 105 years So if the SN explosion goes off within ~40,000 years of the end of accretion there is a chance to “see” signatures of the CSM from the remnant interaction in the form of a Balmer filament. Similar work was done for SSXS by Chiang and Rappaport (1996).

Cloudy simulations Photoionization code used to simulate the turn on and off of the progenitor’s photoinoizing radiation pre-explosion Examined Luminosity of 1038 ergs Looked at the ionization at 100, 1 000, 10 000, 100 000 years after the source has shut off For now: a cavity structure with an initial radius of 10^16 cm, density of 10 cm^-3 Take a snapshot of the neutral fraction at a distance of ~10^17 cm as that is an approximation based on where Balmer filaments are found in SN1006

Answers given by cloudy There is a rather significant amount of ionization after 100,000 years! H+/H0~0.2= 80% neutral for 100,000 years at 10^17 cm from the central photoionizing source Much more work to be done- Such as simple case of constant density

Conclusions on Balmer remnants Great place to explore ISM/Blast wave interactions Can get information about Te, Tp, Tion, neutral fraction Still need more work with modeling the progenitor effect on ISM to see what types of limits can be put onto Type 1a Progenitors

Future Campaign issues to resolve with Balmer remnants Transition zone characterization with deep optical observations Progenitor signatures from Balmer filaments and other shock physics of the SNR Why the narrow line isn’t as narrow as it could be?